Advanced Java Programming - Enterprise Java Beans client
- 1. Presented By S.Vijayalakshmi B.E, Assistant Professor, Department of Computer Science, Sri Sarada Niketan College for Women, Karur. EJB CLIENTS
- 2. An EJB client is any kind of application that accesses and invokes business logic of EJB components deployed inside the EJB engine. EJB clients thus include Servlets, applets, other EJBs, standalone Java programs, etc. WHAT ARE EJB CLIENTS?
- 3. EJB is a server-side software component that encapsulates business logic of an application. An EJB web container provides a runtime environment for web related software components, including computer security, Java servlet lifecycle management, transaction processing, and other web services. WHAT ARE THE APPLICATIONS OF EJB?
- 4. Application needs Remote Access. In other words, it is distributed. Application needs to be scalable. EJB applications supports load balancing, clustering and fail-over. Application needs encapsulated business logic. EJB application is differentiated from demonstration and persistent layer. WHEN TO USE ENTERPRISE JAVA BEANS?
- 5. The EJB object implementation itself must implement all the remote methods defined in its remote interface, provide methods that correspond to the methods on its home interface for creating and/or finding the bean, and also implement the methods used by the EJB container to manage the bean. EJB IMPLEMENTATION
- 6. These sections discuss design options for WebLogic Server Enterprise Java Beans (EJBs), bean behaviors to consider during the design process, and recommended design patterns. Choosing the Right Bean Type Persistence Management Alternatives Transaction Design and Management Options Satisfying Application Requirements with WebLogic Server EJBs. DESIGNING ENTERPRISE JAVA BEANS
- 7. When you choose the bean type for a processing task, consider the different natures and capabilities of the various bean types. Bean types vary in terms of the bean’s relationship with its client. Some bean types stick with a client throughout a series of processes, serving as a sort of general contractor—acquiring and orchestrating services for the client. There are other bean types that act like subcontractors, they deliver the same single function to multiple client-oriented general contractor beans. Beans that deliver commodity services to multiple client-oriented beans do not maintain state. CHOOSING THE RIGHT BEAN TYPE
- 8. Persistence management strategy determines how an entity bean’s database access is performed. Configure the persistence management strategy either container-managed or bean-managed for an entity bean in the persistence-type element in ejb- jar.xml. PERSISTENCE MANAGEMENT ALTERNATIVES
- 9. A transaction is a unit of work that changes application state—whether on disk, in memory or in a database—that, once started, is completed entirely, or not at all. Transactions are costly application resources, especially database transactions, because they reserve a network connection for the duration of the transaction. TRANSACTION DESIGN AND MANAGEMENT OPTIONS
- 10. Transaction Isolation: A transaction’s isolation level is the degree to which it exposes updated but uncommitted data to other transactions. Allowing access to uncommitted data can improve performance, but increases the risk of incorrect data being supplied to other transactions. Set the isolation level for bean-managed transactions in the bean’s Java code. For instructions, see Programming Bean-Managed Transactions . Set the isolation level for container-managed transactions in the isolation-level sub-element of the transaction-isolation element of weblogic-ejb-jar.xml. Web Logic Server passes this value to the underlying database. The behavior of the transaction depends both on the EJB’s isolation level setting and the concurrency control of the underlying persistent store. A PERFORMANCE VS. DATA CONSISTENCY CHOICE
- 11. Satisfying Application Requirements with WebLogic Server EJBs. WebLogic Server offers a variety of value- added features for enterprise beans that you can configure to meet the requirements of your application. SATISFYING APPLICATION REQUIREMENTS
- 12. EJB repository yields system-level services to enterprise beans, the bean developer can focus on solving business problems. Rather than the bean developer, the EJB repository is responsible for system-level services such as transaction management and security authorization. Enterprise Java Beans are portable elements, the application assembler can build new applications from the beans that already exists. ADVANTAGES OF EJB
- 13. Requires application server. Requires only java client. For other language client, you need to go for web service. Complex to understand and develop EJB applications. DISADVANTAGES OF EJB
- 14. THANK YOU