A data warehouse preserves data.
It can be argued that a data warehouse preserves only data. This, however, is false.
To an extent, a data warehouse must also preserve processing details.
Indeed, a data warehouse exemplifies knowledge capture because the data and its processing steps are both captured.
The ETL …
more ...No discussion of legacy preservation is complete without some "Paving the Cowpaths" stories.
The phrase refers to the way cows tend to meander across the landscape in a remarkably consistent way. The cows reliably follow a consistent path. The paths tend to wander in ways that seem crazy to us …
It's 1980-something. We're working on a fairly complex system that includes some big machines and three computers. One of the computers has a magnetic tape drive into which it writes a log of interesting events. In the 80's, this was a pretty big deal.
An operational run will produce a …
Let's visit some other conversion activities in the 1970's. The gig was at a company implementing a customized insurance application. The actuaries used a PDP-10 (and Fortran) to compute their various tables and summaries.
I was roped into rewriting an actuarial Fortran programs into PL/1 for an IBM 370 …
Wind back the clock to the late 1970's. Yes, there were computers in those days.
Some of my earliest billable gigs where conversions from old OS to new OS. (Specifically DOS/VSE to OS/370, now called Z/OS.) Back when a company owned exactly one computer, all of the …
This is important:
Rule One: Writing Software is Capturing Knowledge.
Consequence: Converting Software is Preserving Knowledge.
When software is revised for a new framework or operating system or database or when an algorithm is converted to a new language, then we're "converting" (or "migrating") software. We're preserving code, and preserving …
more ...Step 1. Look at the original HamCalc. Even if you aren't interested in Ham radio, it's an epic, evolving achievement in a specialized kind of engineering support. It's a repository of mountains of mathematical models, some published by the ARRL, others scattered around the internet.
Step 2. Look closely at …
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