Aspects, perspectives... viewpoints!

My first role in IBM was as a "Systems Engineer", responsible for designing, well in those days we called it configuring IBM's standard hardware and systems software to provide the performance, capacity needed by my clients' applications, while also ensuring their systems were secure and available when  needed; and not forgetting batch and backup and loads of other "systems management" stuff!

And of course all this 'kit" filled a machine room, with separate cabinets for disks, tapes, controllers and of course the "mainframe", all connected together at a "noticeable" (quick, byt not rhat quick) speed.

These concerns were so different from those of my previous role as an aerodynamisist, "simply" writing programs (we call them applications now) to do stuff, running on my self contained minicomputer in the corner of a lab.  Ah, my PDP/11, I remember it well...

These two perspectives of computer systems could not be more different!  As a systems engineer it was all about two things - "deciding on how much hardware was needed", and equally importantly "deciding WHERE to store stuff" - by which I mean which disks and tapes to use for storing software and data (oh the effort it took to ensure databases were spread out over the right disks to minimise data retrieval times, and to store "log files" away from "lock files"!).  But as a programmer, all I'd ever worried about was writing clean code that did what I wanted.

These are two wholely different but equally valid perspectives onto a computer based IT system - each from the viewpoint (ah ha!) of a different stakeholder:

•  The software engineer's perspective; focused on what things the system is doing - that from now on I'll call the Functional Viewpoint
• The system engineer's perspective; concentrating on how and where it's doing its thing - that I'll call the Operational Viewpoint.

I'll discuss the merits and objectives of these (and other) viewpoints onto the one system model later, but for the moment I simply want to say each is a perfectly valid stand point from which to view a model. While the functional viewpoint is clearly more abstract (it chooses to " hide" a lot stuff about where and how), it can be quite sufficient.  But the moment a sense of place enters into your thinking, the more concrete world of the operational aspect is vital.