Chapter 6. To Debug a Routing Context

This tutorial shows how to use the Camel debugger for only a locally running routing context. The routing context and each node with a breakpoint set must have a unique ID. The tooling automatically assigns a unique ID to the camelContext element and to components and patterns dropped on the canvas, but you can change these IDs to customize your project.

Goals

In this tutorial you will:

  • In the Design tab, set breakpoints on the nodes of interest in Route1
  • Switch to Route2, and set breakpoints on the nodes of interest
  • Invoke the Camel debugger
  • Step through the route, examining route and message variables as they change
  • Step through the route again, changing the value of message variables and observing the effects

Prerequisites

To complete this tutorial you will need the CBRroute project you updated in Chapter 5, To Add Another Route to the CBR Routing Context.

Note

If you skipped any tutorial after Chapter 2, To Create a New Route you can use the prefabricated blueprintContext6.xml file to work through this tutorial (for details, see Chapter 1, Using the Fuse Tooling Resource Files).

Setting breakpoints

You can set both conditional and unconditional breakpoints, but in this tutorial, you will set unconditional breakpoints only.

  1. If necessary, open your CBRroute/src/main/resources/OSGI-INF/blueprint/blueprint.xml in the route editor.
  2. In Project Explorer, expand Camel Contexts/src/main/resources/OSGI-INF/blueprint to expose both route entries.
  3. Double-click the Route_route1 entry to switch focus to Route_route1 in the Design tab.
  4. On the canvas, select the Choice_choice1 node, and then click its red icon icon to set an unconditional breakpoint:

    BPnodeIcons
    forward nav
    BPnodeIcons2
    Note

    In the route editor, you can disable or delete a specific breakpoint by clicking the node’s gray icon icon or its delete icon icon, respectively. You can delete all set breakpoints by right-clicking the canvas and selecting Delete all breakpoints.

  5. Repeat [setBPstep] to set an unconditional breakpoint on the following Route_Route1 nodes:

    • Log_log1
    • SetHeader_setHeader1
    • To_Invalid
    • Log_log2
    • SetHeader_setHeader2
    • To_Fulfill
  6. In Project Explorer, double-click Route_route2 under src/main/resources/OSGI-INF/blueprint to open Route_route2 on the canvas.
  7. Repeat [setBPstep] to set an unconditional breakpoint on the following Route_Route2 nodes:

    • Choice_choice2
    • SetHeader_setHead_usa
    • Log_usa
    • To_US
    • SetHeader_setHead_uk
    • Log_uk
    • To_UK
    • SetHeader_setHead_ger
    • Log_ger
    • To_GER
    • SetHeader_setHead_fr
    • Log_fr
    • To_FR

Stepping through the CBRroute routing context

You can step through the routing context in two ways:

  • Step over ( Step Over icon ) - Jumps to the next node of execution in the routing context, regardless of breakpoints.
  • Resume ( Resume icon ) - Jumps to the next active breakpoint in the routing context.
Note

You can temporarily narrow then later re-expand the debugger’s focus by disabling and re-enabling the breakpoints you set in the routing context. This enables you, for example, to focus on problematic nodes in your routing context. To do so, open the Breakpoints tab and clear the check box of each breakpoint you want to temporarily disable. Then use Resume icon to step through the route. The debugger will skip over the disabled breakpoints.

  1. In Project Explorer, expand the root node CBRroute to expose the blueprint.xml file in the Camel Contexts folder.
  2. Right-click the blueprint.xml file to open its context menu, and then click menu:Debug As…​[ > > Local Camel Context > ].

    The Camel debugger suspends execution at the first breakpoint it encounters and asks whether you want to open Debug perspective now:

    tutCnfrmPerspSwitch
  3. Click Yes.

    Note

    If you click No, the confirmation pane appears several more times. After the third refusal, it disappears, and the Camel debugger resumes execution. To interact with the debugger at this point, you need to open the Debug perspective by clicking menu:Window[ > > Open Perspective > > Debug > ].

    Debug perspective opens with the routing context suspended at _choice1 in Route1 [blueprint.xml] as shown in the Debug view:

    tutDebugPerspOpen1
    Note

    Breakpoints are held for a maximum of five minutes before the debugger automatically resumes, moving on to the next breakpoint or to the end of the routing context, whichever comes next.

