The obvious solution is probably the best: Use an asynchronous framework (like node.js or asyncio) for the REST interface and wait for the completion of the tas

The obvious solution is probably the best: Use an asynchronous framework (like node.js or asyncio) for the REST interface and wait for the completion of the task to return a response. That process wouldn't handle all the details of the task, but it can wait for notification of the task via other means (celery, rabbitmq, redis, whatever...). Personally I think REST is the best paradigm for most microservices. There is one exception: Data streams are inherently stateful and some kind of websocket/message passing is a lot more useful in that case.