Client-Server – The Birth of Distributed Computing

In The Evolution of Enterprise IT  I described how what had been known as MIS became Enterprise IT.  The catalyst for this change was when the personal computer replaced dumb terminals on enterprise desktops.  Subsequent steps along the evolutionary cycle would require a stable foundation upon which to build new and exciting applications that moved further and further away from the mainframe in the glass house.

The key components include:

  • Hardware Infrastructure & Networks
  • Software Development Tools & Platforms

PC’s running DOS and connected to the mainframe via IRMA cards and coax cables had been in place for years.  It wasn’t until ethernet cables, routers, switches, etc. were in place that the PC could truly be considered “connected”.  It wasn’t until Windows 3.1 came along and tools like Powerbuilder became available that programmers could start developing client-server applications.  When these key components came together it changed the course of enterprise computing.  It also introduced a whole new set of challenges.

Prior to the on-set of client-server computing IBM mainframes absolutely dominated the enterprise.  Since the mainframe was the system any unplanned outages brought company productivity to a screeching halt.  IBM developed very sophisticated systems for applying software patches and fixing bugs that allowed guys like me to spend weekends updating the mainframe software while the rest of the company was actually enjoying their weekends.  While applying software updates to mainframes took a great deal of planning the process worked extraordinarily well.

90’s Hub and Spoke Client-Server Architecture

As client-server computing grew it became apparent that it was much more difficult to manage operating system software and applications across hundreds of PCs.  With mainframe you had one central location to update and apply changes.  In this new world the IT people had to go from one PC to the next with large stacks of diskettes to get everyone up to the same level of Microsoft Windows or Novell network drivers.  We jokingly referred to this as “sneakernet”, and this was long before you could actually wear sneakers to work.

In time tools became available to manage the deployment of software updates across the network and establish manageable virtual runtime environments (ala mainframe) that were manageable from…wait for it…within the glass house.

And so it went until…

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