Distributing Swing Application

[Sri Rangan]

We have written a Stand alone swing application with Hypersonic as the database.
Now we would like to distribute this swing app. The process is as below:
1) Post the swing exe or jar in a website.
2) User down loads and install the application.
( We could use Java Web start) for down loading the latest jar/exe.
The area we are not very clear is " How to communicate and do transaction from the client installation to the server."
I guess we could RMI or webservices. But I am looking for DETAILED information about the possibilities how this could be achieved.
Unfortunately, this app has got too much of business logic and complicated screens to decide go a struts bases web site.