You 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.
Before you begin
During the time that 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.
About this task
Add a maintenance level to an external system resource that
is used by the deployed message-driven bean (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 that the MDB or SCA composite is paused, and that the
MDB or SCA composite has resumed. Consider registering a message listener
on the JCA MBean to receive the JMX notifications.
Procedure
- Navigate to the deployed enterprise application that contains
the MDB, or the business-level application that contains the SCA composite.
- From the MDB or SCA composite, navigate to its JMS activation
specification. Click and
click Pause on the administrative panel for
the MDB or SCA composite.
- When you receive a JMX notification and a log entry indicating
that 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.
- Restart the database and test that it is working as expected.
- Log on to the administrative console again, navigate to
the same enterprise or business-level application and click Resume on
the administrative panel for the MDB or SCA composite. You can also
resume the MDB or SCA composite by 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.