Workflow lifecycle hooks

[danphilibin]

I'm building something on top of Workflow and it would be helpful to have lifecycle hooks for events like "workflow started", "workflow completed", "workflow paused", etc. A practical example is triggering a workflow from a web UI and getting visual confirmation when the workflow is completed, without every workflow having to implement a completion signal at the end.

Ideally these would be callback functions (or steps?) that can access some basic data about the workflow and make network requests.

Any plans to bring something like this to Workflow?

[pranaygp]

For now, the easiest thing to do is to just keep polling the run.status property. each time you await it, it gets the latest value. infact, that's how run.returnValue currently works - it just polls the status till a value is ready

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Long term:

I would love this. We've intentionally reserved the namepsacing in streams so that we could do "system" streams for each run where we automatically emit these lifecycle events

that way, the Run object could return a run.getReadable({system: true}) (probably better API naming though), and we can emit lifecycle events there. Then run.returnValue would just use the stream instead of polling. And we can support more higher lever helpers in run like run.waitUntil({status: "started"}) etc. all on top of the stream

[pranaygp]

If you'd like to help take a stab at implementing it, please do open a PR. We simply might not be able to get around to it ourselves as a core team anytime soon

[danphilibin]

Appreciate the context, may take a swing at it!