Attaching to the flow engine

Before you start

To complete this task, you must have completed the following tasks:

Before you can debug your message flow, you must attach the flow debugger to the flow engine (execution group) where your flow is deployed. If you want to, you can attach the flow debugger to multiple flow engines that are running on the same or different host machines and then simultaneously debug their flows.

To attach to the flow engine:

  1. Switch to the Flow Debug perspective.
  2. Click the Attach to Flow Runtime icon Attach to Flow Runtime on the toolbar to invoke the Attach to the Flow Engine wizard.
  3. If the host computer that contains the flow engine does not appear in the Hosts list box, enter the host name or IP address of the host computer in the Hostname or IP field, then click Add to add the host to the Hosts list box.
  4. In the Hosts list box, select the host computer that the flow engine is running on and click Next.
  5. In the list box that opens, each flow engine is listed as the name of the broker, followed by a colon, followed by the name of the execution group, followed by the process number in brackets, for example: WMQIV5BR:default[2724]. If the flow engine does not appear in the list box, click Refresh to update the list box with the names of all flow engines that are currently deployed and available on the host computer. (If the flow engine still does not appear in the list box, try restarting IBM Agent Controller on the host computer).
    Note: You will be presented with the option of attaching to any execution group running on the target host. This includes execution groups that do not have any flows deployed.
    Tip: The process number is the Windows PID, as listed in the Task Manager on the Processes page. The PID was reported to you in the Event Log when you deployed, as described in Deploying a publish/subscribe topology.
  6. In the list box, select the flow engine containing the flow that you want to debug, then click Finish. In the Flow Debug view, the names of the selected host computer and flow engine are displayed, as well as the names of the flows that are deployed in the flow engine.
  7. In the Flow Debug view of the Flow Debug perspective, double-click the message flow that you want to debug. The message flow opens in the Message Flow editor.
  8. In the Message Flow editor, add a breakpoint to a connection that leads out of the input node of the message flow. Adding this breakpoint ensures that the message flow does not run to completion before you can begin to debug it.

    The breakpoint appears as Enabled global breakpoint. (For information about adding a breakpoint, see Working with breakpoints).

  9. When the next message comes into your flow and arrives at the breakpoint, the flow pauses, the breakpoint icon changes to  Enabled paused global breakpoint , and you can start debugging.
Tip: From a single workbench, the debugger can attach to more than one execution group, and debug multiple flows in different execution groups (and therefore multiple messages) at the same time. However, a deployed flow in one execution group can be debugged by only one user at a time, so if you attach your debugger to it, another user cannot also attach a debugger at the same time.
Note: The flow debugger provided in Fix Pack 3 can debug runtime brokers from either Fix Pack 2 or Fix Pack 3. You can select the version of the broker that you want to debug by checking the corresponding option in the Flow Debug preference page (see Setting flow debug preferences) with the default set to Message Broker CSD3 and beyond.
The following table shows what is supported on different platforms:
  CSD3 Broker + RAC 5.0.2 CSD2 Broker + RAC 5.0.2 CSD2 Broker + RAC 5.0.1
Windows Yes Yes Yes
AIX Yes Yes Yes
Solaris Yes Yes No
HP-UX Yes No No
z/OS Yes No No
Linux Yes (with IFix) No No
(The available options show CSD2 or CSD3; these terms refer to Fix Pack 2 or Fix Pack 3.)

Contact your IBM Support Center if you want to use the flow debugger with a Fix Pack 3 broker on Linux.

Related concepts
Flow debugger overview
Related tasks
Debugging a message flow
Working with breakpoints
Detaching from the flow engine
Related reference
Flow debugger shortcuts
Flow debugger icons and symbols