Sync docs from master to gh-pages
This commit is contained in:
Oleg Zhurakousky
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>8. Configuration Options</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi_spring-cloud-stream-overview-binders.html" title="7. Binders"><link rel="next" href="multi_content-type-management.html" title="9. Content Type Negotiation"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">8. Configuration Options</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-binders.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi_content-type-management.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_configuration_options" href="#_configuration_options"></a>8. Configuration Options</h2></div></div></div><p>Spring Cloud Stream supports general configuration options as well as configuration for bindings and binders.
|
||||
<title>8. Configuration Options</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi_spring-cloud-stream-overview-binders.html" title="7. Binders"><link rel="next" href="multi_content-type-management.html" title="9. Content Type Negotiation"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">8. Configuration Options</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-binders.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi_content-type-management.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_configuration_options" href="#_configuration_options"></a>8. Configuration Options</h2></div></div></div><p>Spring Cloud Stream supports general configuration options as well as configuration for bindings and binders.
|
||||
Some binders let additional binding properties support middleware-specific features.</p><p>Configuration options can be provided to Spring Cloud Stream applications through any mechanism supported by Spring Boot.
|
||||
This includes application arguments, environment variables, and YAML or .properties files.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_binding_service_properties" href="#_binding_service_properties"></a>8.1 Binding Service Properties</h2></div></div></div><p>These properties are exposed via <code class="literal">org.springframework.cloud.stream.config.BindingServiceProperties</code></p><div class="variablelist"><dl class="variablelist"><dt><span class="term">spring.cloud.stream.instanceCount</span></dt><dd><p class="simpara">The number of deployed instances of an application.
|
||||
Must be set for partitioning on the producer side. Must be set on the consumer side when using RabbitMQ and with Kafka if <code class="literal">autoRebalanceEnabled=false</code>.</p><p class="simpara">Default: <code class="literal">1</code>.</p></dd><dt><span class="term">spring.cloud.stream.instanceIndex</span></dt><dd>The instance index of the application: A number from <code class="literal">0</code> to <code class="literal">instanceCount - 1</code>.
|
||||
@@ -124,4 +124,4 @@ It has one method:</p><pre class="programlisting"><span xmlns:d="http://docbook.
|
||||
extended.setAutoBindDlq(true);
|
||||
extended.setDeadLetterQueueName(<span xmlns:d="http://docbook.org/ns/docbook" class="hl-string">"myDLQ"</span>);
|
||||
};
|
||||
}</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>If you need to support dynamic destinations with multiple binder types, use <code class="literal">Object</code> for the generic type and cast the <code class="literal">extended</code> argument as needed.</p></td></tr></table></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-binders.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_content-type-management.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">7. Binders </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 9. Content Type Negotiation</td></tr></table></div></body></html>
|
||||
}</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>If you need to support dynamic destinations with multiple binder types, use <code class="literal">Object</code> for the generic type and cast the <code class="literal">extended</code> argument as needed.</p></td></tr></table></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-binders.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_content-type-management.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">7. Binders </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 9. Content Type Negotiation</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>13. Health Indicator</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi__testing.html" title="12. Testing"><link rel="next" href="multi_spring-cloud-stream-overview-metrics-emitter.html" title="14. Metrics Emitter"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">13. Health Indicator</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__testing.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_health_indicator" href="#_health_indicator"></a>13. Health Indicator</h2></div></div></div><p>Spring Cloud Stream provides a health indicator for binders.
|
||||
<title>13. Health Indicator</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__testing.html" title="12. Testing"><link rel="next" href="multi_spring-cloud-stream-overview-metrics-emitter.html" title="14. Metrics Emitter"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">13. Health Indicator</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__testing.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_health_indicator" href="#_health_indicator"></a>13. Health Indicator</h2></div></div></div><p>Spring Cloud Stream provides a health indicator for binders.
|
||||
It is registered under the name <code class="literal">binders</code> and can be enabled or disabled by setting the <code class="literal">management.health.binders.enabled</code> property.</p><p>To enable health check you first need to enable both "web" and "actuator" by including its dependencies (see <a class="xref" href="multi__whats_new_in_2_0.html#spring-cloud-stream-preface-actuator-web-dependencies" title="3.2.1 Both Actuator and Web Dependencies Are Now Optional">Section 3.2.1, “Both Actuator and Web Dependencies Are Now Optional”</a>)</p><p>If <code class="literal">management.health.binders.enabled</code> is not set explicitly by the application, then <code class="literal">management.health.defaults.enabled</code> is matched as <code class="literal">true</code> and the binder health indicators are enabled.
|
||||
If you want to disable health indicator completely, then you have to set <code class="literal">management.health.binders.enabled</code> to <code class="literal">false</code>.</p><p>You can use Spring Boot actuator health endpoint to access the health indicator - <code class="literal">/actuator/health</code>.
|
||||
By default, you will only receive the top level application status when you hit the above endpoint.
|
||||
@@ -9,4 +9,4 @@ you can do so by setting property <code class="literal">management.health.binder
|
||||
In this case, the health indicator infrastructure from Spring Boot will still pick up these custom beans.
|
||||
Even if you are not disabling the binder health indicators, you can still enhance the health checks by providing your own <code class="literal">HealthIndicator</code> beans in addition to the out of the box health checks.</p><p>When you have multiple binders in the same application, health indicators are enabled by default unless the application turns them off by setting <code class="literal">management.health.binders.enabled</code> to <code class="literal">false</code>.
|
||||
In this case, if the user wants to disable health check for a subset of the binders, then that should be done by setting <code class="literal">management.health.binders.enabled</code> to <code class="literal">false</code> in the multi binder configurations’s environment.
|
||||
See <a class="link" href="multi_spring-cloud-stream-overview-binders.html#multiple-systems" title="7.5 Connecting to Multiple Systems">Connecting to Multiple Systems</a> for details on how environment specific properties can be provided.</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__testing.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">12. Testing </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 14. Metrics Emitter</td></tr></table></div></body></html>
|
||||
See <a class="link" href="multi_spring-cloud-stream-overview-binders.html#multiple-systems" title="7.5 Connecting to Multiple Systems">Connecting to Multiple Systems</a> for details on how environment specific properties can be provided.</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__testing.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">12. Testing </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 14. Metrics Emitter</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>11. Inter-Application Communication</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi_schema-evolution.html" title="10. Schema Evolution Support"><link rel="next" href="multi__testing.html" title="12. Testing"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">11. Inter-Application Communication</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_schema-evolution.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__testing.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_inter_application_communication" href="#_inter_application_communication"></a>11. Inter-Application Communication</h2></div></div></div><p>Spring Cloud Stream enables communication between applications. Inter-application communication is a complex issue spanning several concerns, as described in the following topics:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi__inter_application_communication.html#spring-cloud-stream-overview-connecting-multiple-application-instances" title="11.1 Connecting Multiple Application Instances">Section 11.1, “Connecting Multiple Application Instances”</a></span>”</span></li><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi__inter_application_communication.html#spring-cloud-stream-overview-instance-index-instance-count" title="11.2 Instance Index and Instance Count">Section 11.2, “Instance Index and Instance Count”</a></span>”</span></li><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi__inter_application_communication.html#spring-cloud-stream-overview-partitioning" title="11.3 Partitioning">Section 11.3, “Partitioning”</a></span>”</span></li></ul></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-overview-connecting-multiple-application-instances" href="#spring-cloud-stream-overview-connecting-multiple-application-instances"></a>11.1 Connecting Multiple Application Instances</h2></div></div></div><p>While Spring Cloud Stream makes it easy for individual Spring Boot applications to connect to messaging systems, the typical scenario for Spring Cloud Stream is the creation of multi-application pipelines, where microservice applications send data to each other.
|
||||
<title>11. Inter-Application Communication</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi_schema-evolution.html" title="10. Schema Evolution Support"><link rel="next" href="multi__testing.html" title="12. Testing"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">11. Inter-Application Communication</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_schema-evolution.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__testing.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_inter_application_communication" href="#_inter_application_communication"></a>11. Inter-Application Communication</h2></div></div></div><p>Spring Cloud Stream enables communication between applications. Inter-application communication is a complex issue spanning several concerns, as described in the following topics:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi__inter_application_communication.html#spring-cloud-stream-overview-connecting-multiple-application-instances" title="11.1 Connecting Multiple Application Instances">Section 11.1, “Connecting Multiple Application Instances”</a></span>”</span></li><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi__inter_application_communication.html#spring-cloud-stream-overview-instance-index-instance-count" title="11.2 Instance Index and Instance Count">Section 11.2, “Instance Index and Instance Count”</a></span>”</span></li><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi__inter_application_communication.html#spring-cloud-stream-overview-partitioning" title="11.3 Partitioning">Section 11.3, “Partitioning”</a></span>”</span></li></ul></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-overview-connecting-multiple-application-instances" href="#spring-cloud-stream-overview-connecting-multiple-application-instances"></a>11.1 Connecting Multiple Application Instances</h2></div></div></div><p>While Spring Cloud Stream makes it easy for individual Spring Boot applications to connect to messaging systems, the typical scenario for Spring Cloud Stream is the creation of multi-application pipelines, where microservice applications send data to each other.
|
||||
You can achieve this scenario by correlating the input and output destinations of <span class="quote">“<span class="quote">adjacent</span>”</span> applications.</p><p>Suppose a design calls for the Time Source application to send data to the Log Sink application. You could use a common destination named <code class="literal">ticktock</code> for bindings within both applications.</p><p>Time Source (that has the channel name <code class="literal">output</code>) would set the following property:</p><pre class="screen">spring.cloud.stream.bindings.output.destination=ticktock</pre><p>Log Sink (that has the channel name <code class="literal">input</code>) would set the following property:</p><pre class="screen">spring.cloud.stream.bindings.input.destination=ticktock</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-overview-instance-index-instance-count" href="#spring-cloud-stream-overview-instance-index-instance-count"></a>11.2 Instance Index and Instance Count</h2></div></div></div><p>When scaling up Spring Cloud Stream applications, each instance can receive information about how many other instances of the same application exist and what its own instance index is.
|
||||
Spring Cloud Stream does this through the <code class="literal">spring.cloud.stream.instanceCount</code> and <code class="literal">spring.cloud.stream.instanceIndex</code> properties.
|
||||
For example, if there are three instances of a HDFS sink application, all three instances have <code class="literal">spring.cloud.stream.instanceCount</code> set to <code class="literal">3</code>, and the individual applications have <code class="literal">spring.cloud.stream.instanceIndex</code> set to <code class="literal">0</code>, <code class="literal">1</code>, and <code class="literal">2</code>, respectively.</p><p>When Spring Cloud Stream applications are deployed through Spring Cloud Data Flow, these properties are configured automatically; when Spring Cloud Stream applications are launched independently, these properties must be set correctly.
|
||||
@@ -34,4 +34,4 @@ With Kafka, if <code class="literal">autoRebalanceEnabled</code> is <code class=
|
||||
If <code class="literal">autoRebalanceEnabled</code> is set to false, the <code class="literal">instanceCount</code> and <code class="literal">instanceIndex</code> are used by the binder to determine which partition(s) the instance subscribes to (you must have at least as many partitions as there are instances).
