Structure & Behavior

Software creates value 2 ways:

• What it does today

• What all new things we can make it do tomorrow

"What it does today" is the system's behavior--calculating payroll, sending dropship orders, notifying friends. (And yes, all software systems are socio-technical systems & we won't be designing the socio- part of it just yet.)

Behavior can be characterized various ways:* Input/output pairs--this many hours at this pay rate in this jurisdiction should result in a paycheck like this & a tax filing like that.* Invariants--the sum of all entitlements should equal the sum of all deductions.
Behavior creates value. Rather than have to calculate a bunch of numbers by hand, the computer can calculate millions of them every second. Turns out people will pay not to have to calculate numbers by hand. If running the software costs $1 in electricity & you can charge folks $10 to run it on their behalf, then you have a business.

In theory, this business could run forever producing $10 out for every dollar we put in. We know this is an over-simplification. Bit rot is real. Something is always changing. Staying in place in the river requires constant paddling. But for purposes of the distinction I'm drawing, this is good enough for the moment.

You know what's better than a machine that spits out $10 for every $1 you put in?