Pub/Sub

Lux supports Redis-compatible publish/subscribe messaging. Clients can subscribe to named channels or glob-style patterns, and any client can publish messages to a channel. Messages are delivered to all matching subscribers in realtime. Pub/Sub in Lux works with any existing Redis client library.

Subscribe to one or more named channels. The connection enters subscriber mode and will receive messages published to any of the subscribed channels.

SUBSCRIBE channel [channel ...]

127.0.0.1:6379> SUBSCRIBE notifications alerts
1) "subscribe"
2) "notifications"
3) (integer) 1
1) "subscribe"
2) "alerts"
3) (integer) 2

UNSUBSCRIBE

Unsubscribe from one or more channels. If called with no arguments, unsubscribes from all channels.

UNSUBSCRIBE [channel ...]

PSUBSCRIBE

Subscribe to channels matching one or more glob-style patterns. * matches any sequence of characters, ? matches a single character, and [abc] matches any character in the set.

PSUBSCRIBE pattern [pattern ...]

127.0.0.1:6379> PSUBSCRIBE events:*
1) "psubscribe"
2) "events:*"
3) (integer) 1

PUNSUBSCRIBE

Unsubscribe from one or more patterns. If called with no arguments, unsubscribes from all patterns.

PUNSUBSCRIBE [pattern ...]

PUBLISH

Publish a message to a channel. Returns the number of clients that received the message. This includes both clients subscribed directly to the channel via SUBSCRIBE and clients whose PSUBSCRIBE patterns match the channel name.

PUBLISH channel message

127.0.0.1:6379> PUBLISH notifications '{"type":"order","id":1234}'
(integer) 3

Message Formats

Messages arrive in different formats depending on whether the subscription was made with SUBSCRIBE or PSUBSCRIBE.

Channel subscription (SUBSCRIBE)

["message", channel, payload]

1) "message"
2) "notifications"
3) "{"type":"order","id":1234}"

Pattern subscription (PSUBSCRIBE)

["pmessage", pattern, channel, payload]

1) "pmessage"
2) "events:*"
3) "events:orders"
4) "{"type":"order","id":1234}"

Example: Basic Pub/Sub

A typical pattern uses two connections: one for subscribing and one for publishing. The subscriber connection enters a special mode where it can only receive messages and manage subscriptions.

Client A (subscriber)

127.0.0.1:6379> SUBSCRIBE chat:general
1) "subscribe"
2) "chat:general"
3) (integer) 1

... waiting for messages ...

1) "message"
2) "chat:general"
3) "hello from client B"

Client B (publisher)

127.0.0.1:6379> PUBLISH chat:general "hello from client B"
(integer) 1

KSUB vs Pub/Sub

Lux has two realtime messaging systems that complement each other. Choosing the right one depends on whether you are reacting to data changes or sending explicit messages.

	KSUB	Pub/Sub
Trigger	Implicit: fires on any key mutation (SET, HSET, DEL, etc.)	Explicit: only fires when a client calls PUBLISH
Payload	Pattern, key name, and operation type	Arbitrary message string
Best for	Reacting to state changes, cache invalidation, live dashboards	Chat, notifications, inter-service messaging, broadcasting
Data awareness	Knows which key changed and how	No awareness of stored data

Use KSUB when you want to be notified about data changes without modifying the code that writes the data. Use Pub/Sub when you need to send messages between clients that are not tied to key mutations.

Build on Lux without guessing.