|
||||
The binder allocates the partitions instead of Kafka.
|
||||
This might be useful if you want messages for a particular partition to always go to the same instance.
|
||||
When a binder configuration requires them, it is important to set both values correctly in order to ensure that all of the data is consumed and that the application instances receive mutually exclusive datasets.</p><p>While a scenario in which using multiple instances for partitioned data processing may be complex to set up in a standalone case, Spring Cloud Dataflow can simplify the process significantly by populating both the input and output values correctly and by letting you rely on the runtime infrastructure to provide information about the instance index and instance count.</p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_schema-evolution.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__testing.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">10. Schema Evolution Support </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 12. Testing</td></tr></table></div></body></html>
|
||||
When a binder configuration requires them, it is important to set both values correctly in order to ensure that all of the data is consumed and that the application instances receive mutually exclusive datasets.</p><p>While a scenario in which using multiple instances for partitioned data processing may be complex to set up in a standalone case, Spring Cloud Dataflow can simplify the process significantly by populating both the input and output values correctly and by letting you rely on the runtime infrastructure to provide information about the instance index and instance count.</p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_schema-evolution.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__testing.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">10. Schema Evolution Support </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 12. Testing</td></tr></table></div></body></html>
|
||||
@@ -1,9 +1,9 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>5. Main Concepts</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi_spring-cloud-stream-overview-introducing.html" title="4. Introducing Spring Cloud Stream"><link rel="next" href="multi__programming_model.html" title="6. Programming Model"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5. Main Concepts</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-introducing.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__programming_model.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_main_concepts" href="#_main_concepts"></a>5. Main Concepts</h2></div></div></div><p>Spring Cloud Stream provides a number of abstractions and primitives that simplify the writing of message-driven microservice applications.
|
||||
<title>5. Main Concepts</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi_spring-cloud-stream-overview-introducing.html" title="4. Introducing Spring Cloud Stream"><link rel="next" href="multi__programming_model.html" title="6. Programming Model"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5. Main Concepts</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-introducing.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__programming_model.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_main_concepts" href="#_main_concepts"></a>5. Main Concepts</h2></div></div></div><p>Spring Cloud Stream provides a number of abstractions and primitives that simplify the writing of message-driven microservice applications.
|
||||
This section gives an overview of the following:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="multi__main_concepts.html#spring-cloud-stream-overview-application-model" title="5.1 Application Model">Spring Cloud Stream’s application model</a></li><li class="listitem"><a class="xref" href="multi__main_concepts.html#spring-cloud-stream-overview-binder-abstraction" title="5.2 The Binder Abstraction">Section 5.2, “The Binder Abstraction”</a></li><li class="listitem"><a class="link" href="multi__main_concepts.html#spring-cloud-stream-overview-persistent-publish-subscribe-support" title="5.3 Persistent Publish-Subscribe Support">Persistent publish-subscribe support</a></li><li class="listitem"><a class="link" href="multi__main_concepts.html#consumer-groups" title="5.4 Consumer Groups">Consumer group support</a></li><li class="listitem"><a class="link" href="multi__main_concepts.html#partitioning" title="5.6 Partitioning Support">Partitioning support</a></li><li class="listitem"><a class="link" href="multi_spring-cloud-stream-overview-binders.html#spring-cloud-stream-overview-binder-api" title="7.2 Binder SPI">A pluggable Binder SPI</a></li></ul></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-overview-application-model" href="#spring-cloud-stream-overview-application-model"></a>5.1 Application Model</h2></div></div></div><p>A Spring Cloud Stream application consists of a middleware-neutral core.
|
||||
The application communicates with the outside world through input and output channels injected into it by Spring Cloud Stream.
|
||||
Channels are connected to external brokers through middleware-specific Binder implementations.</p><div class="figure"><a name="d0e737" href="#d0e737"></a><p class="title"><b>Figure 5.1. Spring Cloud Stream Application</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-with-binder.png" align="middle" alt="SCSt with binder"></div></div></div><br class="figure-break"><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_fat_jar" href="#_fat_jar"></a>5.1.1 Fat JAR</h3></div></div></div><p>Spring Cloud Stream applications can be run in stand-alone mode from your IDE for testing.
|
||||
Channels are connected to external brokers through middleware-specific Binder implementations.</p><div class="figure"><a name="d0e728" href="#d0e728"></a><p class="title"><b>Figure 5.1. Spring Cloud Stream Application</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-with-binder.png" align="middle" alt="SCSt with binder"></div></div></div><br class="figure-break"><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_fat_jar" href="#_fat_jar"></a>5.1.1 Fat JAR</h3></div></div></div><p>Spring Cloud Stream applications can be run in stand-alone mode from your IDE for testing.
|
||||
To run a Spring Cloud Stream application in production, you can create an executable (or <span class="quote">“<span class="quote">fat</span>”</span>) JAR by using the standard Spring Boot tooling provided for Maven or Gradle. See the <a class="link" href="https://docs.spring.io/spring-boot/docs/current/reference/html/howto-build.html#howto-create-an-executable-jar-with-maven" target="_top">Spring Boot Reference Guide</a> for more details.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-overview-binder-abstraction" href="#spring-cloud-stream-overview-binder-abstraction"></a>5.2 The Binder Abstraction</h2></div></div></div><p>Spring Cloud Stream provides Binder implementations for <a class="link" href="https://github.com/spring-cloud/spring-cloud-stream-binder-kafka" target="_top">Kafka</a> and <a class="link" href="https://github.com/spring-cloud/spring-cloud-stream-binder-rabbit" target="_top">Rabbit MQ</a>.
|
||||
Spring Cloud Stream also includes a <a class="link" href="https://github.com/spring-cloud/spring-cloud-stream/blob/master/spring-cloud-stream-test-support/src/main/java/org/springframework/cloud/stream/test/binder/TestSupportBinder.java" target="_top">TestSupportBinder</a>, which leaves a channel unmodified so that tests can interact with channels directly and reliably assert on what is received.
|
||||
You can also use the extensible API to write your own Binder.</p><p>Spring Cloud Stream uses Spring Boot for configuration, and the Binder abstraction makes it possible for a Spring Cloud Stream application to be flexible in how it connects to middleware.
|
||||
@@ -13,7 +13,7 @@ In the sink example from the <a class="xref" href="multi_spring-cloud-stream-ove
|
||||
You can use different types of middleware with the same code.
|
||||
To do so, include a different binder at build time.
|
||||
For more complex use cases, you can also package multiple binders with your application and have it choose the binder( and even whether to use different binders for different channels) at runtime.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-overview-persistent-publish-subscribe-support" href="#spring-cloud-stream-overview-persistent-publish-subscribe-support"></a>5.3 Persistent Publish-Subscribe Support</h2></div></div></div><p>Communication between applications follows a publish-subscribe model, where data is broadcast through shared topics.
|
||||
This can be seen in the following figure, which shows a typical deployment for a set of interacting Spring Cloud Stream applications.</p><div class="figure"><a name="d0e800" href="#d0e800"></a><p class="title"><b>Figure 5.2. Spring Cloud Stream Publish-Subscribe</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-sensors.png" align="middle" alt="SCSt sensors"></div></div></div><br class="figure-break"><p>Data reported by sensors to an HTTP endpoint is sent to a common destination named <code class="literal">raw-sensor-data</code>.
|
||||
This can be seen in the following figure, which shows a typical deployment for a set of interacting Spring Cloud Stream applications.</p><div class="figure"><a name="d0e791" href="#d0e791"></a><p class="title"><b>Figure 5.2. Spring Cloud Stream Publish-Subscribe</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-sensors.png" align="middle" alt="SCSt sensors"></div></div></div><br class="figure-break"><p>Data reported by sensors to an HTTP endpoint is sent to a common destination named <code class="literal">raw-sensor-data</code>.
|
||||
From the destination, it is independently processed by a microservice application that computes time-windowed averages and by another microservice application that ingests the raw data into HDFS (Hadoop Distributed File System).
|
||||
In order to process the data, both applications declare the topic as their input at runtime.</p><p>The publish-subscribe communication model reduces the complexity of both the producer and the consumer and lets new applications be added to the topology without disruption of the existing flow.
|
||||
For example, downstream from the average-calculating application, you can add an application that calculates the highest temperature values for display and monitoring.
|
||||
@@ -23,7 +23,7 @@ By using native middleware support, Spring Cloud Stream also simplifies use of t
|
||||
When doing so, different instances of an application are placed in a competing consumer relationship, where only one of the instances is expected to handle a given message.</p><p>Spring Cloud Stream models this behavior through the concept of a consumer group.
|
||||
(Spring Cloud Stream consumer groups are similar to and inspired by Kafka consumer groups.)
|
||||
Each consumer binding can use the <code class="literal">spring.cloud.stream.bindings.<channelName>.group</code> property to specify a group name.
|
||||
For the consumers shown in the following figure, this property would be set as <code class="literal">spring.cloud.stream.bindings.<channelName>.group=hdfsWrite</code> or <code class="literal">spring.cloud.stream.bindings.<channelName>.group=average</code>.</p><div class="figure"><a name="d0e834" href="#d0e834"></a><p class="title"><b>Figure 5.3. Spring Cloud Stream Consumer Groups</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-groups.png" align="middle" alt="SCSt groups"></div></div></div><br class="figure-break"><p>All groups that subscribe to a given destination receive a copy of published data, but only one member of each group receives a given message from that destination.
|
||||
For the consumers shown in the following figure, this property would be set as <code class="literal">spring.cloud.stream.bindings.<channelName>.group=hdfsWrite</code> or <code class="literal">spring.cloud.stream.bindings.<channelName>.group=average</code>.</p><div class="figure"><a name="d0e825" href="#d0e825"></a><p class="title"><b>Figure 5.3. Spring Cloud Stream Consumer Groups</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-groups.png" align="middle" alt="SCSt groups"></div></div></div><br class="figure-break"><p>All groups that subscribe to a given destination receive a copy of published data, but only one member of each group receives a given message from that destination.
|
||||
By default, when a group is not specified, Spring Cloud Stream assigns the application to an anonymous and independent single-member consumer group that is in a publish-subscribe relationship with all other consumer groups.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="consumer-types" href="#consumer-types"></a>5.5 Consumer Types</h2></div></div></div><p>Two types of consumer are supported:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Message-driven (sometimes referred to as Asynchronous)</li><li class="listitem">Polled (sometimes referred to as Synchronous)</li></ul></div><p>Prior to version 2.0, only asynchronous consumers were supported. A message is delivered as soon as it is available and a thread is available to process it.</p><p>When you wish to control the rate at which messages are processed, you might want to use a synchronous consumer.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="durability" href="#durability"></a>5.5.1 Durability</h3></div></div></div><p>Consistent with the opinionated application model of Spring Cloud Stream, consumer group subscriptions are durable.
|
||||
That is, a binder implementation ensures that group subscriptions are persistent and that, once at least one subscription for a group has been created, the group receives messages, even if they are sent while all applications in the group are stopped.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>Anonymous subscriptions are non-durable by nature.
