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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
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