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REDIS.md

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Redis

Redis can be used as a cache as well as a session store for a Spring Boot applications. As a cache, Redis is used to store the results of queries to the database. This reduces the number of queries to the database and improves performance. As a session store, Redis is used to store the session information for a web application.

Pom.xml Dependencies

Add the following dependencies to the pom.xml file to configure Redis for the Contoso Fiber application.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-cache</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-redis<artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.session</groupId>
	<artifactId>spring-session-data-redis</artifactId>
</dependency>

Caching with Redis - Spring Boot Configuration

To enable caching, we need to

  1. Enable caching in the application with the @EnableCaching annotation
  2. Configure the Redis cache manager
  3. Configure the connection to Redis from the application
  4. Use the @Cacheable annotation on the methods that we want to cache

Enable Caching

In the main application src/contoso-fiber/src/main/java/com/contoso/cams/CamsApplication.java, add the @EnableCaching annotation to the CamsApplication class.

@SpringBootApplication
@EnableCaching
public class ContosoFiberApplication {
    public static void main(String[] args) {
        SpringApplication.run(ContosoFiberApplication.class, args);
    }
}

Configure Redis Cache Manager

We will configure the Cache Manager with a bean in the src/contoso-fiber/src/main/java/com/contoso/cams/config/RedisCacheConfig.java file.

@Configuration
public class RedisCacheConfig {

    @Bean
    public RedisCacheConfiguration cacheConfiguration() {
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()
        .prefixCacheNameWith("com.contoso.cams.")
        .entryTtl(Duration.ofMinutes(60))
        .disableCachingNullValues()
        .serializeValuesWith(SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()));
        return config;
    }
    
    @Bean
    public RedisCacheManager cacheManager(RedisCacheConfiguration config, RedisConnectionFactory connectionFactory) {
        return RedisCacheManager.builder(connectionFactory)
            .cacheDefaults(config)
            .build();
    }
}

Configure the Connection to Redis

Spring Data Redis properties come from the application.properties file. The following properties are used to configure the connection to Redis.

spring.data.redis.host=localhost
spring.data.redis.port=6379

Use the @Cacheable Annotation

The @Cacheable annotation is used to cache the results of a method. The @Cacheable annotation will be used on the getAccount method in the AccountService class. The @CachePut annotation will be used on the updateAccount method in the AccountService class. You can use the @CacheEvict annotation to remove an item from the cache.

package com.contoso.cams.account;

@Service
@CacheConfig(cacheNames={"accounts"})
public class AccountService {
    @CachePut(value="account-details", key="#accountDetail.accountId")
    public AccountDetail updateAccount(AccountDetail accountDetail) {
    }

    @CachePut(value="account-details", key="#id")
    public AccountDetail setActive(Long id, boolean isActive) {
    }

    @Cacheable(value="account-details", key="#id")
    public AccountDetail getAccountDetail(Long id) {
    }
}

Session Management

In Contoso Fiber CAMS, Redis is used to store Spring Session that is used to manage the session information for a web application. In a Spring Boot application, Spring Session is configured with the spring-session-data-redis dependency in the pom.xml file.

<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-data-redis</artifactId>
</dependency>

Spring Session Configuration

To enable Spring Session, add the following properties to the application.properties file.

# Spring Session to leverage Redis to back a web application’s HttpSession
spring.session.redis.flush-mode=on-save
spring.session.redis.namespace=spring:session

Running the Application

Now that we have configured the application to use Redis, we can run the application and see the results in Redis. Click on an account and then go to the Redis CLI to see the results. Our keys have the prefix com.contoso.cams.

docker exec -it contoso_fiber_redis bash
root@redis:/data# redis-cli

127.0.0.1:6379> keys *
1) "com.contoso.cams.account-details::1"
2) "spring:session:sessions:05625b53-9a7e-4a01-bd97-8995fc902060"

Get the account details from Redis.

127.0.0.1:6379> get com.contoso.cams.account-details::1
"{\"@class\":\"com.contoso.cams.account.AccountDetail\",\"accountId\":1,\"customerId\":1,\"address\":\"123 Main St.\",\"city\":\"Burlington\",\"customerFirstName\":\"Nick\",\"customerLastName\":\"Dalalelis\",\"customerEmail\":\"[email protected]\",\"customerPhoneNumber\":\"617-528-5544\",\"selectedServicePlanId\":1,\"active\":false,\"supportCases\":[\"java.util.ArrayList\",[]]}"