How to make my Java Swing application a Client-Server application?

Question

I have made a Java Swing application. Now I would like to make it a Client-Server application. All clients should be notified when data on the server is changed, so I'm not looking for a Web Service. The Client-Server application will be run on a single LAN, it's a business application. The Server will contain a database, JavaDB.

What technology and library is easiest to start with? Should I implement it from scratch using Sockets, or should I use Java RMI, or maybe JMS? Or are there other alternatives that are easier to start with?

And is there any server library that I should use? Is Jetty an alternative?

Answer 1

Given that you have the application already, perhaps the simplest thing to do is to identify the interface that you require between the client and server, and first of all to refactor your application to use that interface to talk between the back-end/front-end within the same process.

Then you can start to split this apart. A simple solution would be to split this apart using RMI (since you're talking Java objects and have Java method calls). Spring contains useful tools to simplify/automate the RMI exposure of interfaces.

For the notification requirement, a simple UDP multicast (or broadcast) would suffice.

Note that as soon as you split your application up, you have issues re. maintaining consistent views of data, managing timely updates, handling cases when the server is down, possible loading issues when you get lots of clients etc. In a sense, splitting the application up into a client and server is just the start of a new architecture process.

Answer 2

Mina is a good choice as a network application framework for building a simple server for this purpose - it's a much better option than using raw sockets.

http://mina.apache.org/

If you really need an application server then you could take look at JBoss. It also provides a remoting component (as an alternative to something like Mina):

http://www.jboss.org/jbossremoting

You probably won't have much need for Enterprise Java Beans though. In most cases a simple POJO based framework is more than sufficient - you could tie this altogether with a dependency injection framework such as Guice:

http://code.google.com/p/google-guice/

or Spring. Keep it simple, don't use a J2EE server unless you really need to. Hope that helps.