|
||||
For some binder implementations (such as RabbitMQ), it is possible to have non-durable group subscriptions.</p></td></tr></table></div><p>In general, it is preferable to always specify a consumer group when binding an application to a given destination.
|
||||
@@ -31,5 +31,5 @@ When scaling up a Spring Cloud Stream application, you must specify a consumer g
|
||||
Doing so prevents the application’s instances from receiving duplicate messages (unless that behavior is desired, which is unusual).</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="partitioning" href="#partitioning"></a>5.6 Partitioning Support</h2></div></div></div><p>Spring Cloud Stream provides support for partitioning data between multiple instances of a given application.
|
||||
In a partitioned scenario, the physical communication medium (such as the broker topic) is viewed as being structured into multiple partitions.
|
||||
One or more producer application instances send data to multiple consumer application instances and ensure that data identified by common characteristics are processed by the same consumer instance.</p><p>Spring Cloud Stream provides a common abstraction for implementing partitioned processing use cases in a uniform fashion.
|
||||
Partitioning can thus be used whether the broker itself is naturally partitioned (for example, Kafka) or not (for example, RabbitMQ).</p><div class="figure"><a name="d0e878" href="#d0e878"></a><p class="title"><b>Figure 5.4. Spring Cloud Stream Partitioning</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-partitioning.png" align="middle" alt="SCSt partitioning"></div></div></div><br class="figure-break"><p>Partitioning is a critical concept in stateful processing, where it is critical (for either performance or consistency reasons) to ensure that all related data is processed together.
|
||||
For example, in the time-windowed average calculation example, it is important that all measurements from any given sensor are processed by the same application instance.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>To set up a partitioned processing scenario, you must configure both the data-producing and the data-consuming ends.</p></td></tr></table></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-introducing.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__programming_model.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">4. Introducing Spring Cloud Stream </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 6. Programming Model</td></tr></table></div></body></html>
|
||||
Partitioning can thus be used whether the broker itself is naturally partitioned (for example, Kafka) or not (for example, RabbitMQ).</p><div class="figure"><a name="d0e869" href="#d0e869"></a><p class="title"><b>Figure 5.4. Spring Cloud Stream Partitioning</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-partitioning.png" align="middle" alt="SCSt partitioning"></div></div></div><br class="figure-break"><p>Partitioning is a critical concept in stateful processing, where it is critical (for either performance or consistency reasons) to ensure that all related data is processed together.
|
||||
For example, in the time-windowed average calculation example, it is important that all measurements from any given sensor are processed by the same application instance.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>To set up a partitioned processing scenario, you must configure both the data-producing and the data-consuming ends.</p></td></tr></table></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-introducing.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__programming_model.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">4. Introducing Spring Cloud Stream </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 6. Programming Model</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>6. Programming Model</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi__main_concepts.html" title="5. Main Concepts"><link rel="next" href="multi_spring-cloud-stream-overview-binders.html" title="7. Binders"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">6. Programming Model</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__main_concepts.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-binders.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_programming_model" href="#_programming_model"></a>6. Programming Model</h2></div></div></div><p>To understand the programming model, you should be familiar with the following core concepts:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>Destination Binders:</strong></span> Components responsible to provide integration with the external messaging systems.</li><li class="listitem"><span class="strong"><strong>Destination Bindings:</strong></span> Bridge between the external messaging systems and application provided <span class="emphasis"><em>Producers</em></span> and <span class="emphasis"><em>Consumers</em></span> of messages (created by the Destination Binders).</li><li class="listitem"><span class="strong"><strong>Message:</strong></span> The canonical data structure used by producers and consumers to communicate with Destination Binders (and thus other applications via external messaging systems).</li></ul></div><div class="informalfigure"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-overview.png" align="middle" alt="SCSt overview"></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_destination_binders" href="#_destination_binders"></a>6.1 Destination Binders</h2></div></div></div><p>Destination Binders are extension components of Spring Cloud Stream responsible for providing the necessary configuration and implementation to facilitate
|
||||
<title>6. Programming Model</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__main_concepts.html" title="5. Main Concepts"><link rel="next" href="multi_spring-cloud-stream-overview-binders.html" title="7. Binders"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">6. Programming Model</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__main_concepts.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-binders.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_programming_model" href="#_programming_model"></a>6. Programming Model</h2></div></div></div><p>To understand the programming model, you should be familiar with the following core concepts:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>Destination Binders:</strong></span> Components responsible to provide integration with the external messaging systems.</li><li class="listitem"><span class="strong"><strong>Destination Bindings:</strong></span> Bridge between the external messaging systems and application provided <span class="emphasis"><em>Producers</em></span> and <span class="emphasis"><em>Consumers</em></span> of messages (created by the Destination Binders).</li><li class="listitem"><span class="strong"><strong>Message:</strong></span> The canonical data structure used by producers and consumers to communicate with Destination Binders (and thus other applications via external messaging systems).</li></ul></div><div class="informalfigure"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/SCSt-overview.png" align="middle" alt="SCSt overview"></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_destination_binders" href="#_destination_binders"></a>6.1 Destination Binders</h2></div></div></div><p>Destination Binders are extension components of Spring Cloud Stream responsible for providing the necessary configuration and implementation to facilitate
|
||||
integration with external messaging systems.
|
||||
This integration is responsible for connectivity, delegation, and routing of messages to and from producers and consumers, data type conversion,
|
||||
invocation of the user code, and more.</p><p>Binders handle a lot of the boiler plate responsibilities that would otherwise fall on your shoulders. However, to accomplish that, the binder still needs
|
||||
@@ -250,7 +250,7 @@ If the service activator throws a <code class="literal">RequeueCurrentMessageExc
|
||||
The error handling comes in two flavors:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>application:</strong></span> The error handling is done within the application (custom error handler).</li><li class="listitem"><span class="strong"><strong>system:</strong></span> The error handling is delegated to the binder (re-queue, DL, and others). Note that the techniques are dependent on binder implementation and the
|
||||
capability of the underlying messaging middleware.</li></ul></div><p>Spring Cloud Stream uses the <a class="link" href="https://github.com/spring-projects/spring-retry" target="_top">Spring Retry</a> library to facilitate successful message processing. See <a class="xref" href="multi__programming_model.html#_retry_template" title="6.4.3 Retry Template">Section 6.4.3, “Retry Template”</a> for more details.
|
||||
However, when all fails, the exceptions thrown by the message handlers are propagated back to the binder. At that point, binder invokes custom error handler or communicates
|
||||
the error back to the messaging system (re-queue, DLQ, and others).</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_application_error_handling" href="#_application_error_handling"></a>6.4.1 Application Error Handling</h3></div></div></div><p>There are two types of application-level error handling. Errors can be handled at each binding subscription or a global handler can handle all the binding subscription errors. Let’s review the details.</p><div class="figure"><a name="d0e1515" href="#d0e1515"></a><p class="title"><b>Figure 6.1. A Spring Cloud Stream Sink Application with Custom and Global Error Handlers</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/custom_vs_global_error_channels.png" align="middle" alt="custom vs global error channels"></div></div></div><br class="figure-break"><p>For each input binding, Spring Cloud Stream creates a dedicated error channel with the following semantics <code class="literal"><destinationName>.errors</code>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>The <code class="literal"><destinationName></code> consists of the name of the binding (such as <code class="literal">input</code>) and the name of the group (such as <code class="literal">myGroup</code>).</p></td></tr></table></div><p>Consider the following:</p><pre class="programlisting">spring.cloud.stream.bindings.input.group=myGroup</pre><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@StreamListener(Sink.INPUT)</span></em> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-comment">// destination name 'input.myGroup'</span>
|
||||
the error back to the messaging system (re-queue, DLQ, and others).</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_application_error_handling" href="#_application_error_handling"></a>6.4.1 Application Error Handling</h3></div></div></div><p>There are two types of application-level error handling. Errors can be handled at each binding subscription or a global handler can handle all the binding subscription errors. Let’s review the details.</p><div class="figure"><a name="d0e1506" href="#d0e1506"></a><p class="title"><b>Figure 6.1. A Spring Cloud Stream Sink Application with Custom and Global Error Handlers</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/custom_vs_global_error_channels.png" align="middle" alt="custom vs global error channels"></div></div></div><br class="figure-break"><p>For each input binding, Spring Cloud Stream creates a dedicated error channel with the following semantics <code class="literal"><destinationName>.errors</code>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>The <code class="literal"><destinationName></code> consists of the name of the binding (such as <code class="literal">input</code>) and the name of the group (such as <code class="literal">myGroup</code>).</p></td></tr></table></div><p>Consider the following:</p><pre class="programlisting">spring.cloud.stream.bindings.input.group=myGroup</pre><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@StreamListener(Sink.INPUT)</span></em> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-comment">// destination name 'input.myGroup'</span>
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">void</span> handle(Person value) {
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">throw</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">new</span> RuntimeException(<span xmlns:d="http://docbook.org/ns/docbook" class="hl-string">"BOOM!"</span>);
|
||||
}
|
||||
@@ -392,4 +392,4 @@ The <code class="literal">Publisher</code> in the following example still uses R
|
||||
e -> e.poller(p -> p.fixedDelay(<span class="hl-number">1</span>)))
|
||||
.toReactivePublisher();
|
||||
}
|
||||
}</pre></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__main_concepts.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-binders.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">5. Main Concepts </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 7. Binders</td></tr></table></div></body></html>
|
||||
}</pre></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__main_concepts.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-binders.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">5. Main Concepts </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 7. Binders</td></tr></table></div></body></html>
|
||||
@@ -1,3 +1,3 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>15. Samples</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi_spring-cloud-stream-overview-metrics-emitter.html" title="14. Metrics Emitter"><link rel="next" href="multi__appendices.html" title="Part III. Appendices"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">15. Samples</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__appendices.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_samples" href="#_samples"></a>15. Samples</h2></div></div></div><p>For Spring Cloud Stream samples, see the <a class="link" href="https://github.com/spring-cloud/spring-cloud-stream-samples" target="_top">spring-cloud-stream-samples</a> repository on GitHub.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_deploying_stream_applications_on_cloudfoundry" href="#_deploying_stream_applications_on_cloudfoundry"></a>15.1 Deploying Stream Applications on CloudFoundry</h2></div></div></div><p>On CloudFoundry, services are usually exposed through a special environment variable called <a class="link" href="https://docs.cloudfoundry.org/devguide/deploy-apps/environment-variable.html#VCAP-SERVICES" target="_top">VCAP_SERVICES</a>.</p><p>When configuring your binder connections, you can use the values from an environment variable as explained on the <a class="link" href="http://docs.spring.io/spring-cloud-dataflow-server-cloudfoundry/docs/current-SNAPSHOT/reference/htmlsingle/#getting-started-ups" target="_top">dataflow Cloud Foundry Server</a> docs.</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__appendices.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">14. Metrics Emitter </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> Part III. Appendices</td></tr></table></div></body></html>
|
||||
<title>15. Samples</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi_spring-cloud-stream-overview-metrics-emitter.html" title="14. Metrics Emitter"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">15. Samples</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> </td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_samples" href="#_samples"></a>15. Samples</h2></div></div></div><p>For Spring Cloud Stream samples, see the <a class="link" href="https://github.com/spring-cloud/spring-cloud-stream-samples" target="_top">spring-cloud-stream-samples</a> repository on GitHub.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_deploying_stream_applications_on_cloudfoundry" href="#_deploying_stream_applications_on_cloudfoundry"></a>15.1 Deploying Stream Applications on CloudFoundry</h2></div></div></div><p>On CloudFoundry, services are usually exposed through a special environment variable called <a class="link" href="https://docs.cloudfoundry.org/devguide/deploy-apps/environment-variable.html#VCAP-SERVICES" target="_top">VCAP_SERVICES</a>.</p><p>When configuring your binder connections, you can use the values from an environment variable as explained on the <a class="link" href="http://docs.spring.io/spring-cloud-dataflow-server-cloudfoundry/docs/current-SNAPSHOT/reference/htmlsingle/#getting-started-ups" target="_top">dataflow Cloud Foundry Server</a> docs.</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_spring-cloud-stream-overview-metrics-emitter.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> </td></tr><tr><td width="40%" align="left" valign="top">14. Metrics Emitter </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> </td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>12. Testing</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi__inter_application_communication.html" title="11. Inter-Application Communication"><link rel="next" href="multi__health_indicator.html" title="13. Health Indicator"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">12. Testing</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__inter_application_communication.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__health_indicator.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_testing" href="#_testing"></a>12. Testing</h2></div></div></div><p>Spring Cloud Stream provides support for testing your microservice applications without connecting to a messaging system.
