Build a server for client/server side bidirectional communication feedback system in Java?

Scenario: User logs in on the client software which forms a persistent bidirectional connection with the serverside entity (server) which would process user specified tasks. When the serverside entity, while processing user's task, encounters an error or requires further user input, it will notify the client software, and wait until the client decides what to do. The client software will take the new user specifiefd inputs and send this to the serverside. The serverside continue where it last stopped with the new user specified inputs. This feedback cycle will continue until it's finished processing. The progressively updated user inputs will all be stored on the serverside and accessible and modifiable from the client software. So if a client deletes a specific input, that change will be immediately reflected on the serverside. On the serverside, an extra interface is probably required to route different user's clients to available hardware nodes (cloud) to support concurrent multi-user 开发者_高级运维tasks running on the serverside.

On the client side, I suspect using sockets to connect to the server...

Now for the server, I am a little lost because there seems to be many different Java servers like Jetty & Netty. I am also practicing caution in order to not try and reinvent any wheels here.

Is building a server the right approach? or Build a webservice that will complete a specific task on demand?

I am also not just looking for a one size fits all solution (wishful thinking probably) but open to any insights on my current situation.

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Netty will provide a lot of what it sounds like you need for this, without making you reinvent a socket server. That said, I would make certain that you actually need bidirectional, real-time communication between the client and server. If you can rework the problem such that the client-server communications do not need to be real-time, then things like RESTful webservices become a possibility, and (in my experience) are much less complicated and error prone.