You want to build applications that last. You want to build them
fast, and you want to leverage your existing databases, applications,
systems, infrastructure . . . management.
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Develop business components with Enterprise
JavaBeans
- Enterprise JavaBeans provide a component model that will help you
meet these goals. WebLogic EJB provides entity and session beans, which
means WebLogic Server automates database components (entities), as well as
classic transaction model components (sessions).
WebLogic EJB offers you:
- Automatic persistence (database and file access)
- Automatic, declarative transaction models
- Client authentication and access control at the method level
- Resource management for threads, network, and database connections
- Bean caching
- Bean life-cycle management for creating, finding, and destroying
beans
- Concurrency control
- External configuration of bean runtime properties
- Dynamic deployment of beans in a running server
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Support all clients -- web, mobile, intranet, LAN --
with the same business components
- WebLogic Server supports multiple programming models: web- and
intranet-based HTML clients, browser-based applets, intranet- and
LAN-based desktop clients, as well as legacy environments, such as
COM/ActiveX and CORBA. You can isolate business logic inside EJB
components, and use the same beans for all these clients!
Standard Java Servlets, which can be completely generated using
Java Server Pages (JSP) can isolate the presentation logic from
the EJB business logic for the HTML client. Desktop applications
written in Java or Visual Basic using Visual Cafeacute;, Visual Age,
PowerBuilder and other IDEs can access
EJB components directly, providing identical business logic to these
clients. In fact, EJB is an ideal component model for isolating user
session activity from business logic and database activity. Combining
EJB with the multiple client models supported by WebLogic Server gives you
complete flexibility in choosing -- and mixing -- application models.
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Increase reliability with transparent fault tolerance
- WebLogic Server clusters provide a significant additional measure
of fault tolerance over prior versions of WebLogic Server. In addition to
transparent scaling with load balancing across multiple servers for
JNDI-based services, clusters can provide redundancy that allows
application clients to continue functioning even in the event of a
server or network failure. In the WebLogic Server model, non-persistent
conversational and stateless JNDI-based services are essentially
immune to server or JNDI instance failures.
WebLogic Server offers a variety of load-balancing and failover models
that can be configured to meet the needs of the
application. WebLogic's intelligent "SmartStubs" for RMI and EJB
objects can select any one of the servers in a cluster during a name
binding. HTTP servlets have cluster-wide session state, and any
invocation of a servlet can be handled by any instance. Servlet
session management is handled through the standard Java Session
Management API, rather than a proprietary solution.
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Integrate with existing applications and databases
- As a component model, WebLogic EJB facilitates integration
of legacy applications and databases into new applications. EJBs can
"wrap" non-Java applications to make it easy to migrate heterogeneous
applications to an easy-to-maintain standard. Once a legacy
application is wrapped inside Enterprise JavaBeans, the business logic
of the legacy application can be converted to Java when business needs
dictate, without impacting new applications or clients.
Similarly, Enterprise JavaBeans can access existing databases
directly or through legacy transaction systems to provide data and
processing to new applications in a component-centric paradigm. As you
migrate your legacy applications to Java or to new systems, the
Enterprise JavaBeans insulate client applications from changes.
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Automate database and transaction programming
- WebLogic EJB provides automatic database access for bean
developers. Using EJB "container-managed" persistence, the WebLogic
EJB container provides the mapping from the user-developed bean to the
underlying database. Datatype conversion, if any, is automatic. The
bean developer can focus completely on the business logic.
Transaction boundaries are also handled automatically by
WebLogic Server. The EJB developer specifies how the bean should relate to a
transaction -- start a transaction, participate in a transaction,
ignore a transaction, and so on.
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Lower costs with reusable components
- WebLogic Server offers multiple programming and component
models. By designing applications with distinct presentation, business
logic, and data/legacy application integration tiers, you can achieve
a high degree of leverage and reuse. For example, common session
Enterprise JavaBeans that contain the logic for business transactions
can be shared by HTML clients, Java application clients, Visual
Basic/C++ clients, and others. The same Enterprise JavaBeans can be
used in many variants of the application. And because business process
information has been abstracted away from the specifics of a single
application interface, those business components can be reused over
and over again in new applications, to significantly reduce cost over
the life cycle of your enterprise applications.
