abobov/wallet-challenge

Wallet microservice

WALLET MICROSERVICE

A simple wallet microservice running on the JVM that manages credit/debit transactions on behalf of players.

Implementation details

• Current balance stored in Player entity.
• No service to manage players. Player created on first transaction.
• Not existing player treat as a player with 0 current balance and no transactions.
• Optimistic locking with retry used to perform concurrent transactions.
• Additional header field could be used to do idempotent transactions (see requests example file). Idempotent keys are stored in memory, in production could be used more reliable storage.

Running microservice

To run microservice with disposable database:

./mvnw spring-boot:run

To run with persistent storage (will store database files in current directory):

./mvnw spring-boot:run -Dspring-boot.run.profiles=persist

API Endpoints

All URIs are relative to http://localhost:8080/

HTTP request	Description
GET /players/{player}	Get current balance per player.
GET /players/{player}/transactions	Get list of transaction per player.
POST /players/{player}/transactions	Add transaction per player.

Examples could be found in IntelliJ IDEA HTTP Client format file wallet-requests.http.

API models

Transaction

{
  "id": "transaction-id",
  "type": "Credit",
  "amount": 10
}

• id - any string representing transaction id
• type - transaction type string, one of: Credit, Debit
• amount - transaction amount, number >= 0

All fields are required.

Balance

{
  "currentBalance": 10
}

• currentBalance - player current balance, number >= 0