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GH-1928: Roles: Doc Polishing

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Fixes #1928 https://github.com/spring-projects/spring-integration/issues/1928
This commit is contained in:
Gary Russell
2016-10-12 11:21:11 -04:00
committed by Artem Bilan
parent 890ad63584
commit 7c12288d2e
1 changed files with 9 additions and 3 deletions
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12
src/reference/asciidoc/endpoint.adoc
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@@ -584,7 +584,8 @@ You can assign endpoints to roles using XML, Java configuration, or programmatic
[source, xml]
----
<int:inbound-channel-adapter id="ica" channel="someChannel" expression="'foo'" role="cluster">
<int:inbound-channel-adapter id="ica" channel="someChannel" expression="'foo'" role="cluster"
auto-startup="false">
<int:poller fixed-rate="60000" />
</int:inbound-channel-adapter>
----
@@ -592,7 +593,7 @@ You can assign endpoints to roles using XML, Java configuration, or programmatic
[source, java]
----
@Bean
@ServiceActivator(inputChannel = "sendAsyncChannel")
@ServiceActivator(inputChannel = "sendAsyncChannel", autoStartup="false")
@Role("cluster")
public MessageHandler sendAsyncHandler() {
return // some MessageHandler
@@ -630,6 +631,8 @@ The `SmartLifecycleRoleController` implements `ApplicationListener<AbstractLeade
start/stop its configured `SmartLifecycle` objects when leadership is granted/revoked (when some bean publishes
`OnGrantedEvent` or `OnRevokedEvent` respectively).
IMPORTANT: When using leadership election to start/stop components, it is important to set the `auto-startup` XML attribute (`autoStartup` bean property) to `false` so the application context does not start the components during context intialization.
[[leadership-event-handling]]
=== Leadership Event Handling
@@ -638,7 +641,10 @@ This is useful in clustered scenarios where shared resources must only be consum
An example of this is a file inbound channel adapter that is polling a shared directory.
(See <<file-reading>>).
To participate in a leader election and be notified when elected leader or when leadership is revoked, an application creates a component in the application context called a "leader initiator". Normally a leader initiator is a `SmartLifecycle` so it starts up (optionally) automatically when the context starts, and then publishes notifications when leadership changes. By convention the user provides a `Candidate` that receives the callbacks and also can revoke the leadership through a `Context` object provided by the framework. User code can also listen for `AbstractLeaderEvents`, and respond accordingly, for instance using a `SmartLifecycleRoleController`.
To participate in a leader election and be notified when elected leader or when leadership is revoked, an application creates a component in the application context called a "leader initiator".
Normally a leader initiator is a `SmartLifecycle` so it starts up (optionally) automatically when the context starts, and then publishes notifications when leadership changes.
By convention the user provides a `Candidate` that receives the callbacks and also can revoke the leadership through a `Context` object provided by the framework.
User code can also listen for `AbstractLeaderEvents`, and respond accordingly, for instance using a `SmartLifecycleRoleController`.
There is a basic implementation of a leader initiator based on the `LockRegistry` abstraction. To use it you just need to create an instance as a bean, for example: