Client-Server Model
Software Engineer path · lesson 62 of 99Animate the end-to-end data flow from client through the web and application tiers down to the database.
(Browser)
(Nginx/Apache)
(Node/Python/Java)
(Postgres/MySQL)
Production Architectures
E-commerce Platform (Amazon-style)
Massive scale with microservices architecture handling millions of concurrent users.
Latency goal: <200ms for page loads, <100ms for API calls
Social Media Platform (Twitter-style)
High-throughput system optimized for real-time updates and timeline generation.
Scale: 500M+ tweets/day, 6,000 tweets/second peak
Banking System
High-security, ACID-compliant system with strict consistency requirements.
Requirements: 99.99% uptime, strong consistency, audit logging
Content Streaming (Netflix-style)
Global CDN architecture optimized for high-bandwidth video delivery.
Optimization: 95% of traffic served from CDN edge locations
Scaling Strategies
| Strategy | Approach | Pros | Cons |
|---|---|---|---|
| Vertical (Scale Up) | Add more power to existing machines | Simple, no code changes | Hardware limits, single point of failure |
| Horizontal (Scale Out) | Add more machines | Unlimited scaling, fault tolerance | Complex, data consistency challenges |
| Caching | Store frequently accessed data | Reduced latency, lower database load | Cache invalidation, memory costs |
| Load Balancing | Distribute requests across servers | Better utilization, fault tolerance | Session management, complexity |
Little's Law for Capacity Planning
Security & Best Practices
Security Best Practices
- • HTTPS everywhere with TLS 1.3+
- • Input validation and sanitization
- • Authentication & authorization (OAuth, JWT)
- • Rate limiting and DDoS protection
- • Regular security audits and updates
Common Vulnerabilities
- • SQL injection attacks
- • Cross-site scripting (XSS)
- • Cross-site request forgery (CSRF)
- • Man-in-the-middle attacks
- • Privilege escalation
Defense in Depth
Follow one request
Order the path of a request from the browser to the database and back.
Tap a piece, then tap where it goes — or drag it. Tap the tray to take one back.
- 1Drop a step here
- 2Drop a step here
- 3Drop a step here
- 4Drop a step here
- 5Drop a step here
Test your knowledge
In a standard 3-tier architecture, which tier is responsible for executing business rules?
The short version
Think of a restaurant: The Client is the customer ordering, the Web Server is the waiter taking the order, the App Server is the chef cooking, and the Database is the pantry where ingredients are stored.
In more depth
The Client-Server Model
The fundamental architecture of the web, separating requestors (clients) from providers (servers).
The 3-Tier Architecture
Separating these tiers allows each to scale independently based on their unique resource demands.
Interview Questions
References & Further Reading
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