I currently have a web application and I would like to add a messaging feature to it. In order to do that, I use JMS(actually OpenMQ, the implementation provided with Glassfish 3). The problem is that I do not know how to get the message notification from the background(from the listener) to the foreground. I am using JSF as a framework, if it does have an importance. Could you please tell me how should I notify the user about a received message(like a chat). Any suggestions are welcomed(tutorials, advices or libraries, but all these should be free).
You may be interested in Comet, a programming model that allows the server to push data to a client. There are implementations for JSF, look at this blog post about Richfaces integration for an example.
HTML 5 specifies WebSockets that can be used for server push, but not all browsers support it.
The simple alternative is to simply poll the server at regular intervals, that might create a lot of unnecessary messages though.