Transaction support in WebSphere Application Server:

A transaction is unit of activity within which multiple updates to resources can be made atomic (as an indivisible unit of work) such that all or none of the updates are made permanent. For example, multiple SQL statements to a relational database are committed atomically by the database during the processing of an SQL COMMIT statement. In this case, the transaction is contained entirely within the database manager and can be thought of as a resource manager local transaction (RMLT). In some contexts, a transaction is referred to as a logical unit of work (LUW).

The way that applications use transactions depends on the type of application component, as follows:

WAS is a transaction manager that supports the coordination of resource managers through their XAResource interface and participates in distributed global transactions with other OTS 1.2 compliant transaction managers (for example J2EE 1.3 appservers). WebSphere applications can also be configured to interact with databases, JMS queues, and JCA connectors through their local transaction support when distributed transaction coordination is not required.

Resource managers that offer transaction support can be categorized into those that support two-phase coordination (by offering an XAResource interface) and those that support only one-phase coordination (for example through a LocalTransaction interface). WAS transaction support provides coordination, within a transaction, for any number of two-phase capable resource managers. It also enables a single one-phase capable resource manager to be used within a transaction in the absence of any other resource managers, although a WebSphere transaction is not necessary in this case.

Last Participant Support

With the Last Participant Support of WAS Enterprise, you can coordinate the use of a single one-phase commit (1PC) capable resource with any number of two-phase commit (2PC) capable resources in the same global transaction. At transaction commit, the two-phase commit resources are prepared first using the two-phase commit protocol, and if this is successful the one-phase commit-resource is then called to commit(one_phase). The two-phase commit resources are then committed or rolled back depending on the response of the one-phase commit resource.

ActivitySession

The ActivitySession service of WAS Enterprise provides an alternative unit-of-work (UOW) scope to that provided by global transaction contexts. It is a distributed context that can be used to coordinate multiple one-phase resource managers. The WebSphere EJB container and deployment tooling support ActivitySessions as an extension to the J2EE programming model. EJBs can be deployed with lifecycles that are influenced by ActivitySession context, as an alternative to transaction context. An application can then interact with a resource manager through its LocalTransaction interface for the period of a client-scoped ActivitySession rather than just the duration of an EJB method.

WebSphere is a trademark of the IBM Corporation in the United States, other countries, or both.

IBM is a trademark of the IBM Corporation in the United States, other countries, or both.