If you want to write your application for Symbian 7.0s than you can easily use HTTP connection to communicate with a remote machine running for example Tomcat or some other server.
To be able to do that you should derive your own class from MHTTPTransactionCallback abstract class and you should implement these functions:
Other classes you must use are: RHTTPSession and RHTTPTransaction (there are other classes too).
virtual void MHFRunL(RHTTPTransaction aTransaction, const THTTPEvent& aEvent);
virtual TInt MHFRunError(TInt aError, RHTTPTransaction aTransaction, const THTTPEvent& aEvent);
There is an example that comes with Series 60 SDK and it is located in: Examples\appprots\exampleclient directory so you can start with it.
I hope this will help you.