[jira] [Resolved] (NIFI-190) Wait/Notify processors

["Bryan Bende (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/NIFI-190?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bryan Bende resolved NIFI-190.
------------------------------
    Resolution: Fixed

Merged to master.

> Wait/Notify processors
> ----------------------
>
>                 Key: NIFI-190
>                 URL: https://issues.apache.org/jira/browse/NIFI-190
>             Project: Apache NiFi
>          Issue Type: New Feature
>          Components: Extensions
>            Reporter: Joseph Gresock
>            Assignee: Joseph Gresock
>            Priority: Minor
>             Fix For: 1.2.0
>
>         Attachments: Wait_Notify_template.xml
>
>
> Our team has developed a set of processors for the following use case:
> * Format A needs to be sent to Endpoint A
> * Format B needs to be sent to Endpoint B, but should not proceed until A has reached Endpoint A.  We most commonly have this restriction when Endpoint B requires some output of Endpoint A.
> The proposed Wait/Notify processors enable this functionality:
> * Wait: routes files to the 'wait' relationship until a matching Release Signal Identifier is found in the distributed map cache.  Then routes them to 'success' (unless they have expired)
> * Notify: stores a Release Signal Identifier in the distributed map cache, optionally with attributes to copy to the outgoing matching Wait flow files.
> An example:
> Wait is configured with Release Signal Attribute = "$\{myId}". Its 'wait' relationship routes back onto itself.
>     flowFile 1 \{ myId : "123" }
>     comes into Wait processor
>     Wait checks the distributed cache map for "123", doesn't find it, and is routed to the 'wait' relationship
> Notify is configured with Release Signal Attribute = "$\{myId}"
>     flowFile 2 \{ myId : "123" }
>     comes in to Notify processor
>     Notify puts an entry in the map for "123" with any other attributes from flowFile2
> Next time flowFile 1 is processed by Wait...
>     Finds an entry for "123"
>     Removes that entry from the map
>     Copies attributes to flowFile 1
>     Sends flowFile 1 out the success relationship
> Notify will optionally cache attributes in the distributed map, as determined by a regex property.  This is what allows the output of Endpoint A to pass to Endpoint B, above.  Wait also allows conflicting attributes from the cache to either be replaced or kept, depending on property configuration.



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