This topic provides an overview of the high-level tasks
for using ActivitySessions in enterprise applications.
About this task
Before you use ActivitySessions in enterprise applications,
consider the following points:
- An application that is accessed under an ActivitySession context
can receive a javax.transaction.InvalidTransactionException RemoteException,
thrown by the Enterprise JavaBeans (EJB)
container when servicing any application method. This exception occurs
when an instance of an enterprise bean that has an ActivitySession-based
activation policy becomes involved with concurrent global and local
transactions.
- To enable an enterprise bean to participate in an ActivitySession
context and support ActivitySession-based operations, it must be configured
with an ActivationPolicy of ACTIVITY_SESSION. A bean configured with
ActivationPolicy of either TRANSACTION or ONCE cannot participate
in an ActivitySession context.
- A session bean can either use container-managed ActivitySessions
or implement bean-managed ActivitySessions; entity beans can use only
container-managed ActivitySessions. A bean is deployed to be bean-managed
or container-managed with respect to ActivitySession management by
setting its transaction type deployment attribute to be bean-managed
or container-managed when you deploy the enterprise bean. A bean that
uses bean-managed transactions can use bean-managed ActivitySessions;
a bean that uses container-managed transactions can use container-managed
ActivitySessions.
- If you want a session bean or an enterprise application client
to manage its own ActivitySessions, you must write the code that explicitly
demarcates the boundaries of an ActivitySession, as described in Developing an enterprise
bean or J2EE client to manage ActivitySessions.
The following high level tasks illustrate how to use an ActivitySession
in an enterprise application:
Procedure
- Develop an enterprise application that uses one or more
enterprise beans that are persisted to non-transactional data stores.
Use this approach for an application that needs to coordinate
multiple one-phase resource managers, for example, for two or more
entity enterprise beans whose persistence is delegated to LocalTransaction
resource adapters.
In this scenario, the enterprise beans that
the application uses have an Activation policy of ActivitySession
and a local transaction containment policy with a boundary of ActivitySession
and resolution-control of ContainerAtBoundary. The container synchronizes
the EJB state data with the one-phase resource managers at ActivitySession
completion, and no application code needs to be aware of ActivitySession
support.
- Develop an enterprise application in which an enterprise
bean accesses a resource manager multiple times in different business
methods. Use this approach for an application that needs
to extend a resource manager local transaction (RMLT) over several
business methods of an enterprise bean instance.
In this scenario,
the enterprise beans that the application uses have an Activation
policy of ActivitySession and a local transaction containment policy
with a boundary of ActivitySession and resolution-control of Application.
The application logic starts and ends the RMLTs, for example, using
the javax.resource.cci.LocalTransaction interface offered by a LocalTransaction
Connector, but is not constrained to start and commit the LocalTransaction
in the same method.
- Develop an enterprise client application to use an ActivitySession
to scope EJB activation and load-balancing. Use this approach
for an application client that needs to access an entity bean instance
several times in the same client session, either without needing to
run under a transaction context, or with the need to run under a number
of distinct and serially-executed transactions.
In this scenario,
the enterprise beans that the application uses have an Activation
policy of ActivitySession and a local transaction containment policy
appropriate to the function of the enterprise bean. The enterprise
client application can represent a period of user activity, for example
a signon period, during which a number of interactions occur with
one or more enterprise beans. If the enterprise client application
begins an ActivitySession and invokes the enterprise beans within
the scope of the unit of work (UOW) that the ActivitySession represents,
the container on the ActivitySession boundary activates the enterprise
bean instances. The instances remain in the active state until the
container passivates them at the end of the ActivitySession. Workload
affinity management based on the ActivitySession is a platform quality
of service. Global transactions can begin and end within the ActivitySession,
if they are wholly encapsulated by the ActivitySession and run serially.
EJB instances that are activated at the ActivitySession boundary remain
active across the serial global transactions.
- Develop a Web application client to participate in an ActivitySession
context. A Web application that runs in the WebSphere® Web
container can participate in an ActivitySession context. Web applications
can use the UserActivitySession interface to begin and end an ActivitySession
context. Also, the ActivitySession can be associated with an HttpSession,
thereby extending access to the ActivitySession over multiple HTTP
invocations and supporting EJB activation periods that can be determined
by the lifecycle of the Web HTTP client.
The Web container manages
ActivitySessions based on deployment descriptor attributes associated
with the Web application module.
Example
For examples of using ActivitySessions in enterprise applications,
see the topic about ActivitySessions samples.