Engineering
Communication Patterns
Understanding how data travels between systems is crucial for designing scalable applications.
Mar 202510 min read
Understanding how data travels between systems is crucial for designing scalable applications.
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References & Disclaimer
This content is adapted from Mastering System Design from Basics to Cracking Interviews (Udemy). It has been curated and organized for educational purposes on this portfolio. No copyright infringement is intended.
How Clients and Servers Communicate
Communication follows a basic sequence:
- Client sends a request (HTTP, SQL, etc.).
- Request is transmitted over the network.
- Server receives and processes the request.
- Server sends a response.
- Client receives and processes the response.
The Request-Response Cycle (HTTP Example)
Browser requests https://example.com
DNS resolves domain to IP address
Browser sends HTTP GET request to web server
Web server processes request (queries DB if needed)
Server sends HTTP response (e.g., 200 OK)
Browser renders the webpage
Synchronous vs Asynchronous Communication
| Pattern | Description | Example |
|---|---|---|
| Synchronous | Client waits for a response before proceeding (Blocking). | REST APIs, Traditional web apps. |
| Asynchronous | Client doesn't wait and can perform other tasks (Non-Blocking). | WebSockets, Background jobs, AJAX. |
Synchronous Communication (Blocking)
Asynchronous Communication (Non-Blocking)
Stateless vs Stateful Servers
Stateless Servers
- No memory of past interactions; each request is independent.
- Benefits: Easily scalable, simple caching, better load balancing.
- Example: REST APIs, HTTP servers.
Stateful Servers
- Maintain session information across multiple requests.
- Benefits: Personalized user experiences, seamless state tracking.
- Example: Multiplayer games, Real-time banking.
Importance of DNS in Large-Scale Systems
DNS isn't just for naming; it's a tool for traffic management:
- Ensuring High Availability: Load balancing using DNS.
- DNS Failover: Automatically switching to a passive server if the primary goes down.
- CDN Integration: Directing users to the nearest "edge" node for content delivery.