What is Concurrency and how do I configure Concurrency Properties in Deploy Tool for CMP Beans?

Enterprise applications often try to balance scalability and concurrency issues. Concurrency defines how the EJB container should manage concurrent access to an entity bean. Click the Concurrency tab to edit the concurrency properties for entity beans. The concurrency modes supported in Server are:

• Repeatable Read
• Optimistic Repeatable Read - set this to verify all, modified, or modified and accessed fields
• Read Committed
• Read Only

The optimizations can be performed using either of the two database access methods:

• Exclusive: Optimization in this case is performed assuming that the bean exclusively accesses the database table. The data in this case, is not modified by any external source. Since, container has exclusive access to the database, it can cache the entity state and achieve load optimization.
• Non-Exclusive: Container cannot cache the entity state. Since the data is modified from external sources, the Container has to use database locking to achieve data integrity.

You can either select to update all the CMP fields, or only the modified CMP fields. You can also use this screen to specify whether you want to indert the bean after ejbcreate, ejbPostcreate, or at the end-of-transaction.

© Pramati Technologies 2007	Runs on Pramati Server | Feedback | Legal