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<title>2. Quick Start</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__a_brief_history_of_springs_data_integration_journey.html" title="1. A Brief History of Spring’s Data Integration Journey"><link rel="next" href="multi__whats_new_in_2_0.html" title="3. What’s New in 2.0?"></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">2. Quick Start</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="multi__a_brief_history_of_springs_data_integration_journey.html">Prev</a> </td><th width="60%" align="center">Part I. Preface</th><td width="20%" align="right"> <a accesskey="n" href="multi__whats_new_in_2_0.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="_quick_start" href="#_quick_start"></a>2. Quick Start</h2></div></div></div><p>You can try Spring Cloud Stream in less then 5 min even before you jump into any details by following this three-step guide.</p><p>We show you how to create a Spring Cloud Stream application that receives messages coming from the messaging middleware of your choice (more on this later) and logs received messages to the console.
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We call it <code class="literal">LoggingConsumer</code>.
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While not very practical, it provides a good introduction to some of the main concepts
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and abstractions, making it easier to digest the rest of this user guide.</p><p>The three steps are as follows:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="xref" href="multi__quick_start.html#spring-cloud-stream-preface-creating-sample-application" title="2.1 Creating a Sample Application by Using Spring Initializr">Section 2.1, “Creating a Sample Application by Using Spring Initializr”</a></li><li class="listitem"><a class="xref" href="multi__quick_start.html#spring-cloud-stream-preface-importing-project" title="2.2 Importing the Project into Your IDE">Section 2.2, “Importing the Project into Your IDE”</a></li><li class="listitem"><a class="xref" href="multi__quick_start.html#spring-cloud-stream-preface-adding-message-handler" title="2.3 Adding a Message Handler, Building, and Running">Section 2.3, “Adding a Message Handler, Building, and Running”</a></li></ol></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-preface-creating-sample-application" href="#spring-cloud-stream-preface-creating-sample-application"></a>2.1 Creating a Sample Application by Using Spring Initializr</h2></div></div></div><p>To get started, visit the <a class="link" href="https://start.spring.io" target="_top">Spring Initializr</a>. From there, you can generate our <code class="literal">LoggingConsumer</code> application. To do so:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">In the <span class="strong"><strong>Dependencies</strong></span> section, start typing <code class="literal">stream</code>.
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When the <span class="quote">“<span class="quote">Cloud Stream</span>”</span> option should appears, select it.</li><li class="listitem">Start typing either 'kafka' or 'rabbit'.</li><li class="listitem"><p class="simpara">Select <span class="quote">“<span class="quote">Kafka</span>”</span> or <span class="quote">“<span class="quote">RabbitMQ</span>”</span>.</p><p class="simpara">Basically, you choose the messaging middleware to which your application binds.
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We recommend using the one you have already installed or feel more comfortable with installing and running.
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Also, as you can see from the Initilaizer screen, there are a few other options you can choose.
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For example, you can choose Gradle as your build tool instead of Maven (the default).</p></li><li class="listitem"><p class="simpara">In the <span class="strong"><strong>Artifact</strong></span> field, type 'logging-consumer'.</p><p class="simpara">The value of the <span class="strong"><strong>Artifact</strong></span> field becomes the application name.
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If you chose RabbitMQ for the middleware, your Spring Initializr should now be as follows:</p></li></ol></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/spring-initializr.png" align="middle" alt="spring initializr"></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p class="simpara">Click the <span class="strong"><strong>Generate Project</strong></span> button.</p><p class="simpara">Doing so downloads the zipped version of the generated project to your hard drive.</p></li><li class="listitem">Unzip the file into the folder you want to use as your project directory.</li></ol></div><div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Tip"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="images/tip.png"></td><th align="left">Tip</th></tr><tr><td align="left" valign="top"><p>We encourage you to explore the many possibilities available in the Spring Initializr.
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It lets you create many different kinds of Spring applications.</p></td></tr></table></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-preface-importing-project" href="#spring-cloud-stream-preface-importing-project"></a>2.2 Importing the Project into Your IDE</h2></div></div></div><p>Now you can import the project into your IDE.
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Keep in mind that, depending on the IDE, you may need to follow a specific import procedure.
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For example, depending on how the project was generated (Maven or Gradle), you may need to follow specific import procedure (for example, in Eclipse or STS, you need to use File → Import → Maven → Existing Maven Project).</p><p>Once imported, the project must have no errors of any kind. Also, <code class="literal">src/main/java</code> should contain <code class="literal">com.example.loggingconsumer.LoggingConsumerApplication</code>.</p><p>Technically, at this point, you can run the application’s main class.
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It is already a valid Spring Boot application.
