Redis pub-sub vs Kafka? What to use for a chat application?

This video is about a specific question around System design of a chat application, which generally remains un-addressed unless you actually have a design discussion. The question is : In the publisher subscriber section, why did we use Redis? Why not Kafka? The short answer is : Redis is the right choice for the use case of real time chat application. There are 4 reasons 1. SPEED Redis is in-memory , so it is faster. Where was Kafka has to make disk operations. 2. STORAGE REQUIREMENT Redis does not store messages , they just pass through to all the consumers  So, you only need to increase the processing and not the storage. Where-as in Kafka you need both compute and storage. 3. COST OF CREATING A TOPIC Kafka: Has extra cost because the partition needs to be created in all the Redis:  no cost of creating a new channel.  In fact no channel is created, you just send a message to a channel and you are good.  4. COST OF DELETING TOPIC  Deleting a topic in Kafka is not straight forward. Sometimes, delete topic operation takes long time and then you have to manually delete the topics from server. COMMANDS Redis: You can install Redis on local by following this instruction: https://redis.io/docs/getting-started/installation/ Start redis server: redis-server connect to redis server: redis-cli subscribe channel: SUBSCRIBE channel publish command: PUBLISH channel1 "hey" Observation : fast message sending and receive Kafka go to kafka folder downloaded from apache Kafka website: https://kafka.apache.org/downloads start zookeeper: bin/zookeeper-server-start.sh config/zookeeper.properties start kafka: bin/kafka-server-start.sh config/server.properties create a topic: $ bin/kafka-topics.sh --create --topic quickstart-events --bootstrap-server localhost:9092 start consumer: bin/kafka-console-consumer.sh --topic quickstart-events --bootstrap-server localhost:9092 start producer: bin/kafka-console-producer.sh --topic quickstart-events --bootstrap-server localhost:9092 00:00 Intro 01:30 Redis & Kafka Basics 05:45 problem statement 07:08 Traditional solution 10:00 Demo and explanation 25:55 Conclusion Follow me on Linkedin: https://www.linkedin.com/in/anubhavsri/ You can also DM me if you need guidance as a software engineer.