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NIFI-968 - add @OnPrimaryNodeStateChange to dev guide 

This closes #2027.

Signed-off-by: Andy LoPresto <alopresto@apache.org>
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Pierre Villard 2017-07-21 12:00:18 +02:00 committed by Andy LoPresto
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nifi-docs/src/main/asciidoc/developer-guide.adoc
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@ -564,6 +564,28 @@ while methods using this annotation can be used to clean up resources,
for instance, they should not be for instance, they should not be
relied upon for critical business logic. relied upon for critical business logic.
=== Component Notification
The NiFi API provides notification support through use of Java
Annotations. The `org.apache.nifi.annotations.notification` package
contains several annotations for notification management. The following
annotations may be applied to Java methods in a NiFi component to
indicate to the framework when the methods should be called. For the
discussion of Component Notification, we will define a NiFi component
as a *Processor*, *Controller Service*, or *Reporting Task*.
==== @OnPrimaryNodeStateChange
The `@OnPrimaryNodeStateChange` annotation causes a method to be invoked
as soon as the state of the Primary Node in a cluster has changed.
Methods with this annotation should take either no arguments or one
argument of type `PrimaryNodeState`. The `PrimaryNodeState` provides
context about what changed so that the component can take appropriate
action. The `PrimaryNodeState` enumerator has two possible values:
`ELECTED_PRIMARY_NODE` (the node receiving this
state has been elected the Primary Node of the NiFi cluster), or
`PRIMARY_NODE_REVOKED` (the node receiving this state was the Primary
Node but has now had its Primary Node role revoked).
[[restricted]] [[restricted]]
=== Restricted === Restricted