gRPC PubSub System

A simple publish-subscribe messaging system built with gRPC and Go. Send messages to topics and have multiple clients receive them in real-time.

Getting Started

1. Install dependencies

make deps

2. Start the broker server

The broker must run first since it handles all message routing:

make run-broker

This starts the broker on localhost:8080.

3. Start a consumer

Open a new terminal and run:

make run-consumer

The consumer will connect to the broker and subscribe to the "kubernetes" topic.

4. Publish some messages

Open another terminal and run:

make run-publisher

The publisher will send several "New release: Kubernetes 1.30 is out" messages to the "kubernetes" topic. You'll see the consumer receive these messages in real-time.

How it works

The system uses three gRPC methods defined in pubsub.proto:

1. Publish: Sends a message to a topic
2. Subscribe: Opens a stream to receive messages from a topic
3. Unsubscribe: Stops receiving messages from a topic

The broker keeps track of which consumers are subscribed to which topics. When a publisher sends a message, the broker looks up all subscribers for that topic and forwards the message to each one.

Each consumer gets a unique ID (UUID) so the broker can track subscriptions properly.

Protocol Buffer Definition

The gRPC service is defined in pkg/protobuf/pubsub.proto with three main operations:

• Publish(PublishRequest) returns (PublishResponse) - Send a message
• Subscribe(SubscribeRequest) returns (stream PayloadStream) - Receive messages
• Unsubscribe(UnsubscribeRequest) returns (UnsubscribeResponse) - Stop receiving

Messages contain a topic name and payload bytes, so you can send any kind of data.