what sort of businees logic is best suited to be processed
by ejb. i mean basically which applications are most suited to ejb.
Where ever u want to make a reusable component u go for EJB.With respect to your requirements we can have our business logics in EJBs (Entity/ Session Beans).We have different design patterns available which can encapsulated the business logic and make it highly reusable.
I wouldn't say whenever you need reusable components go for ejbs..look at what ejb offers you and see if it is needed in your application, e.g., does your application need transaction management, declarative security, to be distributed, to *easily* support clustering, portable, etc.