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However, it does not do anything, so we want to add some code.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="spring-cloud-stream-preface-adding-message-handler" href="#spring-cloud-stream-preface-adding-message-handler"></a>2.3 Adding a Message Handler, Building, and Running</h2></div></div></div><p>Modify the <code class="literal">com.example.loggingconsumer.LoggingConsumerApplication</code> class to look as follows:</p><pre class="programlisting"><em><span class="hl-annotation" style="color: gray">@SpringBootApplication</span></em>
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<em><span class="hl-annotation" style="color: gray">@EnableBinding(Sink.class)</span></em>
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">class</span> LoggingConsumerApplication {
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">static</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">void</span> main(String[] args) {
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SpringApplication.run(LoggingConsumerApplication.<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">class</span>, args);
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}
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<em><span class="hl-annotation" style="color: gray">@StreamListener(Sink.INPUT)</span></em>
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<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 person) {
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System.out.println(<span xmlns:d="http://docbook.org/ns/docbook" class="hl-string">"Received: "</span> + person);
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}
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">static</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">class</span> Person {
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">private</span> String name;
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> String getName() {
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> name;
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}
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<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> setName(String name) {
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">this</span>.name = name;
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}
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">public</span> String toString() {
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<span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">return</span> <span xmlns:d="http://docbook.org/ns/docbook" class="hl-keyword">this</span>.name;
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}
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}
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}</pre><p>As you can see from the preceding listing:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">We have enabled <code class="literal">Sink</code> binding (input-no-output) by using <code class="literal">@EnableBinding(Sink.class)</code>.
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Doing so signals to the framework to initiate binding to the messaging middleware, where it automatically creates the destination (that is, queue, topic, and others) that are bound to the <code class="literal">Sink.INPUT</code> channel.</li><li class="listitem">We have added a <code class="literal">handler</code> method to receive incoming messages of type <code class="literal">Person</code>.
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Doing so lets you see one of the core features of the framework: It tries to automatically convert incoming message payloads to type <code class="literal">Person</code>.</li></ul></div><p>You now have a fully functional Spring Cloud Stream application that does listens for messages.
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From here, for simplicity, we assume you selected RabbitMQ in <a class="link" href="multi__quick_start.html#spring-cloud-stream-preface-creating-sample-application" title="2.1 Creating a Sample Application by Using Spring Initializr">step one</a>.
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Assuming you have RabbitMQ installed and running, you can start the application by running its <code class="literal">main</code> method in your IDE.</p><p>You should see following output:</p><pre class="screen"> --- [ main] c.s.b.r.p.RabbitExchangeQueueProvisioner : declaring queue for inbound: input.anonymous.CbMIwdkJSBO1ZoPDOtHtCg, bound to: input
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--- [ main] o.s.a.r.c.CachingConnectionFactory : Attempting to connect to: [localhost:5672]
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--- [ main] o.s.a.r.c.CachingConnectionFactory : Created new connection: rabbitConnectionFactory#2a3a299:0/SimpleConnection@66c83fc8. . .
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. . .
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--- [ main] o.s.i.a.i.AmqpInboundChannelAdapter : started inbound.input.anonymous.CbMIwdkJSBO1ZoPDOtHtCg
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. . .
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--- [ main] c.e.l.LoggingConsumerApplication : Started LoggingConsumerApplication in 2.531 seconds (JVM running for 2.897)</pre><p>Go to the RabbitMQ management console or any other RabbitMQ client and send a message to <code class="literal">input.anonymous.CbMIwdkJSBO1ZoPDOtHtCg</code>.
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The <code class="literal">anonymous.CbMIwdkJSBO1ZoPDOtHtCg</code> part represents the group name and is generated, so it is bound to be different in your environment.
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For something more predictable, you can use an explicit group name by setting <code class="literal">spring.cloud.stream.bindings.input.group=hello</code> (or whatever name you like).</p><p>The contents of the message should be a JSON representation of the <code class="literal">Person</code> class, as follows:</p><pre class="literallayout">{"name":"Sam Spade"}</pre><p>Then, in your console, you should see:</p><p><code class="literal">Received: Sam Spade</code></p><p>You can also build and package your application into a boot jar (by using <code class="literal">./mvnw clean install</code>) and run the built JAR by using the <code class="literal">java -jar</code> command.</p><p>Now you have a working (albeit very basic) Spring Cloud Stream application.</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="multi__a_brief_history_of_springs_data_integration_journey.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__whats_new_in_2_0.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">1. A Brief History of Spring’s Data Integration Journey </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"> 3. What’s New in 2.0?</td></tr></table></div></body></html> |