|
||||
<title>12. Testing</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__inter_application_communication.html" title="11. Inter-Application Communication"><link rel="next" href="multi__health_indicator.html" title="13. Health Indicator"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">12. Testing</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__inter_application_communication.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__health_indicator.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_testing" href="#_testing"></a>12. Testing</h2></div></div></div><p>Spring Cloud Stream provides support for testing your microservice applications without connecting to a messaging system.
|
||||
You can do that by using the <code class="literal">TestSupportBinder</code> provided by the <code class="literal">spring-cloud-stream-test-support</code> library, which can be added as a test dependency to the application, as shown in the following example:</p><pre class="programlisting"> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-tag"><dependency></span>
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-tag"><groupId></span>org.springframework.cloud<span xmlns:d="http://docbook.org/ns/docbook" class="hl-tag"></groupId></span>
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-tag"><artifactId></span>spring-cloud-stream-test-support<span xmlns:d="http://docbook.org/ns/docbook" class="hl-tag"></artifactId></span>
|
||||
@@ -53,4 +53,4 @@ To do so, you can exclude the <code class="literal">org.springframework.cloud.st
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> String transform(String in) {
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> in + <span xmlns:d="http://docbook.org/ns/docbook" class="hl-string">" world"</span>;
|
||||
}
|
||||
}</pre><p>When autoconfiguration is disabled, the test binder is available on the classpath, and its <code class="literal">defaultCandidate</code> property is set to <code class="literal">false</code> so that it does not interfere with the regular user configuration. It can be referenced under the name, <code class="literal">test</code>, as shown in the following example:</p><p><code class="literal">spring.cloud.stream.defaultBinder=test</code></p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__inter_application_communication.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__health_indicator.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">11. Inter-Application Communication </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 13. Health Indicator</td></tr></table></div></body></html>
|
||||
}</pre><p>When autoconfiguration is disabled, the test binder is available on the classpath, and its <code class="literal">defaultCandidate</code> property is set to <code class="literal">false</code> so that it does not interfere with the regular user configuration. It can be referenced under the name, <code class="literal">test</code>, as shown in the following example:</p><p><code class="literal">spring.cloud.stream.defaultBinder=test</code></p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__inter_application_communication.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__health_indicator.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">11. Inter-Application Communication </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 13. Health Indicator</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>3. What’s New in 2.0?</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__quick_start.html" title="2. Quick Start"><link rel="next" href="multi__reference_guide.html" title="Part II. Reference Guide"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">3. What’s New in 2.0?</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__quick_start.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__reference_guide.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_whats_new_in_2_0" href="#_whats_new_in_2_0"></a>3. What’s New in 2.0?</h2></div></div></div><p>Spring Cloud Stream introduces a number of new features, enhancements, and changes. The following sections outline the most notable ones:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="xref" href="multi__whats_new_in_2_0.html#spring-cloud-stream-preface-new-features" title="3.1 New Features and Components">Section 3.1, “New Features and Components”</a></li><li class="listitem"><a class="xref" href="multi__whats_new_in_2_0.html#spring-cloud-stream-preface-notable-enhancements" title="3.2 Notable Enhancements">Section 3.2, “Notable Enhancements”</a></li></ul></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-preface-new-features" href="#spring-cloud-stream-preface-new-features"></a>3.1 New Features and Components</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>Polling Consumers</strong></span>: Introduction of polled consumers, which lets the application control message processing rates.
|
||||
<title>3. What’s New in 2.0?</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__quick_start.html" title="2. Quick Start"><link rel="next" href="multi_spring-cloud-stream-overview-introducing.html" title="4. Introducing Spring Cloud Stream"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">3. What’s New in 2.0?</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__quick_start.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-introducing.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_whats_new_in_2_0" href="#_whats_new_in_2_0"></a>3. What’s New in 2.0?</h2></div></div></div><p>Spring Cloud Stream introduces a number of new features, enhancements, and changes. The following sections outline the most notable ones:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="xref" href="multi__whats_new_in_2_0.html#spring-cloud-stream-preface-new-features" title="3.1 New Features and Components">Section 3.1, “New Features and Components”</a></li><li class="listitem"><a class="xref" href="multi__whats_new_in_2_0.html#spring-cloud-stream-preface-notable-enhancements" title="3.2 Notable Enhancements">Section 3.2, “Notable Enhancements”</a></li></ul></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-preface-new-features" href="#spring-cloud-stream-preface-new-features"></a>3.1 New Features and Components</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>Polling Consumers</strong></span>: Introduction of polled consumers, which lets the application control message processing rates.
|
||||
See <span class="quote">“<span class="quote"><a class="xref" href="multi__programming_model.html#spring-cloud-streams-overview-using-polled-consumers" title="6.3.5 Using Polled Consumers">Section 6.3.5, “Using Polled Consumers”</a></span>”</span> for more details.
|
||||
You can also read <a class="link" href="https://spring.io/blog/2018/02/27/spring-cloud-stream-2-0-polled-consumers" target="_top">this blog post</a> for more details.</li><li class="listitem"><span class="strong"><strong>Micrometer Support</strong></span>: Metrics has been switched to use <a class="link" href="https://micrometer.io/" target="_top">Micrometer</a>.
|
||||
<code class="literal">MeterRegistry</code> is also provided as a bean so that custom applications can autowire it to capture custom metrics.
|
||||
@@ -22,11 +22,11 @@ See the <span class="quote">“<span class="quote"><a class="xref" href="mul
|
||||
Also <a class="link" href="https://spring.io/blog/2018/02/26/spring-cloud-stream-2-0-content-type-negotiation-and-transformation" target="_top">this blog post</a> contains more detail.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">All message conversion is now handled <span class="strong"><strong>only</strong></span> by <code class="literal">MessageConverter</code> objects.</li><li class="listitem">We introduced the <code class="literal">@StreamMessageConverter</code> annotation to provide custom <code class="literal">MessageConverter</code> objects.</li><li class="listitem">We introduced the default <code class="literal">Content Type</code> as <code class="literal">application/json</code>, which needs to be taken into consideration when migrating 1.3 application or operating in the mixed mode (that is, 1.3 producer → 2.0 consumer).</li><li class="listitem">Messages with textual payloads and a <code class="literal">contentType</code> of <code class="literal">text/…​</code> or <code class="literal">…​/json</code> are no longer converted to <code class="literal">Message<String></code> for cases where the argument type of the provided <code class="literal">MessageHandler</code> can not be determined (that is, <code class="literal">public void handle(Message<?> message)</code> or <code class="literal">public void handle(Object payload)</code>).
|
||||
Furthermore, a strong argument type may not be enough to properly convert messages, so the <code class="literal">contentType</code> header may be used as a supplement by some <code class="literal">MessageConverters</code>.</li></ul></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-preface-notable-deprecations" href="#spring-cloud-stream-preface-notable-deprecations"></a>3.3 Notable Deprecations</h2></div></div></div><p>As of version 2.0, the following items have been deprecated:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="xref" href="multi__whats_new_in_2_0.html#spring-cloud-stream-preface-deprecation-java-serialization" title="3.3.1 Java Serialization (Java Native and Kryo)">Section 3.3.1, “Java Serialization (Java Native and Kryo)”</a></li><li class="listitem"><a class="xref" href="multi__whats_new_in_2_0.html#spring-cloud-stream-preface-deprecation-classes-methods" title="3.3.2 Deprecated Classes and Methods">Section 3.3.2, “Deprecated Classes and Methods”</a></li></ul></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="spring-cloud-stream-preface-deprecation-java-serialization" href="#spring-cloud-stream-preface-deprecation-java-serialization"></a>3.3.1 Java Serialization (Java Native and Kryo)</h3></div></div></div><p><code class="literal">JavaSerializationMessageConverter</code> and <code class="literal">KryoMessageConverter</code> remain for now. However, we plan to move them out of the core packages and support in the future.
|
||||
The main reason for this deprecation is to flag the issue that type-based, language-specific serialization could cause in distributed environments, where Producers and Consumers may depend on different JVM versions or have different versions of supporting libraries (that is, Kryo).
|
||||
We also wanted to draw the attention to the fact that Consumers and Producers may not even be Java-based, so polyglot style serialization (i.e., JSON) is better suited.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="spring-cloud-stream-preface-deprecation-classes-methods" href="#spring-cloud-stream-preface-deprecation-classes-methods"></a>3.3.2 Deprecated Classes and Methods</h3></div></div></div><p>The following is a quick summary of notable deprecations. See the corresponding <a class="link" href="https://docs.spring.io/spring-cloud-stream/docs/current-snapshot/api/" target="_top">javadoc</a> for more details.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">SharedChannelRegistry</code>. Use <code class="literal">SharedBindingTargetRegistry</code>.</li><li class="listitem"><code class="literal">Bindings</code>.
|
||||
We also wanted to draw the attention to the fact that Consumers and Producers may not even be Java-based, so polyglot style serialization (i.e., JSON) is better suited.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="spring-cloud-stream-preface-deprecation-classes-methods" href="#spring-cloud-stream-preface-deprecation-classes-methods"></a>3.3.2 Deprecated Classes and Methods</h3></div></div></div><p>The following is a quick summary of notable deprecations. See the corresponding {spring-cloud-stream-javadoc-current}[javadoc] for more details.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">SharedChannelRegistry</code>. Use <code class="literal">SharedBindingTargetRegistry</code>.</li><li class="listitem"><code class="literal">Bindings</code>.
