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Showing posts from 2016

Comment your data

I am a big believer in embedding comments in data files.

This has always served me well. I'm hoping this short essay will convince you to do the same.

Kinds of things you could write as comments Here is a short list of things that can 
Describe the data file layout and structureDescribe why the structure is what it isDescribe legal valuesDescribe what changes are allowedDescribe the history of changesDescribe what program uses this data fileDescribe assumptions about the data fileInclude the checksum or digital signature for the fileSeparate out clumps of records for readabilityComment out records with problemsDescribe what version of the data schema is in useInclude a URL to the descriptive wiki pageInclude a copyright or license
In many ways, this is similar to how JavaDocs is embedded in an application. The idea is to keep the documentation near the data, just like JavaDocs keeps the docs near the code.

Formats which allow comments
By the way, the demarcation betwe…

Microservice architectures and the IBM Mainframe - Recollections of similarity

As I learn about Docker, containerization, and micro-services, I can't help but think we've been down (part of) this road before.  Without a doubt, there's a lot of innovation in Docker, so don't misunderstand me.  However, I want to acknowledge the good parts of what I experienced long ago in my limited experience on IBM mainframes and perhaps there are some lessons to be learned here as well.

My experience on mainframes was using the IBM VM/ESA operating system from 1992-1994 at IBM's Boca Raton facility ("Home of the PC").  VM/ESA (now known as z/VM) is a (some would say "the") virtual machine operating system.  It has a history which is nearly as old as UNIX.

One thing you have to know about VM/ESA is that it divides a mainframe up into thousands of virtual machines, each of which runs a single user, single tasking operating system called CMS (conversational monitor system).  CMS is much like MSDOS (in my opinion).   As a result, it is a pr…