Category:Debugger Home

This is a master category and page for all things Debugger (Janus/TN3270 Sirius Debugger). It is currently under construction, so it is subject to changes and formatting.

About the Debuggers

The Janus Debugger is a tool designed for developers who create and maintain Janus Web Server applications. With software installed in the Model 204 Online, as well as on a workstation with a browser that can access the Web Server, the Janus Debugger lets you examine in statement by statement detail the SOUL code that the Web Server executes.

The TN3270 Debugger is designed for developers who create and maintain Model 204 3270 and Batch2 applications. With software installed on the Model 204 Online, it uses  the same Debugger Client as the Janus Debugger, letting you examine 3270 and Batch2 applications.

An instance of the Debugger Client can be debugging a web application (acting as the Janus Debugger), or it can be debugging a 3270 or Batch2 application (acting as the TN3270 Debugger). At any given time, it may only be debugging one type of application. The title bar of the Debugger Client indicates the application type.

These subsections continue the overview of the Debuggers:

The basic operation

When you are running under the Janus Debugger, and Janus Web Server is about to run a request on your behalf, or you are running under the TN3270 Debugger, and you run a 3270 or Batch2 request:

1. Request source code is sent to the Debugger Client deployed on a workstation.
2. The Debugger Client displays the code, navigable to top and bottom, with search features available.
3. Program execution is paused, the Debugger awaiting the instructions you provide through the Client GUI.

The feature set

Both Debuggers provide these typical debugging capabilities:

• Viewing code while running it
• Stepping through the code one statement at a time
• Examining variable values
• Using a separate "watch window" for the display of specified data items
• Setting breakpoints at which code execution pauses
• Skipping over selected subroutines/methods

In addition, the Debuggers provide:

• A compact Graphical User Interface with user configurable buttons and hot keys
• Views of the Model 204 audit trail and code executed by daemons
• Tracing of statements that modify variables in executed code lines, or tracing until a variable becomes a certain value
• Saving of sets of variables to be watched, which are restorable at any time
• Display of Web Server output (Janus Debugger) and screen variables (TN3270 Debugger)
• A code line's Model 204 procedure details (subsystem, file, name, line number, text preceding dummy string substitution)
• Filtering of program code to skip over all but the Model 204 procedure you identify or the procedures you selected (added to "White List")
• Stepping out of a called subroutine, method, or daemon and continuing processing at the statement after the call to the subroutine, method, or daemon
• Examination of longstrings, $lists, objects
• System class methods that let you insert code in User Language that runs only under the Debuggers

The architecture

The following figure displays the principal components in a Janus Debugger configuration:

The main components in a TN3270 Debugger configuration parallel those in the Janus Debugger configuration, the principal exception being the absence of the web browser:

Per Debugger session for a Janus Web or 3270 or Batch2 application, these components are active in the Online and on the workstation:

Versions and builds 

Independent of the version of Model 204 being run, the Debugger Client has its own numbered sequence of "builds" that contain new and updated features. From build to build of the Debugger Client, the About box (accessed by the Help menu) provides a searchable list of the principal changes in each of the previous builds of the Debugger Client.

System requirements

The Online Configuration section of this document specifies the requirements for Model 204 product release levels, licenses, and maintenance, as well as Debugger product authorization. In addition are instructions for configuring a Model 204 Online that hosts the Debugger, which include User 0 parameter and TCP port definitions and increases in storage table and work area sizes for both of these:

• The worker thread that services a debugging session
• The thread on which the program to be debugged is running  

Known limitations 

The following are known limitations and issues concerning the Janus and TN3270 Debuggers:

• You may not use either Debugger for DBCS data.  
• You may use the Janus Debugger on a Janus Web Legacy Support thread only if you also have a license for the TN3270 Debugger.
• No asynchronous daemon or $COMMBG requests may be debugged. They are simply ignored by the Debugger (and they execute normally).
• The client requires Windows 7 or higher.
• Both the Execution Trace tab (output from one trace) and the Web Buffer tab have 5000 line capacities. If the capacity is exceeded, the last 5000 lines are shown.