Card 09/ 10
Practice: A Style for Three Products
A two-person startup, a bank's payments platform and an image resizer.
Choosing a style from the team and the product is practised here on three briefs that look nothing alike. For each, choose a style, name the pressure that decided it, and name the main risk, before opening the answers.
The briefs.
- Two engineers are building a booking app for yoga studios. The product changes every week as they learn what studios want.
- A bank's payments platform is built by twelve teams: cards, transfers, fraud checks, statements and others. Each must release on its own schedule, and fraud checks must react to every payment.
- A photo site needs thumbnails made when users upload images. Uploads arrive in bursts in the evening, and almost none at night.
Check your answers
- A modular monolith. One small team and a product still changing shape: every change would cross service boundaries, and running services would eat the week. Risk: modules reaching into each other's tables, which makes a later split hard.
- Microservices, with events between them. Twelve teams need to release separately, and fraud checks, statements and notifications all react to each payment, which suits events. Risk: shared databases, and payments needing consistency across services, which needs sagas and careful tracing.
- A serverless function for the resizing. Short jobs, triggered by uploads, uneven through the day, idle at night. Risk: cold starts, which do not matter here because nobody waits on a thumbnail, and per-call cost if uploads became steady and heavy.
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