I need to implement a TCP server with a web interface included for management.
Basically, the tcp server will be listening to new connections and keeping current ones active while the web interface allow me to see information regarding these connections and to interact with them (e.g. send messages and seeing received ones)...
My concerns resides in the "TCP Server" integration with the web application. For received messages I could simple use a shared DB, but I need to send messages to the peers connected into the TCP server.
My best bet is currently on JCA. Some research pointed me to a nice sample: http://code.google.com/p/jca-sockets. The sample uses an Message Driven Bean to deal with messages received over port 9000, acting as an echo server.
I am new in the Java EE 6 world. I trying to figure out why things were done in one way or another in the sample (e.g. why MDB?).
JCA has a fairly complicated spec. So I am trying at first to adapt the sample above to keep the connections active to exchange data. My next step will be adapt it to accept a string over a servlet to forward it to a given peer.
Can someone help me out on this?
Well, first of all, using Java EE with TCP is not the best approach you may use. If you just need a simple TCP service with Web UI you'd better consider using Java SE with some web container attached (undertow works well).
In other hand, if you need your application to integrate into existing Java EE infrastructure your company has, JCA would be the best approach. While it's not designed for such kind of things, JCA is the only EE subsystem liberal enough for that kind of thread management you would need for TCP networking to work.
JCA-Socket you're referring above is not the best example of a JCA app. It uses plain Java's blocking sockets by blocking WorkManager thread, this is not very effective. Things got much better now and we have Java NIO and Netty for highly effective raw networking to work upon. I have a JCA connector for TCP interactions which may provide you a skeleton to build your own. Feel free to extend and contribute.
P.S. About MDB: message-driven bean is the only "legal" JCA approach of asynchronous incoming messages handling. Since TCP is asynchronous, you'll definitely need one in your application for all the things to start working. Outcoming data transfers happen through various ConnectionFactory interfaces you'll inject into your bean. The link above will provide you with a reference ConnectionFactory implementation as well as a simple tester app utilizing both ConnectionFactory and MDB messaging approaches.