Why is ejb used

The EJB container provides system-level services to enterprise beans, the bean developer can just concentrate on developing logic to solve business problems. Well worth the time and effort. Transactions, Remoteness, etc. Maybe buy a good EJB book and read it, or do some googling. It probably answers all your initial queries. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow.

Learn more. Why should we use EJB? Asked 10 years, 6 months ago. Active 1 year, 2 months ago. Viewed 52k times. Improve this question. Paul Sasik Sometimes I feel there is a need for stackoverflow to review the guidelines, someone brand new to the technology would like someone to explain in plain English, and what could be better platform than stackoverflow?

Question was asked close to 10 years ago and here I am asking the same question. Add a comment. Active Oldest Votes. Concurrency without use Threads.

All EJBs are instantiated through a pool of objects then your application gains on performance and without Thread complexity. Transactionality through JTA. Beside above, why is Ejb not used anymore? Because we do not write logic to handle issues such as pooling, transaction management, security, etc, applications can be easily scaled as per the requirements.

After all, we leave all this work to the application servers. There is a strong support from many vendors to the EJB specification. There are three types of EJBs: session beans, entity beans, and message-driven beans.

Session Beans. Entity Beans. Message-Driven Beans. Java beans themselves are still very central to Java web applications, just not misused as controllers. Unless you are talking about the similarly named but completely different Enterprise Java Beans EJBs , in which case the answer is, not so much anymore. What is difference between EJB and Spring?

EJB is an architecture for transactional, component-based programming. Spring framework is a Java platform that provides support for developing the Java application. What are EJB containers? The EJB Container. Enterprise beans EJB components are Java programming language server components that contain business logic. The EJB container provides local and remote access to enterprise beans. What is EJB model? Enterprise JavaBeans. EJB is a server-side software component that encapsulates business logic of an application.

A field-group represents a subset of the container-managed persistence CMP and container-managed relation CMR fields of a bean. You can put related fields in a bean into groups that are faulted into memory together as a unit. You can associate a group with a query or relationship, so that when a bean is loaded as the result of executing a query or following a relationship, only the fields mentioned in the group are loaded.

For more information, see Specifying Field Groups. You can configure the behavior of the ejbLoad and ejbStore methods to enhance performance, by avoiding unnecessary calls to ejbStore.

As appropriate, you can ensure that WebLogic Server calls ejbStore after each method call, rather than at the conclusion of the transaction. For more information, see Understanding ejbLoad and ejbStore Behavior. This allows you to avoid the bottlenecks that might otherwise occur when multiple entity instances are affected by a single transaction. For more information, see Ordering and Batching Operations. This optimization improves performance, especially in applications with a high volume of database updates.

If you use the read-mostly pattern, you can use multicast invalidation to maintain data consistency—an efficient mechanism for invalidating read-only cached data after updates. Use of the invalidate method after the transaction update has completed invalidates the local cache and results in a multicast message sent to the other servers in the cluster to invalidate their cached copies.

For more information, see Using the Read-Mostly Pattern. WebLogic Server provides a variety of value-added database access features for entity beans that use container-managed persistence:.

For more information, see Automatically Generating Primary Keys. You can configure the EJB container to automatically change the underlying table schema as entity beans change, ensuring that tables always reflect the most recent object-relationship mapping. This allows you to create and execute new queries without having to update and deploy an EJB. It also reduces the size and complexity of the EJB deployment descriptors.

For more information, see Choosing a Concurrency Strategy. EJBs must be deployed to all clustered servers. A WebLogic Server cluster consists of multiple WebLogic Server server instances running simultaneously and working together to provide increased scalability and reliability. A cluster appears to clients as a single WebLogic Server instance. The server instances that constitute a cluster can run on the same machine, or be located on different machines. Failover and load balancing for EJBs are handled by replica-aware stubs, which can locate instances of the object throughout the cluster.

Replica-aware stubs are created for EJBs as a result of the object compilation process. This allows some bean types to take advantage of load balancing and failover features at the home level when a client looks up an EJB object using the EJBHome stub and at the method level when a client makes method calls against the EJB using the EJBObject stub.

Table , , on page summarizes the load balancing and failover support method level and home level for each EJB type. The bean stub contains the load balancing algorithm or the call routing class used to load balance method calls to the object. On each call, the stub can employ its load algorithm to choose which replica to call. WebLogic Server clusters support multiple algorithms for load balancing clustered EJBs; the default is the round-robin method. All bean types support load balancing at the home level.

All bean types, except read-write entity beans, support load balancing at the method level. When a client makes a call through a stub to a service that fails, the stub detects the failure and retries the call on another replica. EJB failover requires that bean methods must be idempotent, and configured as such in weblogic-ejb-jar. Table summarizes failover and load balancing features for clustered EJBs.

This script outputs the product breadcrumb required for edocs documentation. Send confirmation of authorization to the JSP. Call a bean that accesses profile information for the authorized user. The remote interface exposes business logic to remote clients—clients running in a separate application from the EJB. It defines the business methods a remote client can call.

The local interface exposes business logic to local clients—those running in the same application as the EJB.

It defines the business methods a local client can call. The local home interface, also referred to as an EJB factory or life-cycle interface, provides methods that local clients—those running in the same application as the EJB—can use to create, remove, and in the case of an entity bean, find instances of the bean. The remote home interface, also referred to as an EJB factory, or life-cycle interface, provides methods that remote clients—those running in a separate application from the EJB—can use to create, remove, and find instances of the bean.

Only entity beans have a primary key class. The primary key class maps to one or more fields in a database—identifying the persistent data to which the entity bean corresponds. Life-cycle management Code generation Persistence management Security Transaction management Locking and concurrency control. All beans must be specified in an ejb-jar.

An ejb-jar. This file is required if your beans take advantage of WebLogic Server-specific features. Like ejb-jar.