Book Image

Redis Essentials

Book Image

Redis Essentials

Overview of this book

Redis is the most popular in-memory key-value data store. It's very lightweight and its data types give it an edge over the other competitors. If you need an in-memory database or a high-performance cache system that is simple to use and highly scalable, Redis is what you need. Redis Essentials is a fast-paced guide that teaches the fundamentals on data types, explains how to manage data through commands, and shares experiences from big players in the industry. We start off by explaining the basics of Redis followed by the various data types such as Strings, hashes, lists, and more. Next, Common pitfalls for various scenarios are described, followed by solutions to ensure you do not fall into common traps. After this, major differences between client implementations in PHP, Python, and Ruby are presented. Next, you will learn how to extend Redis with Lua, get to know security techniques such as basic authorization, firewall rules, and SSL encryption, and discover how to use Twemproxy, Redis Sentinel, and Redis Cluster to scale infrastructures horizontally. At the end of this book, you will be able to utilize all the essential features of Redis to optimize your project's performance.
Table of Contents (17 chapters)
Redis Essentials
Credits
About the Authors
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
5
Clients for Your Favorite Language (Become a Redis Polyglot)
Index

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...