Session beans may be stateless, allowing the EJB server to reuse instances of the
bean to service clients, or stateful (i.e., bound to clients directly). Database cache
information maintained by stateful session beans is synchronized with the database
when transactions occur by using JDBC or SQLJ. Entity Java beans, also known as
persistent beans (because they remain in existence through multiple sessions), were
not supported in Oracle8i but are supported in Oracle9i and subsequent database
JVMs. The third type of EJB is the message-driven bean, designed to receive asynchronous
Java Message Services (JMS) messages and supported via Oracle??™s more
recent Applications Servers that support EJB 3.0.
324 | Chapter 14: Oracle Extended Datatypes
Extensibility Features and Options
Oracle??™s extensibility features and options extend SQL to perform tasks that can??™t
otherwise be easily programmed in a relational database. These include manipulation
of text, multimedia and content, and spatial data. These features are typically
used by application developers but are sometimes bundled with applications sold by
Oracle partners.
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