  4. In the Variables view, expand the nodes to expose the variables and values available for each node.

    As you step through the routing context, the variables whose values have changed since the last breakpoint are highlighted in yellow. You may need to expand the nodes at each breakpoint to reveal variables that have changed.

  5. Click Resume icon to step to the next breakpoint, _log2 in Route1 [blueprint.xml]:

    tutDBResumeLog2Rte1
  6. Expand the nodes in the Variables view to examine the variables that have changed since the last breakpoint at _choice1 in Route1 [blueprintxt.xml].
  7. Click Resume icon to step to the next breakpoint, _setHeader2 in Route1 [blueprint.xml].

    Examine the variables that changed since the breakpoint at _log2 in Route1 [blueprint.xml].

  8. In the Debug view, click _log2 in Route1 [blueprint.xml] to populate the Variables view with the variable values from the breakpoint _log2 in Route1 [blueprint.xml] for a quick comparison.

    In the Debug view, you can switch between breakpoints within the same message flow to quickly compare and monitor changing variable values in the Variables view.

    Note

    Message flows can vary in length. For messages that transit the InvalidOrders branch of Route_route1, the message flow is short. For messages that transit the ValidOrders branch of Route_route1, which continues on to Route_route2, the message flow is longer.

  9. Continue stepping through the routing context. When one message completes the routing context and the next message enters it, the new message flow appears in the Debug view, tagged with a new breadcrumb ID:

    tutDBviewNextMsg

    In this case, ID-janemurpheysmbp-home-55846-1471374645179-0-3 identifies the second message flow, corresponding to message2.xml having entered the routing context. Breadcrumb IDs are incremented by 2.

    Note

    Exchange and Message IDs are identical and remain unchanged throughout a message’s passage through the routing context. Their IDs are constructed from the message flow’s breadcrumb ID, and incremented by 1. So, in the case of message2.xml, its ExchangeId and MessageId are ID-janemurpheysmbp-home-55846-1471374645179-0-4.

  10. When message3.xml enters the breakpoint _choice1 in Route_route1 [blueprint.xml], examine the Processor variables. The values displayed are the metrics accumulated for message1.xml and message2.xml, which previously transited the routing context:

    tutMsg3Choice1Stats

    Timing metrics are in milliseconds.

  11. Continue stepping each message through the routing context, examining variables and console output at each processing step. When message6.xml enters the breakpoint To_GER in Route2 [blueprint.xml], the debugger begins shutting down the breadcrumb threads.
  12. In the Menu bar, click Terminate icon to terminate the Camel debugger. This will cause the Console to terminate, but you will have to manually clear the output.

    Note

    With a thread or endpoint selected under the Camel Context node in the Debug view, you need to click Terminate icon twice - first to terminate the thread or endpoint and second to terminate the Camel Context, thus the session.

  13. In the Menu bar, right-click tutDebugPersp to open the context menu, and then select Close to close Debug perspective.

    Doing so automatically returns you to perspective from which you launched the Camel debugger.

  14. In Project Explorer, open the project’s context menu, and select Refresh to refresh the display.

    Note

    If you terminated the session prematurely, before all messages transited the routing context, you might see, under the CBRroute/src/data folder, a message like this: message3.xml.camelLock. You need to remove it before you run the debugger on the project again. To do so, double-click the .camelLock message to open its context menu, and then select Delete. When asked, click OK to confirm deletion.

  15. Expand the CBRroute/target/messages/* directories to check that the messages were delivered to their expected destinations:

    tutDualCBRrteVerify
  16. Leave the routing context as is, with all previous breakpoints set and enabled.

Changing the value of a variable

In this session, you will add variables to a watch list to easily check how their values change as messages pass through the routing context. You will also change the value of a variable in the body of two messages and observe how the change affects each message’s route through the routing context.

  1. Follow [startDebugger1] through [startDebugger3] in the section called “Stepping through the CBRroute routing context” to rerun the Camel debugger on the CBRroute project.
  2. With message1 stopped at the first breakpoint, _choice1 in Route1 [blueprint.xml], add the variables NodeId and RouteId (in the Exchange category) and MessageBody and CamelFileName (in the Message category) to the watch list.

