Even for organizations that aren't concerned about diverse environments, the EJB architecture and programming model can be used as a standard for server software development across different units. This article provides a brief overview of the past, present and future of Enterprise JavaBeans. It also briefly describes an example EJB environment and its development tools. For space reasons we'll refrain from presenting any background information on transactions, security, persistence or various other distributed object concepts. The former model business entities, such as a customer, an invoice or a contract.
Entity beans are persistent, that is, they're stored in a database.
This scheme limits the beans' possible property types to a relative few, however, because the container accesses the properties directly when a bean is stored and restored. The only thing that can be assumed across various containers is that their persistence mechanisms support the basic Java types. With the bean-managed scheme the container doesn't access a bean's properties directly. The entity bean itself knows how to store and restore its state. Therefore the EJBs' internal composition structure can be whatever the developer desires and the container doesn't limit the property types.