Software Development Skills - Message Broker Exercise Boilerplate

Definition

A message broker is a component that routes messages.

The creator of a message is called producer and the reader of a message is called consumer.

Messages are routed using a topic - this is a string value that categorizes a message.

Requirements

When multiple consumers register for a single topic, messages should be consumed by all of them. Some topics may not have any consumers registered to them at all.

The message broker should be designed in such a way so that consuming messages in one consumer will not “starve” other consumers. Also - do not allow starvation between topics.

We need you to code a message broker that implements the following interface:

public interface IMessageBroker {

   void register(String topic, ConsumerCallback consumer);
   
   void send(Message message);
   
}

Design

Please describe the design for a multi-threaded message broker that complies with the above requirements

Implementation

Implement the message broker

Test your code:

1. Register 3 consumers:

   i. Consumer 1 registers for topic A

   ii. Consumer 2 registers to topics B and C

   iii. Consumer 3 registers to topics A, B, and C

2. To simulate message consumption add 1 millisec sleep to each topic callback.

3. Send 50,000 messages per topic.

Feel free to use the boilerplate code in this repo, or start from scratch.