System playground

What is happening

Pick a scenario and send a request — the packet travels through the city, and every step is explained here.

The animation is slowed down for clarity; latencies in the trace are realistic.

Request

GET/api/orders/42

Ctrl + Enter

Scenarios

01Synchronous requestClient → gateway → API → database → 200 response.02Cache miss and hitThe first request hits the database, the repeat is served from Redis.03Validation errorInvalid JSON stops at the API with a 422. Fix the body to get a 201.04Missing authA request without a token is rejected at the gateway with 401.05Rate limitEight requests in a row: five pass, the rest get 429 before the service.06Background jobThe API answers 202 right away; heavy work goes to a queue and a worker.07Retries with backoffThe external payment API fails; the worker retries with a growing delay.08Dead letter queueOut of attempts, the task lands in the DLQ and an alert fires.09Circuit breakerThe provider does not answer: after three timeouts the breaker opens and requests get a fast 503. Send several times in a row.10Idempotent webhookThe provider sends an event. The same id again is dropped as a repeat; a new id gets processed.11Fan-out: one event, three subscribersThe order publishes order.created to Kafka, and inventory, analytics and notifications read it, each on its own.12Chaos: a worker goes downAn import becomes a queue of jobs; one worker is down, the queue grows and the autoscaler brings a replacement.

Client → gateway → API → database → 200 response.

Trace

Send a request to see a span for every node.

Response

The response appears when the request is back at the client.

Logs

All quiet so far.

How a request travels through a system

Request

Trace

Response

Logs

System components