Ebook · PDF, 23 pages
The bugs that hurt a point of sale never show up in a demo
A double charge on bad Wi-Fi. A sale saved without its payment. Two tills selling the last unit. Receipt numbers with gaps. This guide shows how Tilly POS designs each of them out, with the real ASP.NET Core and SQL Server code.
What’s inside
What the ebook covers
- The double charge: idempotency keys enforced by a unique index
- Half a sale: one transaction, and receipt numbers with no gaps
- The last unit: a conditional, row-locked UPDATE instead of check-then-write
- Stock as a ledger, with weighted-average cost in one SQL statement
- Multi-tenancy: EF Core query filters that default to nothing
- Sign-in: short JWTs, rotating hashed refresh tokens and reuse detection
- Permissions: without privilege escalation
- Audit: a log nobody can edit, not even the owner
- Billing webhooks: signed, time-limited and de-duplicated
- Shipping it: tests against a real SQL Server, Docker, health checks, backups and a one-page checklist
Screens
What you get
Read how it works first. Free excerpt: gap-free invoice numbers in SQL Server ↗, a free article on dev.to.
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