I guess we can also work with RabbitMQ as a message broker that enables asynchronous communication in distributed systems by using queues to store messages until consumed. Key components include producers that send messages, queues that hold them, consumers that process them, and exchanges that route messages. The main types of exchanges are direct, fanout, topic, and headers. Benefits of RabbitMQ include decoupling of components, scalability, reliability, load balancing, and fault tolerance through clustered queues. Common use cases involve task queues for background processing, event broadcasting, microservices communication, and data streaming for logs and telemetry.

Try to understand what the system really requires, vertical or horizontal scalability. Search for bottlenecks, in places where multiple parallel calls converge to single call. Design the system to do non blocking calls and fail fast. Reduce context switching by building separate components for micro tasks, executing in their own space. Check if strong consistency is really required or eventual consistency can also work. Calculate hardware and network scalability requirements. Integrate code analyzers into the build system. Regularly profile and do performance and load tests. Help team to think and develop software with performance in mind. Study designs of other highly scalable systems to get better ideas.

Scalability can be categorized into two types: vertical scaling (increasing the size and power of each machine) and horizontal scaling (increasing the number of machines). If you take a service-oriented approach, you can add more machines which work together concurrently as a distributed system to provide service. The horizontally scalable distributed system can also increase the size of each machine; however, vertical scaling has a limit which will be reached way before the horizontal limit is reached. Horizontal scaling involves additional complexity due to the need for coordination, so often it's easier to simply scale vertically until you get close to the vertical scaling limit. Modular architecture scales horizontally with less effort.