To download, install and run Redis please refer to the Redis documentation.

To begin interacting with Redis you first need to connect to it. Spring Integration uses support provided by another Spring project, Spring Data Redis, which provides typical Spring constructs: ConnectionFactory and Template. Those abstractions simplify integration with several Redis-client Java APIs. Currently Spring-Data-Redis supports jedis, jredis and rjc

RedisConnectionFactory

To connect to Redis you would use one of the implementations of the RedisConnectionFactory interface:

public interface RedisConnectionFactory extends PersistenceExceptionTranslator {

	/**
	 * Provides a suitable connection for interacting with Redis.
	 *
	 * @return connection for interacting with Redis.
	 */
	RedisConnection getConnection();
}

The example below shows how to create a JedisConnectionFactory.

In Java:

JedisConnectionFactory jcf = new JedisConnectionFactory();
jcf.afterPropertiesSet();

Or in Spring's XML configuration:

<bean id="redisConnectionFactory"
    class="o.s.data.redis.connection.jedis.JedisConnectionFactory">
    <property name="port" value="7379" />
</bean>

The implementations of RedisConnectionFactory provide a set of properties such as port and host that can be set if needed. Once an instance of RedisConnectionFactory is created, you can create an instance of RedisTemplate and inject it with the RedisConnectionFactory.

RedisTemplate

As with other template classes in Spring (e.g., JdbcTemplate, JmsTemplate) RedisTemplate is a helper class that simplifies Redis data access code. For more information about RedisTemplate and its variations (e.g., StringRedisTemplate) please refer to the Spring-Data-Redis documentation

The code below shows how to create an instance of RedisTemplate:

In Java:

RedisTemplate rt = new RedisTemplate<String, Object>();
rt.setConnectionFactory(redisConnectionFactory);

Or in Spring's XML configuration::

<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate">
	<property name="connectionFactory" ref="redisConnectionFactory"/>
</bean>

As mentioned in the introduction Redis provides support for Publish-Subscribe messaging via its PUBLISH, SUBSCRIBE and UNSUBSCRIBE commands. As with JMS and AMQP, Spring Integration provides Message Channels and adapters for sending and receiving messages via Redis.

<int-redis:publish-subscribe-channel id="redisChannel" topic-name="si.test.topic"/>

<int-redis:inbound-channel-adapter id="redisAdapter"
       topics="foo, bar"
       channel="receiveChannel"
       error-channel="testErrorChannel"
       message-converter="testConverter" />

<bean id="redisConnectionFactory"
    class="o.s.data.redis.connection.jedis.JedisConnectionFactory">
    <property name="port" value="7379" />
</bean>

<bean id="testConverter" class="foo.bar.SampleMessageConverter" />

<int-redis:outbound-channel-adapter id="outboundAdapter"
    channel="sendChannel"
    topic="foo"
    message-converter="testConverter"/>

<bean id="redisConnectionFactory"
    class="o.s.data.redis.connection.jedis.JedisConnectionFactory">
    <property name="port" value="7379"/>
</bean>

<bean id="testConverter" class="foo.bar.SampleMessageConverter" />

<int-redis:queue-inbound-channel-adapter id="" 
                    channel="" 
                    auto-startup="" 
                    phase="" 
                    connection-factory="" 
                    queue="" 
                    error-channel="" 
                    serializer="" 
                    receive-timeout="" 
                    recovery-interval="" 
                    expect-message="" 
                    task-executor=""/> 
		

<int-redis:queue-outbound-channel-adapter id="" 
                    channel="" 
                    connection-factory="" 
                    queue="" 
                    queue-expression="" 
                    serializer="" 
                    extract-payload="" />
			  

As described in EIP, a Message Store allows you to persist Messages. This can be very useful when dealing with components that have a capability to buffer messages (Aggregator, Resequencer, etc.) if reliability is a concern. In Spring Integration, the MessageStore strategy also provides the foundation for the ClaimCheck pattern, which is described in EIP as well.

Spring Integration's Redis module provides the RedisMessageStore.

<bean id="redisMessageStore" class="o.s.i.redis.store.RedisMessageStore">
    <constructor-arg ref="redisConnectionFactory"/>
</bean>

<int:aggregator input-channel="inputChannel" output-channel="outputChannel"
         message-store="redisMessageStore"/>

Above is a sample RedisMessageStore configuration that shows its usage by an Aggregator. As you can see it is a simple bean configuration, and it expects a RedisConnectionFactory as a constructor argument.

By default the RedisMessageStore will use Java serialization to serialize the Message. However if you want to use a different serialization technique (e.g., JSON), you can provide your own serializer via the valueSerializer property of the RedisMessageStore.

23.4.1 Redis Channel Message Stores

The RedisMessageStore above maintains each group as a value under a single key (the group id). While this can be used to back a QueueChannel for persistence, a specialized RedisChannelMessageStore is provided for that purpose (since version 4.0). This store uses a LIST for each channel and LPUSH when sending and RPOP when receiving messages. This store also uses JDK serialization by default, but the value serializer can be modified as described above.

