Implementing API Idempotency in SpringBoot Using Redis Token Mechanism

Idempotency is a concept where multiple identical requests have the same effect as a single request, crucial for preventing duplicate operations in distributed systems.

The article explains the definition of idempotency, its importance for API design, and the impact of introducing idempotency on system complexity.

It lists HTTP methods that are idempotent and presents four common implementation strategies: database unique primary key, optimistic lock, anti‑repeat token stored in Redis, and downstream unique sequence number.

For each strategy the applicable operations and constraints are described.

A concrete SpringBoot example demonstrates the anti‑repeat token approach: Maven dependencies are shown, Redis connection parameters are configured, a TokenUtilService class creates and validates tokens using Lua scripts, a TokenController exposes endpoints to obtain a token and test idempotent calls, the Application class starts the service, and a JUnit test verifies that the first call succeeds while subsequent calls are rejected.

Example Maven snippet: <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.3.4.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </dependency> </dependencies> </project>

Redis configuration example: spring: redis: ssl: false host: 127.0.0.1 port: 6379 database: 0 timeout: 1000 lettuce: pool: max-active: 100 max-wait: -1 min-idle: 0 max-idle: 20

Key Java classes are provided in the article, and the final section summarizes recommendations for choosing the appropriate idempotency method based on business scenarios.