CODEWITHSUNDEEP
redispublish-subscribe
stojanman
stojanman

Reputation: 335

Redis Pub/Sub Usefulness?

I have a question that is bugging me quite heavily. What is the Redis pub/sub feature actually used for? I can only think of inter-process communication over TCP (either locally or distributed), however not much else.

Can someone please prove me wrong.

Upvotes: 6

Views: 3867

Answers (2)

abhiteki
abhiteki

Reputation: 53

a real use case in my experience. Lets say you have a web application deployed on 4 different servers(nodes,virtual machines) mostly on your virtual private cloud.

The web application maintains an in memory java map for its static data cache which occasionally changes .

Now every time the data changes in your database you would need all your servers to update there own in memory caches,this is the problem.

one way is to maintain all the static data in redis or any other cache on a separate server and the cache updates based on a scheduler.But here to access the static content which occasionally changes you need a scheduler and a separate cache server like redis or memcached etc. and each server points to this external cache.

Using pubsub of redis here: all servers subscribe to redis channel and if redis publishes the message when ever there is an update,addition,deletion of the data as a message to all of its subscribers.On receiving the message object and its type of update(ADD,REMOVED,UPDATED) each server updates its in memory static data map.

Upvotes: 3

Joshua Martell
Joshua Martell

Reputation: 7202

It's an easy way to plug into an event stream, generally between processes or machines. For instance, an user creates a published event. One process handles updating the database from the event, another updates user stats, another global stats, another updates the text search database, etc. They're all loosely coupled by subscribing to the channel. You can add new processes for testing updates and monitoring the system. It's a little different from a message queue in that there's no storing messages until they're processed, but Redis has other structures for those sorts of jobs.

Upvotes: 8

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