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https://issues.apache.org/jira/browse/YARN-1564?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13862988#comment-13862988
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Steve Loughran commented on YARN-1564:
--------------------------------------
Services are all in
[[https://github.com/hortonworks/hoya/tree/develop/hoya-core/src/main/java/org/apache/hadoop/hoya/yarn/service]]
*
[[Parent|https://github.com/hortonworks/hoya/blob/develop/hoya-core/src/main/java/org/apache/hadoop/hoya/yarn/service/Parent.java]]:
interface that makes {{addService}} public and adds an option to list
services. This could be retrofitted to {{CompositeService}}
*
[[CompoundService|https://github.com/hortonworks/hoya/blob/develop/hoya-core/src/main/java/org/apache/hadoop/hoya/yarn/service/CompoundService.java]
: subclass of {{CompositeService}} that finishes when all of its children have
*successfully* completed, or when any of its children fail.
*
[[SequenceService|https://github.com/hortonworks/hoya/blob/develop/hoya-core/src/main/java/org/apache/hadoop/hoya/yarn/service/SequenceService.java]]
subclass of {{CompositeService}} that executes its children in sequence,
starting one when the previous one successfully finishes. Again, failures are
propagated up immediately.
*
[[EventNotifyingService|https://github.com/hortonworks/hoya/blob/develop/hoya-core/src/main/java/org/apache/hadoop/hoya/yarn/service/EventNotifyingService.java]]
service which triggers a callback to a supplied interface implementation when
started -or after a specified delay from the start time.
**
[[ForkedProcessService.java|https://github.com/hortonworks/hoya/blob/develop/hoya-core/src/main/java/org/apache/hadoop/hoya/yarn/service/ForkedProcessService.java]]:
more complex, this forks a potentially long lived application (via
[[RunLongLivedApp|https://github.com/hortonworks/hoya/blob/develop/hoya-core/src/main/java/org/apache/hadoop/hoya/exec/RunLongLivedApp.java]]),
completing the service when that process finishes.
The set allows you build up sequences of operations, as well as actions to run
in parallel, and to notify a parent service or other object when they complete
or fail.
There's tests for the simple ones (Sequence, compound, events) in groovy;
nothing yet for forked processes.
> add some basic workflow YARN services
> -------------------------------------
>
> Key: YARN-1564
> URL: https://issues.apache.org/jira/browse/YARN-1564
> Project: Hadoop YARN
> Issue Type: New Feature
> Components: api
> Affects Versions: 2.2.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Minor
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> I've been using some alternative composite services to help build workflows
> of process execution in a YARN AM.
> They and their tests could be moved in YARN for the use by others -this would
> make it easier to build aggregate services in an AM
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