Publish-Subscribe Architecture

1. Introduction

The Publish-Subscribe (Pub-Sub) architecture is a messaging pattern where senders (publishers) send messages without knowing the receivers (subscribers). This pattern is widely used in distributed systems, enabling decoupling of components.

2. Key Concepts

• **Publisher**: The component that sends messages.
• **Subscriber**: The component that receives messages.
• **Message Broker**: An intermediary that facilitates communication between publishers and subscribers.
• **Topics**: Channels through which messages are sent and received.

3. Architecture Overview

The architecture typically includes the following components:

Flowchart

    graph TD;
        A[Publisher] -->|Publish Message| B[Message Broker];
        B -->|Distribute Message| C[Subscriber];
    

4. Implementation

Here's an example of implementing a simple Pub-Sub system using Python with a basic in-memory message broker:

class MessageBroker:
    def __init__(self):
        self.subscribers = {}

    def subscribe(self, topic, subscriber):
        if topic not in self.subscribers:
            self.subscribers[topic] = []
        self.subscribers[topic].append(subscriber)

    def publish(self, topic, message):
        if topic in self.subscribers:
            for subscriber in self.subscribers[topic]:
                subscriber.receive(message)

class Subscriber:
    def __init__(self, name):
        self.name = name

    def receive(self, message):
        print(f"{self.name} received: {message}")

broker = MessageBroker()

sub1 = Subscriber("Subscriber 1")
sub2 = Subscriber("Subscriber 2")

broker.subscribe("news", sub1)
broker.subscribe("news", sub2)

broker.publish("news", "New article published!")
        

5. Best Practices

• Use topics wisely to avoid message overload.
• Implement message acknowledgment to ensure delivery.
• Consider message persistence for reliability.
• Monitor performance and scale the message broker as necessary.

6. FAQ