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https://issues.apache.org/jira/browse/NIFI-190?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14701420#comment-14701420
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Bryan Bende commented on NIFI-190:
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Controlling the signaling based on node vs cluster is an interesting idea. I'm
wondering if this can already be achieved by the current design if we just use
DistributedMapCacheClient...
- The Wait processor would have a property on it that provides the name of a
FlowFile attribute that holds the "release signal" (key) for the given
FlowFile, this attribute value is what it would use to check the map and say
"do I have a signal for this key yet?"
- The Notify processor would have a similar property that tells it what
FlowFile attribute to use as the "release value", this vlaue would be the key
used to put a signal into the Map
Each Wait processor can be waiting for different signals, so it would really be
up to the processors sitting before these processors to determine how the
keys/signals will be managed right?
> HoldFile processor
> ------------------
>
> 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: Bryan Bende
> Priority: Minor
> Attachments: HoldFile_example.xml
>
>
> Our team has developed a processor 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 HoldFile processor takes 2 types of flow files as input:
> * Files to be held
> * Signal files that can release corresponding held files, based on the value
> of a configurable "release" attribute
> Signal files are distinguished from held files by the presence of the
> "flow.file.release.value" attribute. The processor is configured with a
> "Release Signal Attribute". Held files with this attribute whose value
> matches a received signal value will be released.
> An example:
> HoldFile is configured with Release Signal Attribute = "myId". Its 'Hold'
> relationship routes back onto itself.
> 1. flowFile 1 { myId : "123" } enters HoldFile. It is routed to the 'Hold'
> relationship
> 2. flowFile 2 { flow.file.release.value : "123" } enters HoldFile. flowfile
> 1 is then routed to 'Release', and flow file 2 is removed from the session.
> Signal flow files will also copy their attributes to matching held files,
> unless otherwise indicated. This is what allows the output of Endpoint A to
> pass to Endpoint B, above.
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