It is recommended that this store is used for backing channels, instead of the general RedisMessageStore.

<bean id="redisMessageStore" class="o.s.i.redis.store.RedisChannelMessageStore">
	<constructor-arg ref="redisConnectionFactory"/>
</bean>

<int:channel id="somePersistentQueueChannel">
	<int:queue message-store="redisMessageStore"/>
<int:channel>

The keys that are used to store the data have the form <storeBeanName>:<channelId> (in the above example, redisMessageStore:somePersistentQueueChannel).

In addition, a subclass RedisChannelPriorityMessageStore is also provided. When this is used with a QueueChannel, the messages are received in (FIFO within) priority order. It uses the standard IntegrationMessageHeaderAccessor.PRIORITY header and supports priority values 0 - 9; messages with other priorities (and messages with no priority) are retrieved in FIFO order after any messages with priority.

	Important
	These stores implement only BasicMessageGroupStore and do not implement MessageGroupStore; they can only be used for situations such as backing a QueueChannel.

As of Spring Integration 3.0 a new Redis-based MetadataStore (Section 8.4, “Metadata Store”) implementation is available. The RedisMetadataStore can be used to maintain state of a MetadataStore across application restarts. This new MetadataStore implementation can be used with adapters such as:

In order to instruct these adapters to use the new RedisMetadataStore simply declare a Spring bean using the bean name metadataStore. The Twitter Inbound Channel Adapter and the Feed Inbound Channel Adapter will both automatically pick up and use the declared RedisMetadataStore.

<bean name="metadataStore" class="o.s.i.redis.store.metadata.RedisMetadataStore">
    <constructor-arg name="connectionFactory" ref="redisConnectionFactory"/>
</bean>

The RedisMetadataStore is backed by RedisProperties and interaction with it uses BoundHashOperations, which, in turn, requires a key for the entire Properties store. In the case of the MetadataStore, this key plays the role of a region, which is useful in distributed environment, when several applications use the same Redis server. By default this key has the value MetaData.

Starting with version 4.0, this store now implements ConcurrentMetadataStore, allowing it to be reliably shared across multiple application instances where only one instance will be allowed to store or modify a key's value.

The RedisStore Inbound Channel Adapter is a polling consumer that reads data from a Redis collection and sends it as a Message payload.

<int-redis:store-inbound-channel-adapter id="listAdapter"
    connection-factory="redisConnectionFactory"
    key="myCollection"
    channel="redisChannel"
    collection-type="LIST" >
    <int:poller fixed-rate="2000" max-messages-per-poll="10"/>
</int-redis:store-inbound-channel-adapter>

As you can see from the configuration above you configure a Redis Store Inbound Channel Adapter using the store-inbound-channel-adapter element, providing values for various attributes such as:

and other attributes that are common across all other inbound adapters (e.g., 'channel').

	Note
	You cannot set both redis-template and connection-factory.

Important

By default, the adapter uses a StringRedisTemplate; this uses StringRedisSerializers for keys, values, hash keys and hash values. If your Redis store contains objects that are serialized with other techniques, you must supply a RedisTemplate configured with appropriate serializers. For example, if the store is written to using a RedisStore Outbound Adapter that has its extract-payload-elements set to false, you must provide a RedisTemplate configured thus: <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"> <property name="connectionFactory" ref="redisConnectionFactory"/> <property name="keySerializer"> <bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/> </property> <property name="hashKeySerializer"> <bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/> </property> </bean> This uses String serializers for keys and hash keys and the default JDK Serialization serializers for values and hash values.

The example above is relatively simple and static since it has a literal value for the key. Sometimes, you may need to change the value of the key at runtime based on some condition. To do that, simply use key-expression instead, where the provided expression can be any valid SpEL expression.

Also, you may wish to perform some post-processing to the successfully processed data that was read from the Redis collection. For example; you may want to move or remove the value after its been processed. You can do this using the Transaction Synchronization feature that was added with Spring Integration 2.2.

<int-redis:store-inbound-channel-adapter id="zsetAdapterWithSingleScoreAndSynchronization"
        connection-factory="redisConnectionFactory"
        key-expression="'presidents'"
        channel="otherRedisChannel"
        auto-startup="false"
        collection-type="ZSET">
            <int:poller fixed-rate="1000" max-messages-per-poll="2">
                <int:transactional synchronization-factory="syncFactory"/>
            </int:poller>
</int-redis:store-inbound-channel-adapter>

<int:transaction-synchronization-factory id="syncFactory">
	<int:after-commit expression="payload.removeByScore(18, 18)"/>
</int:transaction-synchronization-factory>

<bean id="transactionManager" class="o.s.i.transaction.PseudoTransactionManager"/>

As you can see from the above all, you need to do is declare your poller to be transactional with a transactional element. This element can reference a real transaction manager (for example if some other part of your flow invokes JDBC). If you don't have a 'real' transaction, you can use a o.s.i.transaction.PseudoTransactionManager which is an implementation of Spring's PlatformTransactionManager and enables the use of the transaction synchronization features of the redis adapter when there is no actual transaction.

