Publishing Messages

To publish a message, choose the abstraction level that matches your application’s responsibility:

• [Reactive]ValkeyConnection is the low-level contract and operates on already-serialized (byte[]) channel and message data.
• [Reactive]ValkeyOperations (typically through ValkeyTemplate) publishes messages by using the template’s configured serializers for conversion.
• ValkeyMessageSendingTemplate integrates with Spring Messaging and delegates payload conversion to a MessageConverter, selecting converters according to the payload type and, if present, the contentType header.

The imperative API offers all three variants. The reactive API offers the low-level connection and ReactiveValkeyOperations variants.

The following table summarizes the differences between the sending options:

Variant	Responsibility	Conversion model
[Reactive]ValkeyConnection	Publish binary channel and message data.	Application code provides the binary (byte[]/ByteBuffer) values.
ValkeyTemplate / [Reactive]ValkeyOperations	Publish application values through the Valkey data access abstraction.	Uses the configured value serializer for the message body. Publication is therefore bound to the template-specific value serializer.
ValkeyMessageSendingTemplate	Publish through Spring’s Message<?> abstraction for flexible message conversion.	Uses ValkeyMessageConverters to select a MessageConverter according to the payload type and, if present, the MessageHeaders.CONTENT_TYPE header. Useful for applications that already use Spring Messaging or annotation-driven listeners.

The following example shows the available sending variants:

Imperative

// send message through connection
ValkeyConnection connection = …
byte[] channel = …
byte[] message = …
connection.pubSubCommands().publish(channel, message);

// send message through ValkeyOperations
ValkeyOperations<String, Object> operations = …
Long numberOfClients = operations.convertAndSend("chatroom", "hello!");

Reactive

// send message through connection
ReactiveValkeyConnection connection = …
ByteBuffer channel = …
ByteBuffer message = …
connection.pubSubCommands().publish(channel, message);

// send message through ReactiveValkeyOperations
ReactiveValkeyOperations<String, String> operations = …
Mono<Long> numberOfClients = operations.convertAndSend("chatroom", "hello!");

Spring Messaging

ValkeyMessageSendingTemplate template = …
template.convertAndSend("chatroom", new Greeting("hello", "world"));

template.convertAndSend("chatroom", new Greeting("hello", "world"),    // (1)
     Map.of(MessageHeaders.CONTENT_TYPE, "application/json"));

template.convertAndSend("chatroom", new Greeting("hello", "world"),    // (2)
     Map.of(MessageHeaders.CONTENT_TYPE, JdkSerializerMessageConverter.APPLICATION_JAVA_SERIALIZED_OBJECT_VALUE));

1. Provide a contentType as hint for converter selection. Valkey Pub/Sub does not support headers so it transmits only the serialized message.
2. Select Java Serialization for the message body. Requires JdkSerializerMessageConverter to use this content type.

Note: All three drivers (Valkey GLIDE, Lettuce, and Jedis) support publishing messages via Pub/Sub.