order-saga GitHub

Three services, one order, no oversell.

A SAGA over Kafka keeps stock, payment and order status consistent.

Each service owns its own Postgres. If payment fails, the order rolls back and its stock is released. Verified on AWS EC2.

Team project with Harsh Kokcha. Akshit built the auction service.

Read the code Run it
The auction page: alice won a Leica M6 at $31.00, and a tracker shows her order moving from won at auction to completed
The auction front end: a won auction becomes an order.

Every event, every stop.

Seven Kafka topics carry an order between services. Three of them undo work.

TopicFromToResult
auction-wonauctionorderOrder created
order-createdorderinventoryPending
inventory-reservedinventorypaymentStock reserved
payment-confirmedpaymentorderCompleted
inventory-rejectedinventoryorderRejected
payment-rejectedpaymentorderRolled back
order-rolled-backorderinventoryStock released

A message that fails 3 times goes to its .DLT topic instead of blocking the partition.

Measured under load.

A Redis lock per product; version checks and retries for payments and bids.

  • 10of 50

    Reservations won

    50 at once for 10 units. 40 rejected, none oversold.

  • 0failed

    Of 8,487 requests

    k6, 20 to 50 users: p95 136.68 ms, p99 202.96 ms, 169.6 req/s.

  • 379retried

    Bid conflicts

    1,000 bids, 32 threads, one auction. A replay gives the same price.

From a winning bid to a paid order.

The auction service hands its winner to the same SAGA as any order.

  1. 1

    Bid

    Proxy bidding: the leader pays one increment over the second-highest maximum.

  2. 2

    Close

    The close uses the same version check, so no last bid is lost.

  3. 3

    Hand off

    An outbox re-sends the win; the key auction-{id} makes one order.

  4. 4

    Pay

    Stock, then payment; a buyer who cannot pay rolls back.

What the first full run broke.

Five bugs, all fixed.

FoundFix
Images would not build on Apple SiliconMulti-arch base image
Postgres skipped the init scriptExecutable bit recorded in git
SAGA stalled for about 5 minutesTopics created with 3 partitions before services start
A fast payment arrived before its stock eventPending may go straight to Completed
A Completed order reverted@Version on the order; the loser retries

Run it.

52 tests need no Docker. The end-to-end script needs the stack up and ready.

Full setup 
git clone https://github.com/akshit9162/Distributed-Order-System
cd Distributed-Order-System
# 31 + 11 tests
(cd auction-service && mvn test)
(cd order-service && mvn test)
# 10 front-end tests
cd auction-service/frontend
npm ci && npm test && cd ../..
# Alice pays; Bob is rolled back
docker compose up -d
until curl -sf localhost:8084/ >/dev/null; do sleep 5; done
scripts/e2e-auctions.sh