|
||||
Beans qualified by it are already uniquely identified by their type — for example, provided <code class="literal">Source</code>, <code class="literal">Processor</code>, or custom bindings:</li></ul></div><pre class="screen">public interface Sample {
|
||||
String OUTPUT = "sampleOutput";
|
||||
|
||||
@Output(Sample.OUTPUT)
|
||||
MessageChannel output();
|
||||
}</pre><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">HeaderMode.raw</code>. Use <code class="literal">none</code>, <code class="literal">headers</code> or <code class="literal">embeddedHeaders</code></li><li class="listitem"><code class="literal">ProducerProperties.partitionKeyExtractorClass</code> in favor of <code class="literal">partitionKeyExtractorName</code> and <code class="literal">ProducerProperties.partitionSelectorClass</code> in favor of <code class="literal">partitionSelectorName</code>.
|
||||
This change ensures that both components are Spring configured and managed and are referenced in a Spring-friendly way.</li><li class="listitem"><code class="literal">BinderAwareRouterBeanPostProcessor</code>. While the component remains, it is no longer a <code class="literal">BeanPostProcessor</code> and will be renamed in the future.</li><li class="listitem"><code class="literal">BinderProperties.setEnvironment(Properties environment)</code>. Use <code class="literal">BinderProperties.setEnvironment(Map<String, Object> environment)</code>.</li></ul></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__quick_start.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__reference_guide.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2. Quick Start </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> Part II. Reference Guide</td></tr></table></div></body></html>
|
||||
This change ensures that both components are Spring configured and managed and are referenced in a Spring-friendly way.</li><li class="listitem"><code class="literal">BinderAwareRouterBeanPostProcessor</code>. While the component remains, it is no longer a <code class="literal">BeanPostProcessor</code> and will be renamed in the future.</li><li class="listitem"><code class="literal">BinderProperties.setEnvironment(Properties environment)</code>. Use <code class="literal">BinderProperties.setEnvironment(Map<String, Object> environment)</code>.</li></ul></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__quick_start.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_spring-cloud-stream-overview-introducing.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2. Quick Start </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 4. Introducing Spring Cloud Stream</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>9. Content Type Negotiation</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi__configuration_options.html" title="8. Configuration Options"><link rel="next" href="multi_schema-evolution.html" title="10. Schema Evolution Support"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">9. Content Type Negotiation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__configuration_options.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi_schema-evolution.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="content-type-management" href="#content-type-management"></a>9. Content Type Negotiation</h2></div></div></div><p>Data transformation is one of the core features of any message-driven microservice architecture. Given that, in Spring Cloud Stream, such data
|
||||
<title>9. Content Type Negotiation</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__configuration_options.html" title="8. Configuration Options"><link rel="next" href="multi_schema-evolution.html" title="10. Schema Evolution Support"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">9. Content Type Negotiation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__configuration_options.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi_schema-evolution.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="content-type-management" href="#content-type-management"></a>9. Content Type Negotiation</h2></div></div></div><p>Data transformation is one of the core features of any message-driven microservice architecture. Given that, in Spring Cloud Stream, such data
|
||||
is represented as a Spring <code class="literal">Message</code>, a message may have to be transformed to a desired shape or size before reaching its destination. This is required for two reasons:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">To convert the contents of the incoming message to match the signature of the application-provided handler.</li><li class="listitem">To convert the contents of the outgoing message to the wire format.</li></ol></div><p>The wire format is typically <code class="literal">byte[]</code> (that is true for the Kafka and Rabbit binders), but it is governed by the binder implementation.</p><p>In Spring Cloud Stream, message transformation is accomplished with an <code class="literal">org.springframework.messaging.converter.MessageConverter</code>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>As a supplement to the details to follow, you may also want to read the following <a class="link" href="https://spring.io/blog/2018/02/26/spring-cloud-stream-2-0-content-type-negotiation-and-transformation" target="_top">blog post</a>.</p></td></tr></table></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_mechanics" href="#_mechanics"></a>9.1 Mechanics</h2></div></div></div><p>To better understand the mechanics and the necessity behind content-type negotiation, we take a look at a very simple use case by using the following message handler as an example:</p><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@StreamListener(Processor.INPUT)</span></em>
|
||||
<em><span class="hl-annotation" style="color: gray">@SendTo(Processor.OUTPUT)</span></em>
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> String handle(Person person) {..}</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>For simplicity, we assume that this is the only handler in the application (we assume there is no internal pipeline).</p></td></tr></table></div><p>The handler shown in the preceding example expects a <code class="literal">Person</code> object as an argument and produces a <code class="literal">String</code> type as an output.
|
||||
@@ -75,4 +75,4 @@ Consequently, custom <code class="literal">MessageConverter</code> implementatio
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> (payload <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">instanceof</span> Bar ? payload : <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">new</span> Bar((<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">byte</span>[]) payload));
|
||||
}
|
||||
}</pre><p>Spring Cloud Stream also provides support for Avro-based converters and schema evolution.
|
||||
See <span class="quote">“<span class="quote"><a class="xref" href="multi_schema-evolution.html" title="10. Schema Evolution Support">Chapter 10, <i>Schema Evolution Support</i></a></span>”</span> for details.</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__configuration_options.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_schema-evolution.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">8. Configuration Options </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 10. Schema Evolution Support</td></tr></table></div></body></html>
|
||||
See <span class="quote">“<span class="quote"><a class="xref" href="multi_schema-evolution.html" title="10. Schema Evolution Support">Chapter 10, <i>Schema Evolution Support</i></a></span>”</span> for details.</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__configuration_options.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi_schema-evolution.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">8. Configuration Options </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 10. Schema Evolution Support</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>10. Schema Evolution Support</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi_content-type-management.html" title="9. Content Type Negotiation"><link rel="next" href="multi__inter_application_communication.html" title="11. Inter-Application Communication"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">10. Schema Evolution Support</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_content-type-management.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__inter_application_communication.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="schema-evolution" href="#schema-evolution"></a>10. Schema Evolution Support</h2></div></div></div><p>Spring Cloud Stream provides support for schema evolution so that the data can be evolved over time and still work with older or newer producers and consumers and vice versa.
|
||||
<title>10. Schema Evolution Support</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi_content-type-management.html" title="9. Content Type Negotiation"><link rel="next" href="multi__inter_application_communication.html" title="11. Inter-Application Communication"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">10. Schema Evolution Support</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi_content-type-management.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__inter_application_communication.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="schema-evolution" href="#schema-evolution"></a>10. Schema Evolution Support</h2></div></div></div><p>Spring Cloud Stream provides support for schema evolution so that the data can be evolved over time and still work with older or newer producers and consumers and vice versa.
|
||||
Most serialization models, especially the ones that aim for portability across different platforms and languages, rely on a schema that describes how the data is serialized in the binary payload.
|
||||
In order to serialize the data and then to interpret it, both the sending and receiving sides must have access to a schema that describes the binary format.
|
||||
In certain cases, the schema can be inferred from the payload type on serialization or from the target type on deserialization.
|
||||
@@ -23,7 +23,7 @@ A schema is referenceable as a tuple consisting of:</p><div class="itemizedlist"
|
||||
Because of this, it uses a <code class="literal">DefaultSchemaRegistryClient</code> that does not cache responses.
|
||||
If you intend to change the default behavior, you can use the client directly on your code and override it to the desired outcome.
|
||||
To do so, you have to add the property <code class="literal">spring.cloud.stream.schemaRegistryClient.cached=true</code> to your application properties.</p></td></tr></table></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_schema_registry_client_properties" href="#_schema_registry_client_properties"></a>10.1.1 Schema Registry Client Properties</h3></div></div></div><p>The Schema Registry Client supports the following properties:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">spring.cloud.stream.schemaRegistryClient.endpoint</code></span></dt><dd>The location of the schema-server.
|
||||
When setting this, use a full URL, including protocol (<code class="literal">http</code> or <code class="literal">https</code>) , port, and context path.</dd><dt><span class="term">Default</span></dt><dd><code class="literal"><a class="link" href="http://localhost:8990/" target="_top">localhost:8990/</a></code></dd><dt><span class="term"><code class="literal">spring.cloud.stream.schemaRegistryClient.cached</code></span></dt><dd>Whether the client should cache schema server responses.
|
||||
When setting this, use a full URL, including protocol (<code class="literal">http</code> or <code class="literal">https</code>) , port, and context path.</dd><dt><span class="term">Default</span></dt><dd><code class="literal"><a class="link" href="http://localhost:8990/" target="_top">http://localhost:8990/</a></code></dd><dt><span class="term"><code class="literal">spring.cloud.stream.schemaRegistryClient.cached</code></span></dt><dd>Whether the client should cache schema server responses.
|
||||
Normally set to <code class="literal">false</code>, as the caching happens in the message converter.
|
||||
Clients using the schema registry client should set this to <code class="literal">true</code>.</dd><dt><span class="term">Default</span></dt><dd><code class="literal">false</code></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_avro_schema_registry_client_message_converters" href="#_avro_schema_registry_client_message_converters"></a>10.2 Avro Schema Registry Client Message Converters</h2></div></div></div><p>For applications that have a SchemaRegistryClient bean registered with the application context, Spring Cloud Stream auto configures an Apache Avro message converter for schema management.
|
||||
This eases schema evolution, as applications that receive messages can get easy access to a writer schema that can be reconciled with their own reader schema.</p><p>For outbound messages, if the content type of the channel is set to <code class="literal">application/*+avro</code>, the <code class="literal">MessageConverter</code> is activated, as shown in the following example:</p><pre class="programlisting"><span xmlns:d="http://docbook.org/ns/docbook" class="hl-attribute">spring.cloud.stream.bindings.output.contentType</span>=application/*+avro</pre><p>During the outbound conversion, the message converter tries to infer the schema of each outbound messages (based on its type) and register it to a subject (based on the payload type) by using the <code class="literal">SchemaRegistryClient</code>.
|
||||
@@ -79,10 +79,10 @@ If you want to use the Confluent schema registry, you need to create a bean of t
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> client;
|
||||
}</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>The ConfluentSchemaRegistryClient is tested against Confluent platform version 4.0.0.</p></td></tr></table></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_schema_registration_and_resolution" href="#_schema_registration_and_resolution"></a>10.6 Schema Registration and Resolution</h2></div></div></div><p>To better understand how Spring Cloud Stream registers and resolves new schemas and its use of Avro schema comparison features, we provide two separate subsections:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi_schema-evolution.html#spring-cloud-stream-overview-schema-registration-process" title="10.6.1 Schema Registration Process (Serialization)">Section 10.6.1, “Schema Registration Process (Serialization)”</a></span>”</span></li><li class="listitem"><span class="quote">“<span class="quote"><a class="xref" href="multi_schema-evolution.html#spring-cloud-stream-overview-schema-resolution-process" title="10.6.2 Schema Resolution Process (Deserialization)">Section 10.6.2, “Schema Resolution Process (Deserialization)”</a></span>”</span></li></ul></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="spring-cloud-stream-overview-schema-registration-process" href="#spring-cloud-stream-overview-schema-registration-process"></a>10.6.1 Schema Registration Process (Serialization)</h3></div></div></div><p>The first part of the registration process is extracting a schema from the payload that is being sent over a channel.
|
||||
Avro types such as <code class="literal">SpecificRecord</code> or <code class="literal">GenericRecord</code> already contain a schema, which can be retrieved immediately from the instance.
