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Pub/Sub messaging in Redis

Pub/Sub messaging is a messaging pattern in Redis that allows multiple clients to communicate with each other through a central messaging system. In Pub/Sub, clients are divided into two categories: publishers and subscribers. Publishers send messages to channels, while subscribers receive messages from channels they have subscribed to.

Here's an example of how Pub/Sub messaging works in Redis:

  • A publisher sends a message to a channel:
perl
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PUBLISH my-channel "Hello, World!"
  • A subscriber subscribes to the same channel:
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SUBSCRIBE my-channel
  • The subscriber receives the message sent by the publisher:
python
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1) "message"
2) "my-channel"
3) "Hello, World!"

This shows that the subscriber has received the message "Hello, World!" from the channel "my-channel".

You can also have multiple subscribers on the same channel. In this case, each subscriber will receive a copy of the message when it is sent:

perl
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SUBSCRIBE my-channel
python
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1) "message"
2) "my-channel"
3) "Hello, World!"
python
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1) "message"
2) "my-channel"
3) "Hello, World!"

In addition to publishing and subscribing to channels, Redis also supports pattern-based subscriptions. A pattern-based subscription allows a subscriber to receive messages that match a specific pattern. For example, a subscriber could subscribe to all channels that start with "news." like this:

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PSUBSCRIBE news.*

Then, when a message is published to a channel that matches the pattern, the subscriber will receive the message:

python
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1) "pmessage"
2) "news.*"
3) "news.sports"
4) "Hello, Sports Fans!"

This shows that the subscriber has received the message "Hello, Sports Fans!" from the channel "news.sports", which matches the pattern "news.*".



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