[Feat]: Check throwable.cause instance of A2AError in JSONRPCHandler#convertToSendStreamingMessageResponse

[yuyu123-yuyu]

Is your feature request related to a problem? Please describe.

Hello, I ran into the following problem:
I am implementing a customized JSONRPC server, where I use DefaultRequestHandler, JSONRPCHandler from this project, and implemented a customized AgentExecutor.

When I am debuging the SendStreamingMessage method, I throw an UnsupportedOperationError from MyAgentExecutor, but got a -32603 InternalError from the SendStreamingMessageResponse.

It seems that in this function,

a2a-java/transport/jsonrpc/src/main/java/io/a2a/transport/jsonrpc/handler/JSONRPCHandler.java

Line 305 in 7bf82c6

public void onError(Throwable throwable) {

it receives a java.util.concurrent.CompletionException, instead of the UnsupportedOperationError.

Describe the solution you'd like

It seems that the CompletionException has the UnsupportedOperationError as the cause field.

I am wondering if it is reasonable to also check for the cause field of the throwable, to see if it is an instance of the A2AError class. If it is, send the according response.

Something like:

@Override
public void onError(Throwable throwable) {
    if (throwable instanceof A2AError jsonrpcError) {
        tube.send(new SendStreamingMessageResponse(requestId, jsonrpcError));
    } else if (throwable.getCause() != null && throwable.getCause() instanceof A2AError jsonrpcError) { // also check the cause field
        tube.send(new SendStreamingMessageResponse(requestId, jsonrpcError));
    } else {
        tube.send(
                new SendStreamingMessageResponse(
                        requestId, new
                        InternalError(throwable.getMessage())));
    }
    onComplete();
}

It would be helpful if you can take a look. Thanks!

Describe alternatives you've considered

No response

Additional context

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[kabir]

Which version did you use? If you didn't, can you try with the latest 1.0.0.Alpha release? We made some big changes to the underlying event queue mechanisms which may well have touched this.

Note there are some breaking changes to the API, but things should be more stable now going forward.

[yuyu123-yuyu]

Hi, thanks for the reply.

I am currently using version 1.0.0.alpha1.

And I am throwing the UnsupportedOperationError at almost the begining of the MyAgentExecutor#execute(RequestContext, EventQueue). I am not sure when/how the java.util.concurrent.CompletionException is thrown though.

[kabir]

I think I might have fixed this in Alpha2. What I am thinking about is around here https://github.com/a2aproject/a2a-java/blame/main/server-common/src/main/java/io/a2a/server/requesthandlers/DefaultRequestHandler.java#L894-L912

https://quarkus.io/blog/a2a-java-sdk-1-0-0-alpha2-released/ has some descriptions of changes you will have to make to your code to move from Alpha1 to Alpha2

[yuyu123-yuyu]

Noted. I will see if we can switch to Alpha2, and if it fixes this problem.
Thanks!