Resolving problems when debugging message flows

This topic contains advice for dealing with some of the common problems that can arise when debugging message flows.

The debugger does not pause at the next breakpoint

Procedure

  • Scenario: The message flow debugger does not pause at the next breakpoint in your message flow.
  • Solution: Perform the following checks:
    1. Check whether your DataFlowEngine is running; if it is not, restart it.
    2. Check the input queue. If your input queue has the leftover messages from the previous time that you used the debugger, clear them before you send a new message.

The message does not stop executing at any breakpoint

Procedure

  • Scenario: The message does not stop executing at any breakpoint after you attach to the debugger.
  • Explanation: This error could be caused by a timing problem, or if you have set the wrong parameters for the debug session.
  • Solution: Perform the following steps.
    1. Check your launch configuration settings, ensuring that you have specified the correct Flow Project, HostName and Flow Engine for the debug session.
    2. Restart the debug session.

Editing problems occur in the Message Flow editor

Procedure

  • Scenario: While debugging a message flow, editing problems occur when you are using the Message Flow editor.
  • Solution: Do not attempt to edit the message while the flow debugger is attached. To edit a message flow, detach the debugger, edit the message flow, then redeploy the message flow.

Editing the MQ message descriptor (MQMD) causes unexpected behavior in the debugger

Procedure

  • Scenario: You edit properties of the message MQMD descriptor in the Message Set editor, but this causes unexpected behavior in the debugger.
  • Explanation: If you edit the content of the MQMD descriptor, these fields take a certain range of values.
    You need to know these ranges before editing the properties. Unless you explicitly specify the value of these fields, they take default values, and certain fields might not have been specified in the message. The values in the fields that are not set explicitly in the message are default values; do not change these unless you are aware of their importance or the possible range of values.

You cannot see the message content when debugging your message flow

Procedure

  • Scenario: You are using the message flow debugger, and you can see the message passing through the message flow, but you cannot see the content of the message.
  • Solution: Open the Flow Debug Message view by clicking Window > Show View > Other > Message Flow > Flow Debug Message, then OK.

An exclamation mark appears above a node during debugging

Procedure

  • Scenario: In the Message Flow editor, an exclamation mark (!) is displayed above a node during debugging.
  • Explanation: An exception has occurred in the node during debugging.
  • Solution: Look under the ExceptionList in the Variables view of the Debug perspective to find out what error has occurred.

The message does not stop processing at breakpoints

Procedure

  • Scenario: Message processing continues when a breakpoint is encountered.
  • Explanation: This error could be caused by a timing problem, or if you have set the wrong parameters for the debug session.
  • Solution: Check your launch configuration setting. Ensure you have specified the correct Flow Project, HostName and Flow Engine for the debug session. Restart the debug session.

You cannot see where the debugger is in the Graphical Data Mapping editor

Procedure

  • Scenario: The Graphical Data Mapping editor has opened in the IBM® Integration Toolkit, but it is unclear where the debugger is in the map.
  • Explanation: The source lookup path for the message map file is not configured correctly.
  • Solution: Check your debug launch configuration settings and ensure you have configured the source lookup path for the message map file correctly.

When debugging a message map, the debugger does not move to the next field

Procedure

  • Scenario: You are debugging a message map, and the debugger does not move to the next field. You have to click the Step over button multiple times.
  • Explanation: The source lookup path for the message map file is not configured correctly.
  • Solution: Check your debug launch configuration settings and ensure you have configured the source lookup path for the message map file correctly.

When debugging a message map, the debugger does not move out of the mapping node

Procedure

  • Scenario: You are debugging a message map, and the debugger does not move out of the message map.
  • Explanation: The source lookup path for the message map file is not configured correctly.
  • Solution: Check your debug launch configuration settings and ensure you have configured the source lookup path for the message map file correctly.

The message flow stops at a collector node

Procedure

  • Scenario: Message processing stops after selecting the Step into Source Code icon on a Collector node.
  • Explanation: The collector node is a multithreaded node and the thread is ended by selecting Step into Source Code.
  • Solution: Set a breakpoint manually after the collector node.