Communication between Go and Java workflow

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1

How do I send a signal to a workflow A which was started in Go from a workflow B started in Java?

I tried this:
Workflow.newUntypedExternalWorkflowStub("GO_JAVA_WORK_ID").signal("sigName", true);
but I get an error: called from non workflow or workflow callback thread

This is Go for listening for the channel

var signalVal string
signalChan := workflow.GetSignalChannel(ctx, "sigName")

s := workflow.NewSelector(ctx)
s.AddReceive(signalChan, func(c workflow.ReceiveChannel, more bool) {
	c.Receive(ctx, &signalVal)
	fmt.Println("Received signal", signalVal)
})
s.Select(ctx)
2

Here is a little demo that does this: GitHub - tsurdilo/temporal-polyglot
Where are you creating the newUntypedExternalWorkflowStub and signalling?
Also, the second parameter of your . signal(…) in your Java code from what can tell should be a string type as that is the signal value type you are expecting in your Go workflow.

3

@tihomir I’m creating the newUntypedExternalWorkflowStub in the java activity.

Thanks for making the example. But, I still get the same error called from non workflow or workflow callback thread

"trace": "java.lang.Error: Called from non workflow or workflow callback thread\n\tat io.temporal.internal.sync.DeterministicRunnerImpl.currentThreadInternal(DeterministicRunnerImpl.java:135)\n\tSuppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: \nError has been observed at the following site(s):\n\t|_ checkpoint ⇢ springfox.boot.starter.autoconfigure.SwaggerUiWebFluxConfiguration$CustomWebFilter [DefaultWebFilterChain]\n\t|_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain]\n\t|_ checkpoint ⇢
4

@Abhilash_M Could you share your code or a test that reproduces the issue you are running into so we can take a look? Especially how you are starting the workflow execution would be good to see.

5

Don’t call functions on the Workflow class outside the workflow code. Use WorkflowClient APIs instead. Or better call these APIs from the workflow code without an activity.