PL/DS(ID:7473/)

PL/I for distributed systems 

Programming Language for Distributed Systems
References:
  • Zingaretti, D.P. "Porting DPPX from the IBM 8100 to the IBM ES/9370: installation and testing" IBM Systems Journal January 1990 view details Abstract: This paper describes the software tools, testing activities, and testing methods that were used to port the DPPX/SP operating system from its original implementation on the IBM 8100 Information System to its new implementation on the IBM ES-9370 Information System. Extract: Introduction
    Porting DPPX from the IBM8100 to the IBM ES/9370: Installation and testing This paper describes the software tools, testing activities, and testing methods that were used to port the DPPX/SP operating system from its original implementation on the IBM 8100 Information System to its new implementation on the IBM ES/9370 Information System.

    The porting of the distributed Processing Programming Executive System Product (DPPX/SP) operating system, which was originally designed to run on the IBM 8100 Information System, to the DPPX/370 operating system which runs on IBM ES/9370 hardware, moved an operating system from one hardware architecture to another.

    To accomplish the port, four basic steps had to be completed:

    1. A new compiler, the PL/DS2 compiler, had to be developed to generate System/370 Assembler instructions from PL/DS (Programming Language for Distributed Systems) source code.

    2. the machine-dependent components of the DPPX operating system had to be redesigned and rewritten to accommodate the new hardware.

    3. The machine-independent components of DPPX had to be recompiled with the new compiler.

    4. The new machine-dependent components and the recompiled machine-independent components had to be installed and tested on the ES/9370 hardware.

    These four steps took approximately 30 months to complete, with the most time spent on installing and testing the new recompiled components.

    Much attention was given to the testing effort of porting DPPX because of the unique problem that testing had to address: How to take the redesigned machine-dependent components of DPPX, mix them with the recompiled components, install them and test them on ES/9370 hardware, and assure that DPPX/370 running on an ES/9370 would work with a quality rating equal to, or better than, DPPX/SP running on an 8100.

    The solution was to divide the project into stages, start at the bottom, work to the top, and test it along the way.

    Extract: Summary
    Summary

    The development approach taken by the Distributed Systems Programming (DSP) organization was key to the successful port of DPPX/SP to DPPX/370 for many reasons. Programmer productivity was optimized by staging the development activities, by having a test bed before the actual hardware was available, and by providing the developers with tools to simplify debugging. A stable DPPX/370 system was attained very early in the development cycle by testing DPPX/370 at every stage rather than waiting for all development activity to complete. The component tests were executed by testers other than the component developers. This exposed documentation and usability problems, in addition to functional errors, which otherwise may not be have been found. The use of customer application environments in system test permitted greater and more realistic test coverage and required fewer resources than normal.

    The DSP organization is continually investigating new ways to improve its approach to systems development.