|
||||
In the case of POJOs, a schema is inferred if the <code class="literal">spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled</code> property is set to <code class="literal">true</code> (the default).</p><div class="figure"><a name="d0e4098" href="#d0e4098"></a><p class="title"><b>Figure 10.1. Schema Writer Resolution Process</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/schema_resolution.png" align="middle" alt="schema resolution"></div></div></div><br class="figure-break"><p>Ones a schema is obtained, the converter loads its metadata (version) from the remote server.
|
||||
In the case of POJOs, a schema is inferred if the <code class="literal">spring.cloud.stream.schema.avro.dynamicSchemaGenerationEnabled</code> property is set to <code class="literal">true</code> (the default).</p><div class="figure"><a name="d0e4089" href="#d0e4089"></a><p class="title"><b>Figure 10.1. Schema Writer Resolution Process</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/schema_resolution.png" align="middle" alt="schema resolution"></div></div></div><br class="figure-break"><p>Ones a schema is obtained, the converter loads its metadata (version) from the remote server.
|
||||
First, it queries a local cache. If no result is found, it submits the data to the server, which replies with versioning information.
|
||||
The converter always caches the results to avoid the overhead of querying the Schema Server for every new message that needs to be serialized.</p><div class="figure"><a name="d0e4109" href="#d0e4109"></a><p class="title"><b>Figure 10.2. Schema Registration Process</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/registration.png" align="middle" alt="registration"></div></div></div><br class="figure-break"><p>With the schema version information, the converter sets the <code class="literal">contentType</code> header of the message to carry the version information — for example: <code class="literal">application/vnd.user.v1+avro</code>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="spring-cloud-stream-overview-schema-resolution-process" href="#spring-cloud-stream-overview-schema-resolution-process"></a>10.6.2 Schema Resolution Process (Deserialization)</h3></div></div></div><p>When reading messages that contain version information (that is, a <code class="literal">contentType</code> header with a scheme like the one described under <span class="quote">“<span class="quote"><a class="xref" href="multi_schema-evolution.html#spring-cloud-stream-overview-schema-registration-process" title="10.6.1 Schema Registration Process (Serialization)">Section 10.6.1, “Schema Registration Process (Serialization)”</a></span>”</span>), the converter queries the Schema server to fetch the writer schema of the message.
|
||||
Once it has found the correct schema of the incoming message, it retrieves the reader schema and, by using Avro’s schema resolution support, reads it into the reader definition (setting defaults and any missing properties).</p><div class="figure"><a name="d0e4137" href="#d0e4137"></a><p class="title"><b>Figure 10.3. Schema Reading Resolution Process</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/schema_reading.png" align="middle" alt="schema reading"></div></div></div><br class="figure-break"><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>You should understand the difference between a writer schema (the application that wrote the message) and a reader schema (the receiving application).
|
||||
The converter always caches the results to avoid the overhead of querying the Schema Server for every new message that needs to be serialized.</p><div class="figure"><a name="d0e4100" href="#d0e4100"></a><p class="title"><b>Figure 10.2. Schema Registration Process</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/registration.png" align="middle" alt="registration"></div></div></div><br class="figure-break"><p>With the schema version information, the converter sets the <code class="literal">contentType</code> header of the message to carry the version information — for example: <code class="literal">application/vnd.user.v1+avro</code>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="spring-cloud-stream-overview-schema-resolution-process" href="#spring-cloud-stream-overview-schema-resolution-process"></a>10.6.2 Schema Resolution Process (Deserialization)</h3></div></div></div><p>When reading messages that contain version information (that is, a <code class="literal">contentType</code> header with a scheme like the one described under <span class="quote">“<span class="quote"><a class="xref" href="multi_schema-evolution.html#spring-cloud-stream-overview-schema-registration-process" title="10.6.1 Schema Registration Process (Serialization)">Section 10.6.1, “Schema Registration Process (Serialization)”</a></span>”</span>), the converter queries the Schema server to fetch the writer schema of the message.
|
||||
Once it has found the correct schema of the incoming message, it retrieves the reader schema and, by using Avro’s schema resolution support, reads it into the reader definition (setting defaults and any missing properties).</p><div class="figure"><a name="d0e4128" href="#d0e4128"></a><p class="title"><b>Figure 10.3. Schema Reading Resolution Process</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/schema_reading.png" align="middle" alt="schema reading"></div></div></div><br class="figure-break"><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>You should understand the difference between a writer schema (the application that wrote the message) and a reader schema (the receiving application).
|
||||
We suggest taking a moment to read <a class="link" href="https://avro.apache.org/docs/1.7.6/spec.html" target="_top">the Avro terminology</a> and understand the process.
|
||||
Spring Cloud Stream always fetches the writer schema to determine how to read a message.
|
||||
If you want to get Avro’s schema evolution support working, you need to make sure that a <code class="literal">readerSchema</code> was properly set for your application.</p></td></tr></table></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_content-type-management.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__inter_application_communication.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">9. Content Type Negotiation </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 11. Inter-Application Communication</td></tr></table></div></body></html>
|
||||
If you want to get Avro’s schema evolution support working, you need to make sure that a <code class="literal">readerSchema</code> was properly set for your application.</p></td></tr></table></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi_content-type-management.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__inter_application_communication.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">9. Content Type Negotiation </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 11. Inter-Application Communication</td></tr></table></div></body></html>
|
||||
@@ -1,7 +1,7 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>7. Binders</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi__programming_model.html" title="6. Programming Model"><link rel="next" href="multi__configuration_options.html" title="8. Configuration Options"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">7. Binders</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__programming_model.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__configuration_options.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="spring-cloud-stream-overview-binders" href="#spring-cloud-stream-overview-binders"></a>7. Binders</h2></div></div></div><p>Spring Cloud Stream provides a Binder abstraction for use in connecting to physical destinations at the external middleware.
|
||||
This section provides information about the main concepts behind the Binder SPI, its main components, and implementation-specific details.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_producers_and_consumers" href="#_producers_and_consumers"></a>7.1 Producers and Consumers</h2></div></div></div><p>The following image shows the general relationship of producers and consumers:</p><div class="figure"><a name="d0e2046" href="#d0e2046"></a><p class="title"><b>Figure 7.1. Producers and Consumers</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/producers-consumers.png" align="middle" alt="producers consumers"></div></div></div><br class="figure-break"><p>A producer is any component that sends messages to a channel.
|
||||
<title>7. Binders</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__programming_model.html" title="6. Programming Model"><link rel="next" href="multi__configuration_options.html" title="8. Configuration Options"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">7. Binders</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__programming_model.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__configuration_options.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="spring-cloud-stream-overview-binders" href="#spring-cloud-stream-overview-binders"></a>7. Binders</h2></div></div></div><p>Spring Cloud Stream provides a Binder abstraction for use in connecting to physical destinations at the external middleware.
|
||||
This section provides information about the main concepts behind the Binder SPI, its main components, and implementation-specific details.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_producers_and_consumers" href="#_producers_and_consumers"></a>7.1 Producers and Consumers</h2></div></div></div><p>The following image shows the general relationship of producers and consumers:</p><div class="figure"><a name="d0e2037" href="#d0e2037"></a><p class="title"><b>Figure 7.1. Producers and Consumers</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="https://raw.githubusercontent.com/spring-cloud/spring-cloud-stream/master/docs/src/main/asciidoc/images/producers-consumers.png" align="middle" alt="producers consumers"></div></div></div><br class="figure-break"><p>A producer is any component that sends messages to a channel.
|
||||
The channel can be bound to an external message broker with a <code class="literal">Binder</code> implementation for that broker.
|
||||
When invoking the <code class="literal">bindProducer()</code> method, the first parameter is the name of the destination within the broker, the second parameter is the local channel instance to which the producer sends messages, and the third parameter contains properties (such as a partition key expression) to be used within the adapter that is created for that channel.</p><p>A consumer is any component that receives messages from a channel.
|
||||
As with a producer, the consumer’s channel can be bound to an external message broker.
|
||||
@@ -64,13 +64,13 @@ The following example shows how to add the dependency for the Web framework:</p>
|
||||
application will not start due to health check failures.</p></td></tr></table></div><p>You must also enable the <code class="literal">bindings</code> actuator endpoints by setting the following property: <code class="literal">--management.endpoints.web.exposure.include=bindings</code>.</p><p>Once those prerequisites are satisfied. you should see the following in the logs when application start:</p><pre class="literallayout">: Mapped "{[/actuator/bindings/{name}],methods=[POST]. . .
|
||||
: Mapped "{[/actuator/bindings],methods=[GET]. . .
|
||||
: Mapped "{[/actuator/bindings/{name}],methods=[GET]. . .</pre><p>To visualize the current bindings, access the following URL:
|
||||
<code class="literal"><a class="link" href="http://<host>:<port>/actuator/bindings" target="_top"><host>:<port>/actuator/bindings</a></code></p><p>Alternative, to see a single binding, access one of the URLs similar to the following:
|
||||
<code class="literal"><a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top"><host>:<port>/actuator/bindings/myBindingName</a></code></p><p>You can also stop, start, pause, and resume individual bindings by posting to the same URL while providing a <code class="literal">state</code> argument as JSON, as shown in the following examples:</p><p>curl -d '{"state":"STOPPED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top"><host>:<port>/actuator/bindings/myBindingName</a>
|
||||
curl -d '{"state":"STARTED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top"><host>:<port>/actuator/bindings/myBindingName</a>
|
||||
curl -d '{"state":"PAUSED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top"><host>:<port>/actuator/bindings/myBindingName</a>
|
||||
curl -d '{"state":"RESUMED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top"><host>:<port>/actuator/bindings/myBindingName</a></p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p><code class="literal">PAUSED</code> and <code class="literal">RESUMED</code> work only when the corresponding binder and its underlying technology supports it. Otherwise, you see the warning message in the logs.
|
||||
<code class="literal"><a class="link" href="http://<host>:<port>/actuator/bindings" target="_top">http://<host>:<port>/actuator/bindings</a></code></p><p>Alternative, to see a single binding, access one of the URLs similar to the following:
|
||||
<code class="literal"><a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top">http://<host>:<port>/actuator/bindings/myBindingName</a></code></p><p>You can also stop, start, pause, and resume individual bindings by posting to the same URL while providing a <code class="literal">state</code> argument as JSON, as shown in the following examples:</p><p>curl -d '{"state":"STOPPED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top">http://<host>:<port>/actuator/bindings/myBindingName</a>
|
||||
curl -d '{"state":"STARTED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top">http://<host>:<port>/actuator/bindings/myBindingName</a>
|
||||
curl -d '{"state":"PAUSED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top">http://<host>:<port>/actuator/bindings/myBindingName</a>
|
||||
curl -d '{"state":"RESUMED"}' -H "Content-Type: application/json" -X POST <a class="link" href="http://<host>:<port>/actuator/bindings/myBindingName" target="_top">http://<host>:<port>/actuator/bindings/myBindingName</a></p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p><code class="literal">PAUSED</code> and <code class="literal">RESUMED</code> work only when the corresponding binder and its underlying technology supports it. Otherwise, you see the warning message in the logs.
