Hi, As for DCT development you can use the FormAPI callServer method to call into a custom Java Servlet which then can return JavaScript that will call the FromAPI to change the DCT. At least that is the design pattern that my team has used. Just remember that it's asynchronous and you need to use a callback pattern. Using that pattern you don't have to keep making new CSClient sessions.FYI: Spring and Hibernate work well with custom servlets and help to keep adherence to MVC.
Gopi,If You are familiar with Java then go through the cssdk_doc.This doc will help you a lot.Yes,You can call java classes for various purposes e.g,.You can call it in a workflow to achieve your desired result through url external task.Rest upon your requirement.HTH.Thanks,Santosh.