WAS v8.5 > Administer applications and their environment > Welcome to administering Messaging resources > Manage messaging with the default messaging provider > Configure resources for the default messaging provider > Protecting an MDB or SCA application from system resource problems

Example 1: Handling a planned outage of an MDB or SCA application external resource

We can configure the system so that, if there is a problem with a dependent external system resource, the enterprise or business-level application can continue.

During the time the system resource is unavailable, there must be no exceptions in the enterprise or business-level application, or messages on the exception destination that must be resolved later.

Add a maintenance level to an external system resource used by the deployed MDB of one of the enterprise or business-level applications. The act of applying the maintenance level requires the system resource (for example, a database) to be unavailable for about five minutes.

The JCA MBean emits JMX notifications to indicate the MDB or SCA composite is paused, and the MDB or SCA composite has resumed. Consider registering a message listener on the JCA MBean to receive the JMX notifications.

1. cd deployed enterprise application containing the MDB, or the business-level application containing the SCA composite.

2. From the MDB or SCA composite, navigate to its JMS activation specification. Click Resources -> JMS -> Activation specifications -> activation_specification_name and click Pause on the administrative panel for the MDB or SCA composite.

3. When you receive a JMX notification and a log entry indicating the MDB or SCA composite is paused, stop the database and apply the maintenance level. While the MDB or SCA composite is paused, no messages are sent to the exception destination and no error messages appear in the console related to the stopped database.
4. Restart the database and test that it is working as expected.
5. Log on to the dmgr console again, navigate to the same enterprise or business-level application and click Resume on the administrative panel for the MDB or SCA composite. We can also resume the MDB or SCA composite using scripting and the JCA MBean. The initial JMX notification and log entry indicate which MBean to use to resume the MDB or SCA composite. The MDB or SCA composite begins to be driven with the messages that are on the destination.

Results

You have paused and resumed an application while an external resource that it uses is not available for a short time.

+

Search Tips   |   Advanced Search