|
||||
Currently, only Kafka binder supports the <code class="literal">PAUSED</code> and <code class="literal">RESUMED</code> states.</p></td></tr></table></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="_binder_configuration_properties" href="#_binder_configuration_properties"></a>7.7 Binder Configuration Properties</h2></div></div></div><p>The following properties are available when customizing binder configurations. These properties exposed via <code class="literal">org.springframework.cloud.stream.config.BinderProperties</code></p><p>They must be prefixed with <code class="literal">spring.cloud.stream.binders.<configurationName></code>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">type</span></dt><dd><p class="simpara">The binder type.
|
||||
It typically references one of the binders found on the classpath — in particular, a key in a <code class="literal">META-INF/spring.binders</code> file.</p><p class="simpara">By default, it has the same value as the configuration name.</p></dd><dt><span class="term">inheritEnvironment</span></dt><dd><p class="simpara">Whether the configuration inherits the environment of the application itself.</p><p class="simpara">Default: <code class="literal">true</code>.</p></dd><dt><span class="term">environment</span></dt><dd><p class="simpara">Root for a set of properties that can be used to customize the environment of the binder.
|
||||
When this property is set, the context in which the binder is being created is not a child of the application context.
|
||||
This setting allows for complete separation between the binder components and the application components.</p><p class="simpara">Default: <code class="literal">empty</code>.</p></dd><dt><span class="term">defaultCandidate</span></dt><dd><p class="simpara">Whether the binder configuration is a candidate for being considered a default binder or can be used only when explicitly referenced.
|
||||
This setting allows adding binder configurations without interfering with the default processing.</p><p class="simpara">Default: <code class="literal">true</code>.</p></dd></dl></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__programming_model.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__configuration_options.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">6. Programming Model </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 8. Configuration Options</td></tr></table></div></body></html>
|
||||
This setting allows adding binder configurations without interfering with the default processing.</p><p class="simpara">Default: <code class="literal">true</code>.</p></dd></dl></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__programming_model.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__configuration_options.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">6. Programming Model </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 8. Configuration Options</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>4. Introducing Spring Cloud Stream</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="next" href="multi__main_concepts.html" title="5. Main Concepts"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">4. Introducing Spring Cloud Stream</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__reference_guide.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__main_concepts.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="spring-cloud-stream-overview-introducing" href="#spring-cloud-stream-overview-introducing"></a>4. Introducing Spring Cloud Stream</h2></div></div></div><p>Spring Cloud Stream is a framework for building message-driven microservice applications.
|
||||
<title>4. Introducing Spring Cloud Stream</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__whats_new_in_2_0.html" title="3. What’s New in 2.0?"><link rel="next" href="multi__main_concepts.html" title="5. Main Concepts"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">4. Introducing Spring Cloud Stream</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__whats_new_in_2_0.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__main_concepts.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="spring-cloud-stream-overview-introducing" href="#spring-cloud-stream-overview-introducing"></a>4. Introducing Spring Cloud Stream</h2></div></div></div><p>Spring Cloud Stream is a framework for building message-driven microservice applications.
|
||||
Spring Cloud Stream builds upon Spring Boot to create standalone, production-grade Spring applications and uses Spring Integration to provide connectivity to message brokers.
|
||||
It provides opinionated configuration of middleware from several vendors, introducing the concepts of persistent publish-subscribe semantics, consumer groups, and partitions.</p><p>You can add the <code class="literal">@EnableBinding</code> annotation to your application to get immediate connectivity to a message broker, and you can add <code class="literal">@StreamListener</code> to a method to cause it to receive events for stream processing.
|
||||
The following example shows a sink application that receives external messages:</p><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@SpringBootApplication</span></em>
|
||||
@@ -39,4 +39,4 @@ You can use this in the application by autowiring it, as shown in the following
|
||||
<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">void</span> contextLoads() {
|
||||
assertNotNull(<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">this</span>.sink.input());
|
||||
}
|
||||
}</pre></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__reference_guide.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__main_concepts.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Part II. Reference Guide </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 5. Main Concepts</td></tr></table></div></body></html>
|
||||
}</pre></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__whats_new_in_2_0.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__main_concepts.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">3. What’s New in 2.0? </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 5. Main Concepts</td></tr></table></div></body></html>
|
||||
@@ -1,6 +1,6 @@
|
||||
<html><head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>14. Metrics Emitter</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__reference_guide.html" title="Part II. Reference Guide"><link rel="prev" href="multi__health_indicator.html" title="13. Health Indicator"><link rel="next" href="multi__samples.html" title="15. Samples"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">14. Metrics Emitter</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__health_indicator.html">Prev</a> </td><th width="60%" align="center">Part II. Reference Guide</th><td width="20%" align="right"> <a accesskey="n" href="multi__samples.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="spring-cloud-stream-overview-metrics-emitter" href="#spring-cloud-stream-overview-metrics-emitter"></a>14. Metrics Emitter</h2></div></div></div><p>Spring Boot Actuator provides dependency management and auto-configuration for <a class="link" href="https://micrometer.io/" target="_top">Micrometer</a>, an application metrics
|
||||
<title>14. Metrics Emitter</title><link rel="stylesheet" type="text/css" href="css/manual-multipage.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="multi_spring-cloud-stream.html" title="Spring Cloud Stream Reference Guide"><link rel="up" href="multi__preface.html" title="Part I. Preface"><link rel="prev" href="multi__health_indicator.html" title="13. Health Indicator"><link rel="next" href="multi__samples.html" title="15. Samples"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">14. Metrics Emitter</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__health_indicator.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__samples.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="spring-cloud-stream-overview-metrics-emitter" href="#spring-cloud-stream-overview-metrics-emitter"></a>14. Metrics Emitter</h2></div></div></div><p>Spring Boot Actuator provides dependency management and auto-configuration for <a class="link" href="https://micrometer.io/" target="_top">Micrometer</a>, an application metrics
|
||||
facade that supports numerous <a class="link" href="https://docs.spring.io/spring-boot/docs/2.0.0.RELEASE/reference/htmlsingle/#production-ready-metrics" target="_top">monitoring systems</a>.</p><p>Spring Cloud Stream provides support for emitting any available micrometer-based metrics to a binding destination, allowing for periodic
|
||||
collection of metric data from stream applications without relying on polling individual endpoints.</p><p>Metrics Emitter is activated by defining the <code class="literal">spring.cloud.stream.bindings.applicationMetrics.destination</code> property,
|
||||
which specifies the name of the binding destination used by the current binder to publish metric messages.</p><p>For example:</p><pre class="programlisting">spring.cloud.stream.bindings.applicationMetrics.destination=myMetricDestination</pre><p>The preceding example instructs the binder to bind to <code class="literal">myMetricDestination</code> (that is, Rabbit exchange, Kafka topic, and others).</p><p>The following properties can be used for customizing the emission of metrics:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">spring.cloud.stream.metrics.key</span></dt><dd><p class="simpara">The name of the metric being emitted. Should be a unique value per application.</p><p class="simpara">Default: <code class="literal">${spring.application.name:${vcap.application.name:${spring.config.name:application}}}</code></p></dd><dt><span class="term">spring.cloud.stream.metrics.properties</span></dt><dd><p class="simpara">Allows white listing application properties that are added to the metrics payload</p><p class="simpara">Default: null.</p></dd><dt><span class="term">spring.cloud.stream.metrics.meter-filter</span></dt><dd><p class="simpara">Pattern to control the 'meters' one wants to capture.
|
||||
@@ -47,4 +47,4 @@ For example, specifying <code class="literal">spring.integration.*</code> captur
|
||||
}
|
||||
]
|
||||
}</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p>Given that the format of the Metric message has slightly changed after migrating to Micrometer, the published message will also have
|
||||
a <code class="literal">STREAM_CLOUD_STREAM_VERSION</code> header set to <code class="literal">2.x</code> to help distinguish between Metric messages from the older versions of the Spring Cloud Stream.</p></td></tr></table></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__health_indicator.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__reference_guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__samples.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">13. Health Indicator </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 15. Samples</td></tr></table></div></body></html>
|
||||
a <code class="literal">STREAM_CLOUD_STREAM_VERSION</code> header set to <code class="literal">2.x</code> to help distinguish between Metric messages from the older versions of the Spring Cloud Stream.</p></td></tr></table></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__health_indicator.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="multi__preface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="multi__samples.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">13. Health Indicator </td><td width="20%" align="center"><a accesskey="h" href="multi_spring-cloud-stream.html">Home</a></td><td width="40%" align="right" valign="top"> 15. Samples</td></tr></table></div></body></html>
|
||||
File diff suppressed because one or more lines are too long
File diff suppressed because one or more lines are too long
@@ -1,5 +1,5 @@
|
||||
<?xml version="1.0" encoding="UTF-8"?>
|
||||
<?asciidoc-toc maxdepth="4"?>
|
||||
<?asciidoc-toc maxdepth="8"?>
|
||||
<?asciidoc-numbered?>
|
||||
<book xmlns="http://docbook.org/ns/docbook" xmlns:xl="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en">
|
||||
<info>
|
||||
@@ -376,7 +376,7 @@ We also wanted to draw the attention to the fact that Consumers and Producers ma
|
||||
</section>
|
||||
<section xml:id="spring-cloud-stream-preface-deprecation-classes-methods">
|
||||
<title>Deprecated Classes and Methods</title>
|
||||
<simpara>The following is a quick summary of notable deprecations. See the corresponding <link xl:href="https://docs.spring.io/spring-cloud-stream/docs/current-snapshot/api/">javadoc</link> for more details.</simpara>
|
||||
<simpara>The following is a quick summary of notable deprecations. See the corresponding {spring-cloud-stream-javadoc-current}[javadoc] for more details.</simpara>
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<simpara><literal>SharedChannelRegistry</literal>. Use <literal>SharedBindingTargetRegistry</literal>.</simpara>
|
||||
@@ -407,16 +407,10 @@ This change ensures that both components are Spring configured and managed and a
|
||||
<simpara><literal>BinderProperties.setEnvironment(Properties environment)</literal>. Use <literal>BinderProperties.setEnvironment(Map<String, Object> environment)</literal>.</simpara>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
|
||||
</section>
|
||||
</section>
|
||||
</chapter>
|
||||
</part>
|
||||
<part xml:id="_reference_guide">
|
||||
<title>Reference Guide</title>
|
||||
<partintro>
|
||||
<simpara>This section goes into more detail about how you can work with Spring Cloud Stream.
|
||||
It covers topics such as creating and running stream applications.</simpara>
|
||||
</partintro>
|
||||
<chapter xml:id="spring-cloud-stream-overview-introducing">
|
||||
<title>Introducing Spring Cloud Stream</title>
|
||||
<simpara>Spring Cloud Stream is a framework for building message-driven microservice applications.
|
||||
@@ -1533,14 +1527,14 @@ application will not start due to health check failures.</simpara>
|
||||
: Mapped "{[/actuator/bindings],methods=[GET]. . .
