Tracing a distributed application

OLT creates a graphical trace of your distributed application. You can use this trace to analyze performance and isolate communication errors. In addition, you can set method breakpoints on the trace, prior to running OLT in conjunction with the debugger. Even if your ultimate goal is to debug your application, you should first create a trace by running OLT in trace only mode, then set method breakpoints and rerun OLT in trace and debug mode.

Your client application, application server, and OLT can be running on the same workstation or they can all run on different workstations. The instructions below apply to any configuration of the components involved.

On Solaris, only the OLT server is available. Traces can only be monitored from an AIX or Windows NT workstation.

To trace a distributed application, follow these steps:

  1. From a command line, enter olt. OLT is started..
    ngwin.gif (1069 bytes)On Windows NT, do not close the OLT command prompt window until you have finished tracing and debugging.
  2. Start your client application as follows:

    C++ client application:
    Start your C++ application from a command prompt.

    ngwin.gif (1069 bytes)If OLT is running on the same machine as your client , you can alternatively start the application by selecting File > Start process. The Start Process dialog box maintains a list of previously-run applications, making it easier to run your application a second time. If your client is running on a different workstation, you must start the client application from a command prompt, as explained in the topic "Tracing from a remote workstation".

    Java client application:
    At a command prompt, enter this command:

    java
    -Dcom.ibm.CORBA.BootstrapHost=<BootstrapHostname>
    -Dcom.ibm.CORBA.EnableApplicationOLT=true
    -Dcom.ibm.CORBA.OLTApplicationHost=<OLT_Server_Host>
    -Dcom.ibm.CORBA.OLTApplicationPort=<OLT_Server_Port>
    -DOLTClient=true
    yourapp

    where:
    <BootstrapHostname> = your fully-qualified server application host name (only needed if System Manager is running on a different host)
    <OLT_Server_Host> = the fully-qualified name or TCP/IP address of the machine running your OLT server
    <OLT_Server_Port> = the port where the OLT server listens for connecting OLT clients

  3. On the OLT viewer's Client Controller page, select the client id for the client application you started.
  4. Select Trace only from the list of execution modes.
  5. If you want all subsequent client applications registering with OLT to use the same settings, check the Use default settings for all clients box.

    If you do not check this box, a dialog box opens when the next client application attempts to register with OLT. To use the same settings, click Run. To change the settings for the application, click Change settings and do the following on the Client Controller page:

    1. Select the client id that corresponds to the client application you started.
    2. In the Debugger hostname field, enter the host name for the workstation on which you started the debugger daemon. If you changed the default port number for the Debugger Daemon (8001), enter the new port number in the Debugger TCP/IP port field.
    3. Select Trace only from the execution mode list. 
    4. Click Apply to apply the monitoring mode change.
  6. Click Apply to apply the monitoring mode change.
  7. Go to the OLT Trace page to start viewing the trace. 

As your client application, or servlet, makes calls to the application server (or multiple servers), trace lines and event symbols should appear in the OLT viewer. Once the application has finished running, you can use the trace to set method breakpoints on any debuggable events (debuggable events are represented by filled circles).

The OLT viewer can display a maximum of 300 trace lines (object instances).


Starting the OLT server and viewer on separate workstations
Setting method breakpoints on the trace
Navigating the trace

ngrelc.gif (533 bytes)
How to read the trace


OLT troubleshooting