Tdf linked in


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Demonstration of MVS skill set involving cross memory server application

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Tdf linked in

  1. 1. Trap Diagnostic Facility (TDF)
  2. 2. TDF Methodology • Traditional Debuggers use recovery (ESTAEX or FRR) requiring the application to modify its recovery strategy • TDF uses the TRAP instruction and does not require modifications to application recovery strategy
  3. 3. TDF Methodoloy • One server required per LPAR and only one server can be active per LPAR • The server creates – System PC routines callable from any address space – Shared (64 bit) memory object for communication – API to connect/disconnect from debugging session
  4. 4. TDF User Interface In the following screen example, the TDF server has been started and a test program, job TDFHOOK and program TSTTDFHK has been started with a TDFHOOK call. In this example, the test program is selected to start a UI session.
  5. 5. TDF User Interface (UI) Flow When a suspended task is selected, •The TDF UI PCs to server to connect to the suspended task •TDF API connects the task so that no other UI can connect to it and replies with the current program state •TDF UI display the state as follows:
  6. 6. TDF User Interface (UI) From the initial connection state screen, you can issue such as a D command to display application storage
  7. 7. TDF User Interface • Large display requests (more data than can fit in a screen) are broken into multiple requests. • If an abend occurs, the request is ended • If any command is entered, the request is ended • At the end of a screen, if more data is required, press enter for the next screen until the request has completed
  8. 8. TDF User Interface You can also use the T command to step through program execution. The T display automatically shows the current program state. It highlights modifications to registers and branching instructions as follows:
  9. 9. TDF UI Methodology The final display mode is scrolling. In this mode, all command results are displayed in the sequence issued. The following screens demonstrate scrolling.
  10. 10. TDF UI Methodology You can terminate a UI session as follows: •Press PF3. The API disconnects the UI and places the application back in the suspended queue. •Enter the E command to disconnect and release the application. It will continue uninterrupted execution.
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