Writing
Notes from inside billing systems, telephony stacks and execution platforms. Mostly the things I could not find written down when I needed them. RSS.
Telecom billing
Migrating a fixed-line billing system without losing a single CDR
· 9 min read
The hard part of a billing migration is not rating calls correctly in the new system. It is proving that both systems agree before you cut over, and still being able to reproduce last March a year afterwards.
Delivery
The website was the easy part
· 9 min read
Five weeks, one person, 48,000 lines. A therapy practice needed booking, a client area, session packages, debt tracking and four messaging transports. The hard parts were the ones I already knew from telecom billing.
Trading systems
Fifteen ideas, zero orders: how to kill your own hypothesis cheaply
· 7 min read
I built a trading platform before checking whether anything profitable would flow through it. Then I built the discipline that answered that question for fifteen strategies in a row, and never placed a single order.
Systems design
Designing systems that handle money: an invariant checklist
· 9 min read
The ten questions I settle before writing any code that moves money, and what breaks in each system where somebody left the answer implicit.
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Notes from inside these systems
Occasional write-ups on billing, telephony and execution latency: the parts the vendor documentation leaves out. A few emails a year, no marketing.