send data from server with java ee 6 to client

Question

Problem

We have a client-server application, server side is Glassfish 3.1.2. This app has many users, as well as many modules (e.g. View Transactions, View Banks etc). There are some long running processes invoked by client which run on server. Currently we have not found a nice solution to show the user what is going on on the server side. We want the users to get updated messages from server with given frequency. What would you suggest to use?

What we have done/tried

1. We (independently) used an approach with Singleton bean and a Map of client IDs similar to this, and it works of course. But then on the server side every method doSomething(Object... vars) must be converted to doSomething(Object... vars, String clientID) or whatever ID is type of. The client pulls data from server say once per second. I would like to avoid adding facades between server and client.

2. I was thinking about JAX-WS or JAX-RS, but I'm not familiar with these technologies deeply and not sure about what they can do.

3. Sockets

I should note that on the server side we have only Stateless beans (there is a reason for that), that is why I did not mention the use of Stateful bean (which is very good candidate I think).

Regards, Oleg

Answer 1

WebSocket could be a suitable choice, it allows the server to send unsolicited data to clients with no strong coupling, you just have to store a client id to map client connections to running tasks and be able to push updates to the right connection. The client id/socket connection mapping can be maintained in a singleton bean using an in-memory structure, i.e. a hash map, or a permanent datastore for scalability purposes or in case you need a robust solution. Some useful links to better understand WebSocket technology are this and this.