Monday, March 26, 2007

Mainframe productivity tools and source management


Most mainframe jobs require job-ready skills in the normal utilities that go with a mainframe environment. Usually these include TSO/ISPF and Roscoe, which tends to be implemented as an even simpler source manipulation tool using fewer resources for most tasks. Here is a reference on ISPF, and that would include a review of the PF and PA keys.

By the mid 1980s, 3270-type terminals had extensive programmability features including play-keys that could fill in log-on information and set up screens. These seem passe today.

REXX (the Restructured Extended Executor), as an interpretive language, is used in some TSO shops but I have never needed it. Here is the wiki write-up. TPX is often used as a session control and is sometimes used to manage complicated interrelated test and production versions of entities on different platforms (this can present issues of maintaining.

All shops use source control management and security products on the mainframe. The major source control packages are Serena’s Changeman, and CA-Endeavor and CA-Librarian. These products guarantee that source code and load modules remain “in sync”, an important security issue (especially for internal security). Since the late 1980s, programmers typically have not had access to update production files, with access controlled by products like Top-Secret and RACF. Some programmers find this annoying (and believe that programmers should be bonded); others find it reassuring. Some database products, such as IDMS central version or Dun and Bradstreet’s Information Expert, can be difficult to secure completely with these products.

CC/Harvest provides similar source control in a client-server environment, and I had some training in it in 2001.

Computer Associates, in one recent press release, makes the amazing statement that about 75% of the world's business systems are still in COBOL, at this link. CA also has a link discussing constructive legacy migration to client-server here. In the 1990s, companies sometimes kept original legacy systems and replicated the data on a mid-tier for a common user interface after mergers, but direct connect technologies (available from most RDB vendors like DB2 but not necessarily part of Ansi SQL) may be making this less appealing now.

A job that I had with a small consulting company in 1989 actually used VM on a 4341, with an operating system and F-disk that resembled the operation of a DOD PC at the time. You could access SAS directly from VM, or jump to an MVS environment on a 4381.

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