Design Concepts

How does Uber coordinate millions of drivers and riders in real-time? What enables Netflix to stream content to hundreds of millions of users simultaneously? To answer lies in fundamental system arc Today's applications are complex systems with many moving parts that need to work together seamlessly. Understanding the core arc Microservices is an arc T A shopping application might have separate services for user accounts, product catalog, shopping cart, payment processing, and order fulfillment. Each service handles one specific business capability. The key advantages are flexibility and scalability. Teams can work independently on different services without coordination overhead. Each service can use the technology stack best suited for its specific needs. Services can be deployed and scaled independently based on their individual requirements. However, microservices introduce complexity. It used to be simple function calls between modules become network requests that can fail, time out, or return unexpected results. You need sop The general principle is that microservices make sense when you have sufficient complexity to justify the coordination overhead. For simple applications of small teams, the benefits often don't outweigh the additional operational burden. Using an authorization of security mechanisms that verify user identity and control access to system resources. Every system needs reliable ways to answer two fundamental questions. Who is these security concerns become more complex as systems grow and distribute across multiple components. Modern systems typically use token-based authentication. When users log in, they receive a token that proves their identity. T Authorization determines what authenticated users can access. Role-based systems assign permissions to roles More sophisticated systems use attribute-based policies that consider factors The challenge in distributed systems is maintaining consistent security across all components. Solutions include passing security tokens between systems and implementing centralized policy engines that provide consistent authorization decisions throughout the system. Service discovery enables system components to locate and communicate with each other in dynamic environments where addresses and availability change frequently. In traditional applications, with my hardcore database connection strings or API endpoints, for the modern cloud deployments, services can be created, destroyed, and relocated automatically based on demand. Their network addresses change constantly as systems scale up and down. Service discovery maintains a registry-available services in their current locations. When a service starts, it registers itself with the discovery system. When other components need to communicate with it, they query the registry to find the current address. T Popular implementations include DNS-based discovery, dedicated registry services, and integrated solutions provided by container orchestration platforms. The key challenge is handling failures gracefully. What happens when the registry itself is unavailable? How do we detect when a service has crashed but hasn't been properly removed from the registry? These are important considerations when choosing a service discovery solution. An API gateway provides a single entry point for client requests, handling routing, security, and cross-cutting concerns before forwarding requests to backend services. Without a gateway, client applications will need to know about every backend service and how to communicate with w T Clients would also need to handle concerns The API gateway centralizes these concerns. It presents a unified interface to clients w It can aggregate responses from multiple services, transform data formats, and manage authentication and authorization. For example, when we open a mobile app, the gateway might authenticate our request, fetch our profile from one service, get our recent activity from another, and combine everyt It's one API call. Modern gateway also provides operational features The tradeoff is that the gateway becomes a critical component in your system arc We need to choose a solution that can handle Message queues enable asynchronous communication between system components by allowing them to exchange messages without requiring both parties to be available simultaneously. When one part of the system needs to notify others about an event, Other components can subscribe to these messages and process them at their own pace. T Message queues provide different delivery guarantees depending on the requirements. At most ones, delivery ensures messages are never duplicated but might occasionally be lost. At least one delivery guarantee messages won't be lost but might be delivered multiple times. Exactly once delivery is the most complex but ensures each message is processed exactly once. The tradeoff is increased complexity in handling failures and maintaining data consistency. When operations span multiple components connected by queues, we need to carefully consider how to handle partial failures and ensure data integrity. WebSocket enables real-time bi-directional communication between clients and servers over a persistent connection, allowing either party to initiate data exchange at any time. Traditional XJDP follows a request-response pattern where only clients can initiate communication. The server cannot send data to the client unless the client first makes a request. For applications that need real-time updates, WebSocket solves t Once established, both client and server can send messages independently without waiting for requests. The server can push updates to clients immediately when events occur, eliminating the need for constant polling. T It also reduces server load by eliminating constant polling requests. A single server can efficiently maintain many concurrent WebSocket connections using event-driven programming models. However, WebSocket introduces operational complexity. Un Network interruptions, proxy servers, and corporate firewalls can interfere with persistent connections. Applications need robust reconnection logic, heartbeat mechanisms to detect broken connections, and fallback strategies for environments that don't support WebSocket. These patterns form the foundation of modern system design arc The key is choosing the right combination of patterns for our specific requirements. Not every system needs all of these components, but knowing when and how to apply each one will help us build systems that are scalable, maintainable, and reliable. One more content From system design to coding challenges, behavioral tips to ML concepts, it's all there. One subscription, complete access. Get 50% off at bytebitego. com