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iSeries System Debugger Gets a Facelift

Did you know that the iSeries debug interface recently underwent a bit of a facelift? Rather than a green-screen interface, the system debugger now sports a new GUI.

With good performance and features such as an integrated call stack window, breakpoint groups, variable monitors and a local variables display, this interface has all of the functions developers have come to expect in state-of-the-art debuggers. Because it was designed to be a graphical interface to the iSeries system debugger APIs and isn't another debugger ported to these APIs, this new GUI interface can be used to debug practically any scenario that a developer could debug using the Integrated Language Environment* (ILE) green-screen interface without a paradigm shift.

Written in Java*, the graphical system debugger (see Figure 1) runs on most clients that support Java 1.3 or higher. It uses TCP/IP sockets to communicate with a server job to debug programs running on the iSeries server. It's available for OS/400* V5R1 via PTF.

Languages Supported
The new interface to the system debugger supports the following ILE languages:

  • ILE C/C++
  • ILE CL
  • Java

In addition some old program model (OPM) languages also can be debugged if the *SRCDBG or *LSTDBG option is used on the compile. The following OPM languages are supported:


(Note: To debug these languages using the Start Debug (STRDBG) command, use the OPMSRC(*YES) option.)

Design Goal
The first goal of building the new debugger was to provide a modern interface that's comparable with other debuggers on the market and could be used by practically every iSeries developer. To accomplish this, it was recognized that the new interface needed to support all debug scenarios supported by the green-screen interface. The graphical system debugger also would need to be usable from practically any client.

To achieve this goal, the new debugger was written in Java and supports several different startup modes. One mode allows users to register for debug on a particular system, such that when they issue the STRDBG command, the graphical system debugger appears on their client. This allows users to debug in almost any scenario that could be debugged using the green-screen interface to the system debugger. Even if developers have driver programs that issue a Start Server Job (STRSRVJOB) command followed by a STRDBG command, the developers can take advantage of this graphical debug interface without changing the driver program.

















This new GUI interface can be used to debug practically any scenario that a developer could debug using the Integrated Language Environment (ILE) green-screen interface without a paradigm shift.

Cary Bates is a senior software engineer with IBM. Cary can be reached at

Steve Halverson is an advisory software engineer IBM. He can be reached at



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