This topic describes how to investigate why messages are not being
consumed at a destination on a service integration bus, when the messages
are being routed through a remote message point and the consuming application
is stopped.
Before you begin
Why and when to perform this task
Perform this task as part of either
Investigating why point-to-point messages are not being consumed or
Investigating why publish/subscribe messages are not arriving at a subscription. This task explains
how to investigate the flow of messages in a scenario where the messages are
being routed through a remote message point and the consuming application
is stopped.
The following diagrams illustrate two
possible scenarios. In Figure 1, ME2 is the messaging engine that hosts the
message point, and receives messages from the producing application through
ME1. ME3 is the messaging engine that the consuming application is attached
to, and hosts a remote message point which represents the message point on
ME2. In Figure 2, ME2 and ME3 host publication points that are represented
by remote publication points on ME1, where the producing application is attached.
Subscribing application B is connected to ME3 and receives messages indirectly
from ME1, via a subscription on ME2. a remote subscription point on ME 3.
These messaging engines are referred to in the following steps.Figure 1. Point-to-point message consumption using a remote message point
Figure 2. Publish/subscribe messaging using a remote message point
Steps for this task
- If you have followed the steps in Investigating why point-to-point messages are not being consumed or Investigating why publish/subscribe messages are not arriving at a subscription before starting this
task, you should have displayed a list of message requests. On the previous
panel (runtime properties for the message point), check that
the Message requests issued (point-to-point only) or Message
requests received (publish/subscribe only) value is greater than
zero. If the value is not greater than zero, no requests have been made. Check
the consuming application for errors:
- Check that the application is actually connected to ME2.
- Check that the application did not produce any errors which could explain
why messages are not being consumed.
- Check that the consumer was started.
- Check that the application did attempt to consume a message:
- If the application uses an asynchronous consumer, check that the asynchronous
consumer was registered.
- If the application is synchronous, check that the consumer performed a
'receive' or a 'receive with wait' function (this may require a modification
to the application to extend the time that the application waits for a message).
- If the number of issued message requests is greater than zero,
requests from ME3 to ME2 for messages on the message point have been made.
Check that the Completed message requests value is
greater than zero. If not, check that the two messaging engines can communicate
with each other, see Service integration troubleshooting: Checking the communication between two messaging engines in a bus.
- If the number of completed message requests is greater than zero,
requests are being issued by ME3, processed by ME2 and completed back to ME3.
To ensure that those requests were made by the actual application being investigated,
record the current values of Completed message requests and
either Message requests issued or Message
requests received. Rerun the consuming application and check that
both values have increased. If the values do not increase, the application
did not make a request from ME3 to ME2 for this message point (the existing
numbers relate to a previous application that was consuming messages). Check
the consuming application for errors:
- Check that the application was started.
- Check that the name of the destination being consumed from is correct.
- If the values do increase, the message request was issued and completed,
but no message was returned or processed by the consuming application.
- Check that the application's selection criteria match the available message
or messages on the message point.
- Check that the application is correctly receiving the message, by checking
for application or runtime errors.
If you are still having problems, contact your IBM customer service
representative.