How to send a Signal from a Workflow in Java

To send a Signal from within a Workflow to a different Workflow Execution, initiate an ExternalWorkflowStub in the implementation of the current Workflow and call the Signal method defined in the other Workflow.

The following example shows how to use an untyped ExternalWorkflowStub in the Workflow implementation to send a Signal to another Workflow.

    public String sendGreeting(String name) {

        // initiate ExternalWorkflowStub to call another Workflow by its Id "ReplyWF"
        ExternalWorkflowStub callRespondWorkflow = Workflow.newUntypedExternalWorkflowStub("ReplyWF");

        String responseTrigger = activity.greeting("Hello", name);

        // send a Signal from this sendGreeting Workflow to the other Workflow
        // by calling the Signal method name "getGreetCall" defined in that Workflow.
        callRespondWorkflow.signal("getGreetCall", responseTrigger);

        return responseTrigger;