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I have a stream comprising of

Source | ProcessorP1 | ProcessorP2 | ProcessorP3 | ProcessorP4 | Sink

I'm using ProcessorP1 as my tasklaunchrequest-transform processor. I'm using this to launch a task via task-launcher. Now I need to pass on my payload from ProcessorP1 to ProcessorP2 and also invoke the task; The TaskLaunchRequest has no way to carry the payload as it is ignored.

https://github.com/spring-cloud-stream-app-starters/tasklaunchrequest-transform/blob/master/spring-cloud-starter-stream-processor-tasklaunchrequest-transform/README.adoc

Is there a way to pass on the payload to next processor in my stream?

Kanika Sharma
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  • Could you clarify about what you mean by the `payload` from `Processor1`. The `payload` is going to be your `TaskLaunchRequest` which will be carried to the `task-launcher`. `tasklaunchrequest-transform` ignores any incoming payload and headers. – sobychacko Oct 11 '17 at 19:58
  • The `ProcessorP1` takes input from `Source`, it then discards it and creates a new `TaskLaunchRequest` which it sends on its output channel. This is then consumed by the `task-launcher` attached at the tap and is also consumed by `ProcessorP2`. I wanted to know if there is a way to **NOT** ignore the incoming payload from `Source` and be able to pass that on to `ProcessorP2`, or include that incoming payload in the `TaskLaunchRequest` itself. – Kanika Sharma Oct 11 '17 at 21:12

1 Answers1

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Since the tasklaunchrequest-transform-processor ignores the incoming payload, in order to accomplish what you are looking for, you need to customize the processor, i.e, you have to change the logic in the processor so that it takes the incoming payload and attaches to the TaskLaunchRequest somehow. If the incoming payload is a String type, you can then add that as a environment property or a command line arg in the TaskLaunchRequest - then essentially pass this modified request down through the stream. Basically, you need to replace your ProcessorP1 with a custom takslaunchrequest-transform-processor that does this.

See here for some guidelines for patching the out of the box applications: https://docs.spring.io/spring-cloud-stream-app-starters/docs/current/reference/htmlsingle/#_patching_pre_built_applications or creating new ones: https://docs.spring.io/spring-cloud-stream-app-starters/docs/current/reference/htmlsingle/#_creating_new_stream_application_starters_and_generating_artifacts

sobychacko
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  • Thanks @sobychacko. I'll look at the posted links. – Kanika Sharma Oct 12 '17 at 15:27
  • There's a relevant issue on this matter (https://github.com/spring-cloud-stream-app-starters/app-starters-release/issues/46). Feel free to share your findings and other ideas on how you've solved it. – Sabby Anandan Oct 25 '17 at 17:57