	Important
	This does NOT make the Redis activities themselves transactional, it simply allows the synchronization of actions to be taken before/after success (commit) or after failure (rollback).

Once your poller is transactional all you need to do is set an instance of the org.springframework.integration.transaction.TransactionSynchronizationFactory on the transactional element. TransactionSynchronizationFactory will create an instance of the TransactionSynchronization. For your convenience we've exposed a default SpEL-based TransactionSynchronizationFactory which allows you to configure SpEL expressions, with their execution being coordinated (synchronized) with a transaction. Expressions for before-commit, after-commit, and after-rollback are supported, together with a channel for each where the evaluation result (if any) will be sent. For each sub-element you can specify expression and/or channel attributes. If only the channel attribute is present the received Message will be sent there as part of the particular synchronization scenario. If only the expression attribute is present and the result of an expression is a non-Null value, a Message with the result as the payload will be generated and sent to a default channel (NullChannel) and will appear in the logs (DEBUG). If you want the evaluation result to go to a specific channel add a channel attribute. If the result of an expression is null or void, no Message will be generated.

For more information about transaction synchronization, see Section C.3, “Transaction Synchronization”.

The RedisStore Outbound Channel Adapter allows you to write a Message payload to a Redis collection

<int-redis:store-outbound-channel-adapter id="redisListAdapter"
          collection-type="LIST"
          channel="requestChannel"
          key="myCollection" />

As you can see from the configuration above, you configure a Redis Store Outbound Channel Adapter using the store-inbound-channel-adapter element, providing values for various attributes such as:

and other attributes that are common across all other inbound adapters (e.g., 'channel').

	Note
	You cannot set both redis-template and connection-factory.

Important

By default, the adapter uses a StringRedisTemplate; this uses StringRedisSerializers for keys, values, hash keys and hash values. However, if extract-payload-elements is set to false, a RedisTemplate using StringRedisSerializers for keys and hash keys, and JdkSerializationRedisSerializers for values and hash values will be used. With the JDK serializer, it is important to understand that java serialization is used for all values, regardless of whether the value is actually a collection or not. If you need more control over the serialization of values, you may want to consider providing your own RedisTemplate rather than relying upon these defaults.

The example above is relatively simple and static since it has a literal values for the key and other attributes. Sometimes you may need to change the values dynamically at runtime based on some condition. To do that simply use their -expression equivalents (key-expression, map-key-expression etc.) where the provided expression can be any valid SpEL expression.

Since Spring Integration 4.0, the Redis Command Gateway is available to perform any standard Redis command using generic RedisConnection#execute method:

<int-redis:outbound-gateway
		request-channel="" 
		reply-channel="" 
		requires-reply="" 
		reply-timeout="" 
		connection-factory="" 
		redis-template="" 
		arguments-serializer="" 
		command-expression="" 
		argument-expressions="" 
		use-command-variable="" 
		arguments-strategy="" />
			

The <int-redis:outbound-gateway> can be used as a common component to perform any desired Redis operation. For example to get incremented value from Redis Atomic Number:

<int-redis:outbound-gateway request-channel="requestChannel"
	reply-channel="replyChannel"
	command-expression="'INCR'"/>

where the Message payload should be a name of redisCounter, which may be provided by org.springframework.data.redis.support.atomic.RedisAtomicInteger bean definition.

The RedisConnection#execute has a generic Object as return type and real result depends on command type, for example MGET returns a List<byte[]>. For more information about commands, their arguments and result type see Redis Specification.

Starting with version 4.0, the RedisLockRegistry is available. Certain components (for example aggregator and resequencer) use a lock obtained from a LockRegistry instance to ensure that only one thread is manipulating a group at a time. The DefaultLockRegistry performs this function within a single component; you can now configure an external lock registry on these components. When used with a shared MessageGroupStore, the RedisLockRegistry can be use to provide this functionality across multiple application instances, such that only one instance can manipulate the group at a time.

When a lock is released by a local thread, another local thread will generally be able to acquire the lock immediately. If a lock is released by a thread using a different registry instance, it can take up to 100ms to acquire the lock.

To avoid "hung" locks (when a server fails), the locks in this registry are expired after a default 60 seconds, but this can be configured on the registry. Locks are normally held for a much smaller time.

Important

Because the keys can expire, an attempt to unlock an expired lock will result in an exception being thrown. However, be aware that the resources protected by such a lock may have been compromised so such exceptions should be considered severe. The expiry should be set at a large enough value to prevent this condition, while small enough that the lock can be recovered after a server failure in a reasonable amount of time.