Mainframe Data in a Non-Mainframe World
Wednesday, December 14, 2016
by Taras Ciuriak
Modernisation, by its very nature, implies taking something old and applying new ideas to improve it. When we talk about modernisation in a computing context, we need to think about how modern technology can play nicely with data coming from older platforms.
Data Archaeology has been described as “the art and science of recovering computer data encoded and/or encrypted in now obsolete media or formats.” Of course, the mainframe is not obsolete, but in a Windows or Linux-centric world, mainframe data formats are best described as esoteric.
These data formats have evolved over time, along with the machinery they were meant to drive. But in many cases, there are no true analogues to those technologies in the open systems world.
For example, consider the Job Control Language (JCL) that you edit while logged into a mainframe Time Sharing Option (TSO) session. You are likely running the Interactive System Productivity Facility (ISPF) product on a software emulator of a 3270-type terminal. This modern scenario represents an evolution of the original mainframe environment.
Set your Wayback machines…
All of the tasks described above were previously done via a physical typewriter, attached to a card punch machine that knocked holes in a paper card.
Each line of a JCL “deck” in ISPF used to be a physical paper card. By punching holes in the card with a card punch, you would be editing a line of JCL. The cards would then be sorted into the correct order and placed on a card reader, which would read the deck of cards optically and convert them into bits in memory. This reader would then submit the JCL to the Job Entry Subsystem (JES) for execution.
The output from these jobs would then normally be printed on impact printers. Since memory and disk were extremely scarce and expensive, all efforts were taken to condense the data being printed. For example, eliminating white space wherever possible was a common method to compress report data. In order to control line spacing, therefore, a physical piece of tape called the carriage control tape was inserted into the printer. The printer would read the first character of each line and reference the tape to determine how many, if any, lines to skip before or after printing a line of data.
As the modern version of 3270-type terminal technology, ISPF, and laser printing came into being, the original technology adapted. The carriage control evolved to become the Forms Control Buffer (FCB), which replaced a physical tape with a file that described how to space lines. This allowed laser printers to support code written to print on older impact devices.
New software technologies like Advanced Function Presentation (AFP) were introduced by IBM to take advantage of these improvements and added the ability to manage graphics and fonts and create vastly more complex documents. These innovations laid the foundation for the modern graphics-rich account statements you receive in the mail from your bank or phone company to this day.
Modernisation and printing
When we think of modernisation today in an IT framework, we think of converting older COBOL and PL/I code to run on Windows or Linux machines. In the vast majority of cases, those programs were designed to generate output meant to be processed in a mainframe environment where carriage control and FCBs matter. The data would also have a record format meaning that each report’s records could be of fixed or variable length.
The output may be designed with an AFP PAGEDEF/FORMDEF in mind to format the data into a graphically-rich AFP data stream. Or the program may insert Xerox Dynamic Job Descriptor Entry (DJDE) statements meant to be interpreted in order to load FORMs and perform other specific functions at the print device.
For your modernisation plans to succeed, you need to ensure that this type of data is handled correctly going forward and LRS can help in this regard.
With software such as the VPSX/MFI (Micro Focus Interface) solution, LRS can process the data coming out of your Micro Focus environment. This ensures that the mainframe-formatted data is correctly handled when sent to modern networked printers via the VPSX solution.
Similarly, LRS Transforms can convert your AFP or LCDS/DJDE data into PDF for online viewing in a PageCenterX browser or a modern page description language such as Printer Command Language (PCL) or PostScript for delivery to modern printers.
With LRS, your modernised data can play nicely with the Windows or Linux platforms that power your business today and in the future. We have the products to simplify the modernisation process, and — just as importantly — a deep understanding of both modern and legacy technologies.