    For each of the four variables:

    1. In the Variables view, expand the appropriate category to expose the target variable:
    2. Right-click the variable (in this case, NodeId in the Exchange category) to open the context menu and select Watch:

      FTVarNodeIDWatch

      The Expressions tab opens, listing the variable you selected to watch:

      FTWatchM1NodeId
    3. Repeat [selectVariable] for each of the three remaining variables.
    4. Switch back to the Variables view.
  3. Step message1 through the routing context until it reaches the fourth breakpoint, _Fulfill in Route1 [blueprint.xml].
  4. In the Variables view, expand the Message category.
  5. Repeat [selectVariable] to add the variable Destination to the watch list.

    The Expressions view should now contain these variables:

    FTWatchM1R1toFfil
    Note

    The pane below the list of variables displays the value of the selected variable.

    Note

    The Expressions view retains all variables you add to the list until you explicitly remove them.

  6. Step message1 through the rest of the routing context.
  7. Stop message2 at _choice1 in Route1 [blueprint.xml].
  8. In the Variables view, expand the Message category to expose the MessageBody variable.
  9. Right-click MessageBody to open its context menu, and select Change Value…​:

    tutVarChngMenuMsg2
  10. Change the value of quantity from 3 to 2:

    tutChgVarsMsg2

    This changes the in-memory value only.

  11. Click OK.
  12. Switch to the Expressions view, and select the MessageBody variable.

    The pane below the list of variables displays the entire body of message2, making it easy to check the current value of order items:

    FTWatchM2R1toFfilVarChng
    Note

    Creating a watch list makes it easy for you to quickly check the current value of multiple variables of interest.

  13. Click Resume icon to step to the next breakpoint.

    Instead of following the branch leading to To_Invalid, message2 now follows the branch leading toTo_Fulfill and Route_route2:

    tutCamCntxtMsg2toFulfill
  14. Step message2 through the routing context, checking the Debug view, the Variables view, and the Console output at each step.
  15. Stop message3 at _choice1 in Route1 [blueprint.xml].
  16. Switch to the Breakpoints view, and disable all breakpoints (13) listed below _choice1:

    tutBreakptsDisabled
  17. Click Resume icon to step to the next breakpoint:

    tutMsg3toFulfillRte1

    The debugger jumps to _FulFill in Route1 [blueprint.xml].

  18. Click Resume icon again to step to the next breakpoint:

    tutMsg3toUKRte2

    The debugger jumps to _UK in Route2 [blueprint.xml].

  19. In the Breakpoints view, re-enable all disabled breakpoints.
  20. Switch back to the Variables view.
  21. Click Resume icon to step to the next breakpoint, and stop message4 at _choice1 in Route1 [blueprint.xml].
  22. Right-click MessageBody to open its context menu, and select Change Value…​.
  23. Change the value of quantity from 5 to 4:

    tutChnVarMsg4
  24. Click OK.
  25. Switch to the Expressions view, and select the MessageBody variable to check the value of quantity in the body of message4.
  26. Repeat [varChgRestart1] and [varChgRestart2] to step message4 through the routing context.
  27. Click Resume icon repeatedly to quickly step message5 and message6 through the routing context.
  28. In the tool bar, click Terminate icon to terminate the Camel debugger:

    tutDBTerminateNorm

    This will also cause the Console to terminate, but you will have to click its Clear output icon button to clear the output.

  29. In the Menu bar, right-click tutDebugPersp to open the context menu, and then select Close to close Debug perspective.

    Doing so automatically returns you to the perspective from which you launched the Camel debugger.

  30. In Project Explorer, open the project’s context menu, and select Refresh to refresh the display.
  31. Expand the CBRroute/target/messages/* directories to check whether the messages were delivered as expected:

    tutPETargetDestsChngedVars

    You should see that no messages were sent to the invalidOrders. Instead, message2.xml should appear in the USA folder, and message4.xml should appear the GreatBritain folder.

Next steps

Next you will trace messages through your routing context to see where you can optimize and fine tune your routing context’s performance, as described in Chapter 7, To Trace a Message Through a Route.