Poll2Push Converter and example with Openwhisk

The flow inserts a subflow named Poll2PushConverter, in order to simplify the process of polling towards an endpoint that does not support blocking calls up to completion. The initial call returns after a specified period and is then fed to the Poll2PushConverter in order to undertake the polling. Upon successful completion (or reaching of max number of attempts), the subflow triggers a message to one of the respective outputs.

An example flow is also included with relation to how to apply it to an Openwhisk web action invocation that defaults to 65 seconds of waiting time in the initial blocking call, while the action takes longer to complete.

The docker image of the used action can be found here and is a delay action that takes as inputs the iterations and the delay of each iteration: https://hub.docker.com/r/gkousiou/noderedaction

the flow for which can be found here https://flows.nodered.org/flow/f0795ad9f25ad2affcadb8deb305fdf3/in/VOf-0UrN5e2j

In the flow it is assumed that it has been registered with the following options: wsk action create dockeraction --docker gkousiou/noderedaction --web true

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