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Redis Essentials

You're reading from   Redis Essentials Harness the power of Redis to integrate and manage your projects efficiently

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Product type Paperback
Published in Sep 2015
Publisher Packt
ISBN-13 9781784392451
Length 230 pages
Edition 1st Edition
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Tools
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Toc

Pub/Sub

Pub/Sub stands for Publish-Subscribe, which is a pattern where messages are not sent directly to specific receivers. Publishers send messages to channels, and subscribers receive these messages if they are listening to a given channel.

Redis supports the Pub/Sub pattern and provides commands to publish messages and subscribe to channels.

Here are some examples of Pub/Sub applications:

  • News and weather dashboards
  • Chat applications
  • Push notifications, such as subway delay alerts
  • Remote code execution, similar to what the SaltStack tool supports

The following examples implement a remote command execution system, where a command is sent to a channel and the server that is subscribed to that channel executes the command.

The command PUBLISH sends a message to the Redis channel, and it returns the number of clients that received that message. A message gets lost if there are no clients subscribed to the channel when it comes in.

Create a file called publisher.js in the chapter 4 folder and save...

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