"The J2EE programming model divides responsibilities between Application Component Providers and J2EE Product Providers: Application Component Providers focus on writing business logic and the J2EE Product Providers focus on providing a managed system infrastructure in which the application components can be deployed.
This division leads to a restriction on the functionality that application components can contain. If application components contain the same functionality provided by J2EE system infrastructure, there are clashes and mis-management of the functionality. "