temporalio / temporalio/temporal

Add ability for workflow to wait for completion of an external workflow

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API devexp enhancement up-for-grabs
Dominant language
Go
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Avg merge
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Merged PRs (30d)
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Description

Currently, the workflow code can wait for the completion of its child workflow.
It is also possible to wait for the completion of any workflow given its id from an external client.
Ability waiting for the completion of any workflow from a decider code is missing.

Strawman proposal:

Add a WaitForExternalWorkflowCompletion decision and the corresponding event.
Add a WaitForExternalWorkflowCompletionFailed event
Add ExternalWorkflowCompleted/Failed/Cancelled/Terminated/TimedOut events. Another option is to have an
ExternalWorkflowCompleted event that contains the termination event of the external workflow as a field.

Copied from https://github.com/uber/cadence/issues/656

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Research direction

Start by tracing how decider code waits for child workflow completion and how an external client waits by workflow ID. Compare those paths to define the decision and event handling needed for external workflow completion, including failure, cancellation, termination, and timeout. Done means a decider can wait on any external workflow and receive the corresponding completion outcome.

Written by the indexing model from the issue text.

Assessment

Tech stack
go
Domain
distributed-systems
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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