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Code switcher in the channel-adapter.adoc

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Artem Bilan
2021-05-10 16:51:18 -04:00
parent 49f0398144
commit d00a3b9a2e
1 changed files with 106 additions and 9 deletions
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115
src/reference/asciidoc/channel-adapter.adoc
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@@ -11,14 +11,63 @@ These provide an easy way to extend Spring Integration, as long as you have a me
[[channel-adapter-namespace-inbound]]
==== Configuring An Inbound Channel Adapter
An `inbound-channel-adapter` element can invoke any method on a Spring-managed object and send a non-null return value to a `MessageChannel` after converting the method's output to a `Message`.
An `inbound-channel-adapter` element (a `SourcePollingChannelAdapter` in Java configuration) can invoke any method on a Spring-managed object and send a non-null return value to a `MessageChannel` after converting the method's output to a `Message`.
When the adapter's subscription is activated, a poller tries to receive messages from the source.
The poller is scheduled with the `TaskScheduler` according to the provided configuration.
To configure the polling interval or cron expression for an individual channel adapter, you can provide a 'poller' element with one of the scheduling attributes, such as 'fixed-rate' or 'cron'.
The following example defines two `inbound-channel-adapter` instances:
====
[source,xml]
[source, java, role="primary"]
.Java DSL
----
@Bean
public IntegrationFlow source1() {
return IntegrationFlows.from(() -> new GenericMessage<>(...),
e -> e.poller(p -> p.fixedRate(5000)))
...
.get();
}
@Bean
public IntegrationFlow source2() {
return IntegrationFlows.from(() -> new GenericMessage<>(...),
e -> e.poller(p -> p.cron("30 * 9-17 * * MON-FRI")))
...
.get();
}
----
[source, java, role="secondary"]
.Java
----
public class SourceService {
@InboundChannelAdapter(channel = "channel1", poller = @Poller(fixedRate = "5000"))
Object method1() {
...
}
@InboundChannelAdapter(channel = "channel2", poller = @Poller(cron = "30 * 9-17 * * MON-FRI"))
Object method2() {
...
}
}
----
====
[source, kotlin, role="secondary"]
.Kotlin DSL
----
@Bean
fun messageSourceFlow() =
integrationFlow( { GenericMessage<>(...) },
{ poller { it.fixedRate(5000) } }) {
...
}
----
====
----
[source, xml, role="secondary"]
.XML
----
<int:inbound-channel-adapter ref="source1" method="method1" channel="channel1">
<int:poller fixed-rate="5000"/>
@@ -38,7 +87,7 @@ See <<./endpoint.adoc#endpoint-namespace,Endpoint Namespace Support>> for more d
[IMPORTANT]
.Important: Poller Configuration
=====
Some `inbound-channel-adapter` types are backed by a `SourcePollingChannelAdapter`, which means they contain a poller configuration that polls the `MessageSource` (to invoke a custom method that produces the value that becomes a `Message` payload) based on the configuration specified in the Poller.
All the `inbound-channel-adapter` types are backed by a `SourcePollingChannelAdapter`, which means they contain a poller configuration that polls the `MessageSource` (to invoke a custom method that produces the value that becomes a `Message` payload) based on the configuration specified in the Poller.
The following example shows the configuration of two pollers:
====
@@ -83,11 +132,45 @@ Starting with version 5.5, a `0` value for `max-messages-per-poll` has a special
[[channel-adapter-namespace-outbound]]
==== Configuring An Outbound Channel Adapter
An `outbound-channel-adapter` element can also connect a `MessageChannel` to any POJO consumer method that should be invoked with the payload of messages sent to that channel.
An `outbound-channel-adapter` element (a `@ServiceActivator` for Java configuration) can also connect a `MessageChannel` to any POJO consumer method that should be invoked with the payload of messages sent to that channel.
The following example shows how to define an outbound channel adapter:
====
[source,xml]
[source, java, role="primary"]
.Java DSL
----
@Bean
public IntegrationFlow outboundChannelAdapterFlow(MyPojo myPojo) {
return f -> f
.handle(myPojo, "handle");
}
----
[source, java, role="secondary"]
.Java
----
public class MyPojo {
@ServiceActivator(channel = "channel1")
void handle(Object payload) {
...
}
}
----
====
[source, kotlin, role="secondary"]
.Kotlin DSL
----
@Bean
fun outboundChannelAdapterFlow(myPojo: MyPojo) =
integrationFlow {
handle(myPojo, "handle")
}
----
====
----
[source, xml, role="secondary"]
.XML
----
<int:outbound-channel-adapter channel="channel1" ref="target" method="handle"/>
@@ -95,10 +178,24 @@ The following example shows how to define an outbound channel adapter:
----
====
If the channel being adapted is a `PollableChannel`, you must provide a poller sub-element, as the following example shows:
If the channel being adapted is a `PollableChannel`, you must provide a poller sub-element (the `@Poller` sub-annotation on the `@ServiceActivator`), as the following example shows:
====
[source,xml]
----
[source, java, role="primary"]
.Java
----
public class MyPojo {
@ServiceActivator(channel = "channel1", poller = @Poller(fixedRate = "3000"))
void handle(Object payload) {
...
}
}
----
[source, xml, role="secondary"]
.XML
----
<int:outbound-channel-adapter channel="channel2" ref="target" method="handle">
<int:poller fixed-rate="3000" />
@@ -152,6 +249,6 @@ See also the `cacheSeconds` property on the `ReloadableResourceBundleExpressionS
For more information regarding expressions, see <<./spel.adoc#spel,Spring Expression Language (SpEL)>>.
For scripts, see <<./groovy.adoc#groovy,Groovy support>> and <<./scripting.adoc#scripting,Scripting Support>>.
IMPORTANT: The `<int:inbound-channel-adapter/>` is endpoint starts a message flow by periodically triggering to poll some underlying `MessageSource`.
IMPORTANT: The `<int:inbound-channel-adapter/>` (`SourcePollingChannelAdapter`) is an endpoint which starts a message flow by periodically triggering to poll some underlying `MessageSource`.
Since, at the time of polling, there is no message object, expressions and scripts do not have access to a root `Message`, so there are no payload or headers properties that are available in most other messaging SpEL expressions.
The script can generate and return a complete `Message` object with headers and payload or only a payload, which is added to a message with basic headers.
The script can generate and return a complete `Message` object with headers and payload or only a payload, which is added to a message with basic headers by the framework.