Is it possible to start a process instance with the key of a process definition and a "processDefinitionVersionTag"?

Hey guys

I’d like to start a particular version (processDefinitionVersionTag) of a process instance via the Start Process Instance | docs.camunda.org API.

For an external task worker to only subscribe to a particular version of a process definition, I use the processDefinitionVersionTag param but this doesn’t seem to work for /process-definition/key/<key>/start as a POST body param.

Any advice?
Thanks

This definitely possible via the Java API (we do this in our project). I’m not sure whether (and how) it’s possible via the REST API. It should be possible since IIUC the REST API is a nearly 100% mirror of the Java API.

Indeed. I’m trying to trace through the source to see how this is done, with no success so far

Why do you want to use the REST API? If you’d create a thin web app you’d be able to use the full power of the Java API.

We can’t use the Java API in our use-case.

Upon further inspection - it seems that the Java API, like the REST API, only allow one to reference a process definition version by its ID.

The example set out in https://docs.camunda.org/manual/7.7/user-guide/process-engine/process-versioning/#which-version-will-be-used shows a demonstration of this, by first looking up the version and then using its ID to start the specific process definition.

Once again, incredible Camunda documentation to the rescue!