IBM WebSphere: Deployment and Advanced Configuration

Dealing with Isolation Levels in CMP

In Chapter 7, we learned how JDBC uses resource references to communicate the desired isolation level to the underlying database. This allows the database to acquire the correct type of lock for the specific transaction. However, with CMP, the database layer is abstracted, and therefore we need a way to communicate desired isolation levels to the underlying data store. In addition, there are other settings that need finer-grain control. For example, earlier, we illustrated that we can have a collection of CMPs. An application may need to iterate through the collection. With large collections, the application may need to only iterate through a subset of that data. We need a mechanism that allows you to only ...