EJB ARCHITECTURE
The Enterprise JavaBeans spec defines a server component model and specifies, how to
create server-side, scalable, transactional, multiuser and secure enterprise-level components. Most
important, EJBs can be deployed on top of existing transactioncreate server-side, scalable, transactional, multiuser and secure enterprise-level components. Most
processing systems including traditional transaction processing monitors, Web, database
and application servers.
A typical EJB architecture consists of:
• EJB clients: EJB client applications utilise the Java Naming and Directory Interface
(JNDI) to look up references to home interfaces and use home and remote EJB
interfaces to utilise all EJB-based functionality.
(JNDI) to look up references to home interfaces and use home and remote EJB
interfaces to utilise all EJB-based functionality.
• EJB home interfaces (and stubs): EJB home interfaces provide operations for
clients to create, remove, and find handles to EJB remote interface objects.
Underlying stubs marshal home interface requests and unmarshal home interface
responses for the client.
clients to create, remove, and find handles to EJB remote interface objects.
Underlying stubs marshal home interface requests and unmarshal home interface
responses for the client.
• EJB remote interfaces (and stubs): EJB remote interfaces provide business-specific
client interface methods defined for a particular EJB. Underlying stubs marshal
remote interface requests and unmarshal remote interface responses for the client.
client interface methods defined for a particular EJB. Underlying stubs marshal
remote interface requests and unmarshal remote interface responses for the client.
• EJB implementations: EJB implementations are the actual EJB application
components implemented by developers to provide any application-specific business
method invocation, creation, removal, finding, activation, passivation, database
storage, and database loading logic.
components implemented by developers to provide any application-specific business
method invocation, creation, removal, finding, activation, passivation, database
storage, and database loading logic.
• Container EJB implementations (skeletons and delegates): The container manages
the distributed communication skeletons used to marshal and unmarshal data sent to
and from the client. Containers may also store EJB implementation instances in a pool
and use delegates to perform any service-management operations related to a
particular EJB before calls are delegated to the EJB implementation instance.
Some of the advantages of pursuing an EJB solution are:
the distributed communication skeletons used to marshal and unmarshal data sent to
and from the client. Containers may also store EJB implementation instances in a pool
and use delegates to perform any service-management operations related to a
particular EJB before calls are delegated to the EJB implementation instance.
Some of the advantages of pursuing an EJB solution are:
• EJB gives developers architectural independence.
• EJB is WORA for server-side components.
• EJB establishes roles for application development.
• EJB takes care of transaction management.
• EJB provides distributed transaction support.
• EJB helps create portable and scalable solutions.
• EJB integrates seamlessly with CORBA.
• EJB provides for vendor-specific enhancements.
• EJB is WORA for server-side components.
• EJB establishes roles for application development.
• EJB takes care of transaction management.
• EJB provides distributed transaction support.
• EJB helps create portable and scalable solutions.
• EJB integrates seamlessly with CORBA.
• EJB provides for vendor-specific enhancements.
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