Error while passing generic Object type to Async.function() as argument

Community Support
6

This only works for Strings and some other simple types that correspond to Json types. As soon as you use a class as an activity argument it is going to break.

For example this doesn’t work:

public class GreetingsArgs {
    private final String greeting;
    private final String name;

    public GreetingsArgs(String greeting, String name) {
      this.greeting = greeting;
      this.name = name;
    }

    public GreetingsArgs() {
      greeting = null;
      name = null;
    }

    public String getGreeting() {
      return greeting;
    }

    public String getName() {
      return name;
    }
  }

  @ActivityInterface
  public interface GreetingActivities {
    String composeGreeting(Object args);
  }

  public class GreetingActivitiesImpl implements GreetingActivities {
    @Override
    public String composeGreeting(Object argsO) {
      GreetingsArgs args = (GreetingsArgs) argsO;
      return args.getGreeting() + " " + args.getName() + "!";
    }
  }

  public class GreetingWorkflowImpl implements GreetingWorkflow {

    private final GreetingActivities activities =
        Workflow.newActivityStub(
            GreetingActivities.class,
            ActivityOptions.newBuilder().setStartToCloseTimeout(Duration.ofSeconds(2)).build());

    @Override
    public String getGreeting(String name) {
      return activities.composeGreeting(new GreetingsArgs("Hello", name));
    }
  }

Here is the failure:

11:44:21.698 [Activity Executor taskQueue="HelloActivityTaskQueue", namespace="default": 1] WARN  i.t.i.sync.POJOActivityTaskHandler - Activity failure. ActivityId=796d71ed-fb6b-33e0-94c2-46529b4ce0d0, activityType=greet, attempt=2
java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to io.temporal.samples.hello.HelloActivity$GreetingsArgs
	at io.temporal.samples.hello.HelloActivity$GreetingActivitiesImpl.composeGreeting(HelloActivity.java:140)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at io.temporal.internal.sync.POJOActivityTaskHandler$POJOActivityInboundCallsInterceptor.execute(POJOActivityTaskHandler.java:297)
	at io.temporal.internal.sync.POJOActivityTaskHandler$POJOActivityImplementation.execute(POJOActivityTaskHandler.java:254)
	at io.temporal.internal.sync.POJOActivityTaskHandler.handle(POJOActivityTaskHandler.java:212)
	at io.temporal.internal.worker.ActivityWorker$TaskHandlerImpl.handle(ActivityWorker.java:192)
	at io.temporal.internal.worker.ActivityWorker$TaskHandlerImpl.handle(ActivityWorker.java:151)
	at io.temporal.internal.worker.PollTaskExecutor.lambda$process$0(PollTaskExecutor.java:73)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)