|
||||
: Mapped "{[/actuator/bindings/{name}],methods=[GET]. . .</literallayout>
|
||||
<simpara>To visualize the current bindings, access the following URL:
|
||||
<literal><link xl:href="http://<host>:<port>/actuator/bindings"><host>:<port>/actuator/bindings</link></literal></simpara>
|
||||
<literal><link xl:href="http://<host>:<port>/actuator/bindings">http://<host>:<port>/actuator/bindings</link></literal></simpara>
|
||||
<simpara>Alternative, to see a single binding, access one of the URLs similar to the following:
|
||||
<literal><link xl:href="http://<host>:<port>/actuator/bindings/myBindingName"><host>:<port>/actuator/bindings/myBindingName</link></literal></simpara>
|
||||
<literal><link xl:href="http://<host>:<port>/actuator/bindings/myBindingName">http://<host>:<port>/actuator/bindings/myBindingName</link></literal></simpara>
|
||||
<simpara>You can also stop, start, pause, and resume individual bindings by posting to the same URL while providing a <literal>state</literal> argument as JSON, as shown in the following examples:</simpara>
|
||||
<simpara>curl -d '{"state":"STOPPED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName"><host>:<port>/actuator/bindings/myBindingName</link>
|
||||
curl -d '{"state":"STARTED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName"><host>:<port>/actuator/bindings/myBindingName</link>
|
||||
curl -d '{"state":"PAUSED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName"><host>:<port>/actuator/bindings/myBindingName</link>
|
||||
curl -d '{"state":"RESUMED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName"><host>:<port>/actuator/bindings/myBindingName</link></simpara>
|
||||
<simpara>curl -d '{"state":"STOPPED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName">http://<host>:<port>/actuator/bindings/myBindingName</link>
|
||||
curl -d '{"state":"STARTED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName">http://<host>:<port>/actuator/bindings/myBindingName</link>
|
||||
curl -d '{"state":"PAUSED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName">http://<host>:<port>/actuator/bindings/myBindingName</link>
|
||||
curl -d '{"state":"RESUMED"}' -H "Content-Type: application/json" -X POST <link xl:href="http://<host>:<port>/actuator/bindings/myBindingName">http://<host>:<port>/actuator/bindings/myBindingName</link></simpara>
|
||||
<note>
|
||||
<simpara><literal>PAUSED</literal> and <literal>RESUMED</literal> work only when the corresponding binder and its underlying technology supports it. Otherwise, you see the warning message in the logs.
|
||||
Currently, only Kafka binder supports the <literal>PAUSED</literal> and <literal>RESUMED</literal> states.</simpara>
|
||||
@@ -2223,7 +2217,7 @@ When setting this, use a full URL, including protocol (<literal>http</literal> o
|
||||
<varlistentry>
|
||||
<term>Default</term>
|
||||
<listitem>
|
||||
<simpara><literal><link xl:href="http://localhost:8990/">localhost:8990/</link></literal></simpara>
|
||||
<simpara><literal><link xl:href="http://localhost:8990/">http://localhost:8990/</link></literal></simpara>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
<varlistentry>
|
||||
@@ -2876,140 +2870,4 @@ a <literal>STREAM_CLOUD_STREAM_VERSION</literal> header set to <literal>2.x</lit
|
||||
</section>
|
||||
</chapter>
|
||||
</part>
|
||||
<part xml:id="_appendices">
|
||||
<title>Appendices</title>
|
||||
<appendix xml:id="building">
|
||||
<title>Building</title>
|
||||
<section xml:id="_basic_compile_and_test">
|
||||
<title>Basic Compile and Test</title>
|
||||
<simpara>To build the source you will need to install JDK 1.7.</simpara>
|
||||
<simpara>The build uses the Maven wrapper so you don’t have to install a specific
|
||||
version of Maven. To enable the tests for Redis, Rabbit, and Kafka bindings you
|
||||
should have those servers running before building. See below for more
|
||||
information on running the servers.</simpara>
|
||||
<simpara>The main build command is</simpara>
|
||||
<screen>$ ./mvnw clean install</screen>
|
||||
<simpara>You can also add '-DskipTests' if you like, to avoid running the tests.</simpara>
|
||||
<note>
|
||||
<simpara>You can also install Maven (>=3.3.3) yourself and run the <literal>mvn</literal> command
|
||||
in place of <literal>./mvnw</literal> in the examples below. If you do that you also
|
||||
might need to add <literal>-P spring</literal> if your local Maven settings do not
|
||||
contain repository declarations for spring pre-release artifacts.</simpara>
|
||||
</note>
|
||||
<note>
|
||||
<simpara>Be aware that you might need to increase the amount of memory
|
||||
available to Maven by setting a <literal>MAVEN_OPTS</literal> environment variable with
|
||||
a value like <literal>-Xmx512m -XX:MaxPermSize=128m</literal>. We try to cover this in
|
||||
the <literal>.mvn</literal> configuration, so if you find you have to do it to make a
|
||||
build succeed, please raise a ticket to get the settings added to
|
||||
source control.</simpara>
|
||||
</note>
|
||||
<simpara>The projects that require middleware generally include a
|
||||
<literal>docker-compose.yml</literal>, so consider using
|
||||
<link xl:href="http://compose.docker.io/">Docker Compose</link> to run the middeware servers
|
||||
in Docker containers. See the README in the
|
||||
<link xl:href="https://github.com/spring-cloud-samples/scripts">scripts demo
|
||||
repository</link> for specific instructions about the common cases of mongo,
|
||||
rabbit and redis.</simpara>
|
||||
</section>
|
||||
<section xml:id="_documentation">
|
||||
<title>Documentation</title>
|
||||
<simpara>There is a "full" profile that will generate documentation.</simpara>
|
||||
</section>
|
||||
<section xml:id="_working_with_the_code">
|
||||
<title>Working with the code</title>
|
||||
<simpara>If you don’t have an IDE preference we would recommend that you use
|
||||
<link xl:href="http://www.springsource.com/developer/sts">Spring Tools Suite</link> or
|
||||
<link xl:href="http://eclipse.org">Eclipse</link> when working with the code. We use the
|
||||
<link xl:href="http://eclipse.org/m2e/">m2eclipe</link> eclipse plugin for maven support. Other IDEs and tools
|
||||
should also work without issue.</simpara>
|
||||
<section xml:id="_importing_into_eclipse_with_m2eclipse">
|
||||
<title>Importing into eclipse with m2eclipse</title>
|
||||
<simpara>We recommend the <link xl:href="http://eclipse.org/m2e/">m2eclipe</link> eclipse plugin when working with
|
||||
eclipse. If you don’t already have m2eclipse installed it is available from the "eclipse
|
||||
marketplace".</simpara>
|
||||
<simpara>Unfortunately m2e does not yet support Maven 3.3, so once the projects
|
||||
are imported into Eclipse you will also need to tell m2eclipse to use
|
||||
the <literal>.settings.xml</literal> file for the projects. If you do not do this you
|
||||
may see many different errors related to the POMs in the
|
||||
projects. Open your Eclipse preferences, expand the Maven
|
||||
preferences, and select User Settings. In the User Settings field
|
||||
click Browse and navigate to the Spring Cloud project you imported
|
||||
selecting the <literal>.settings.xml</literal> file in that project. Click Apply and
|
||||
then OK to save the preference changes.</simpara>
|
||||
<note>
|
||||
<simpara>Alternatively you can copy the repository settings from <link xl:href="https://github.com/spring-cloud/spring-cloud-build/blob/master/.settings.xml"><literal>.settings.xml</literal></link> into your own <literal>~/.m2/settings.xml</literal>.</simpara>
|
||||
</note>
|
||||
</section>
|
||||
<section xml:id="_importing_into_eclipse_without_m2eclipse">
|
||||
<title>Importing into eclipse without m2eclipse</title>
|
||||
<simpara>If you prefer not to use m2eclipse you can generate eclipse project metadata using the
|
||||
following command:</simpara>
|
||||
<screen>$ ./mvnw eclipse:eclipse</screen>
|
||||
<simpara>The generated eclipse projects can be imported by selecting <literal>import existing projects</literal>
|
||||
from the <literal>file</literal> menu.
|
||||
[[contributing]
|
||||
== Contributing</simpara>
|
||||
<simpara>Spring Cloud is released under the non-restrictive Apache 2.0 license,
|
||||
and follows a very standard Github development process, using Github
|
||||
tracker for issues and merging pull requests into master. If you want
|
||||
to contribute even something trivial please do not hesitate, but
|
||||
follow the guidelines below.</simpara>
|
||||
</section>
|
||||
</section>
|
||||
<section xml:id="_sign_the_contributor_license_agreement">
|
||||
<title>Sign the Contributor License Agreement</title>
|
||||
<simpara>Before we accept a non-trivial patch or pull request we will need you to sign the
|
||||
<link xl:href="https://support.springsource.com/spring_committer_signup">contributor’s agreement</link>.
|
||||
Signing the contributor’s agreement does not grant anyone commit rights to the main
|
||||
repository, but it does mean that we can accept your contributions, and you will get an
|
||||
author credit if we do. Active contributors might be asked to join the core team, and
|
||||
given the ability to merge pull requests.</simpara>
|
||||
</section>
|
||||
<section xml:id="_code_conventions_and_housekeeping">
|
||||
<title>Code Conventions and Housekeeping</title>
|
||||
<simpara>None of these is essential for a pull request, but they will all help. They can also be
|
||||
added after the original pull request but before a merge.</simpara>
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<simpara>Use the Spring Framework code format conventions. If you use Eclipse
|
||||
you can import formatter settings using the
|
||||
<literal>eclipse-code-formatter.xml</literal> file from the
|
||||
<link xl:href="https://github.com/spring-cloud/build/tree/master/eclipse-coding-conventions.xml">Spring
|
||||
Cloud Build</link> project. If using IntelliJ, you can use the
|
||||
<link xl:href="http://plugins.jetbrains.com/plugin/6546">Eclipse Code Formatter
|
||||
Plugin</link> to import the same file.</simpara>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<simpara>Make sure all new <literal>.java</literal> files to have a simple Javadoc class comment with at least an
|
||||
<literal>@author</literal> tag identifying you, and preferably at least a paragraph on what the class is
|
||||
for.</simpara>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<simpara>Add the ASF license header comment to all new <literal>.java</literal> files (copy from existing files
|
||||
in the project)</simpara>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<simpara>Add yourself as an <literal>@author</literal> to the .java files that you modify substantially (more
|
||||
than cosmetic changes).</simpara>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<simpara>Add some Javadocs and, if you change the namespace, some XSD doc elements.</simpara>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<simpara>A few unit tests would help a lot as well — someone has to do it.</simpara>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<simpara>If no-one else is using your branch, please rebase it against the current master (or
|
||||
other target branch in the main project).</simpara>
|
||||
</listitem>
|
||||
<listitem>
|
||||
<simpara>When writing a commit message please follow <link xl:href="http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html">these conventions</link>,
|
||||
if you are fixing an existing issue please add <literal>Fixes gh-XXXX</literal> at the end of the commit
|
||||
message (where XXXX is the issue number).</simpara>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
</section>
|
||||
</appendix>
|
||||
</part>
|
||||
</book>
|
||||
Reference in New Issue
Block a user