Interactive written mini-course · Free public preview

WebhookLab

Learn webhook failure modes by doing.

Full-stack developers learning reliable event processing · Version 0.1.0 · Original examples

Lesson one — free preview

The complete local package has six written lessons. This public page provides one complete lesson and quiz. No video or certificate is implied.

1. One event, several deliveries

A delivery is an attempt to bring an event to your system. Retrying the same event should not repeat an external business action. Start by naming the event identity and the business effect separately. A sender delivery ID, business order ID and resource version can mean different things. In this exercise, event IDs and resource versions are deliberately synthetic. The guarded example keeps completed event IDs in memory. Run the same event twice and inspect the write count. That demonstrates a local pattern; it is not a durable production ledger.

Exercise

Replace the example with two identical deliveries of evt-A. Run both modes. Record why guarded mode writes once and naive mode writes twice.

Open HookReplay · Open ContractLens

Choose the most accurate statementTreat every HTTP delivery as a new business actionUse an event identity to detect replay while separately controlling the business effectDeduplicate only by the current display name

Use exercises as evidence of what you tried

Answers remain in memory until you close or clear the page. Exporting creates a local JSON record; it is not a credential or proof of production experience. The package includes a practical workbook and the related offline exercise pages.

Technical reference: Stripe webhook documentation. Provider rules differ; the examples use a synthetic version contract.

Keep the complete workflow.

Six short written lessons, synthetic exercises, quizzes with explanations and a downloadable progress record. The public preview includes lesson one.

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