Web Communication Protocols

1. HTTP (Hypertext Transfer Protocol)

Theory

HTTP is a request-response protocol where the client (browser) sends a request to the server, and the server responds with the requested data. It is stateless, meaning each request is independent.

Use Cases

✅ Static content delivery (HTML, CSS, JS, images, videos).
✅ RESTful APIs for client-server communication.
✅ CRUD operations (Create, Read, Update, Delete).

Limitations

❌ No real-time updates without polling or websockets.
❌ Each request establishes a new connection, adding latency.

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2. WebSockets

Theory

WebSockets provide a persistent, full-duplex communication channel between the client and server over a single TCP connection. Unlike HTTP, WebSockets enable real-time bidirectional communication.

Use Cases

✅ Chat applications (Slack, WhatsApp, Messenger).
✅ Live notifications and real-time stock market updates.
✅ Multiplayer gaming (instant interactions between players).
✅ Collaborative tools (Google Docs-style live editing).
✅ Video/audio streaming.

Limitations

❌ Not ideal for one-time or infrequent updates.
❌ Requires more server resources due to persistent connections.
❌ WebSocket connections may be blocked by certain firewalls or proxies.

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3. HTTP Polling

Theory

HTTP Polling is a technique where the client periodically sends requests to the server to check for updates. The server responds with the latest data (if any).

Use Cases

✅ When WebSockets are not supported but real-time updates are needed.
✅ Less frequent updates (e.g., refreshing a dashboard every 30 seconds).
✅ Environments where long-lived connections are not feasible.

Limitations

❌ Higher server load due to frequent requests.
❌ Increased latency since updates arrive only on the next request cycle.
❌ Inefficient for high-frequency real-time data.

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4. SSE (Server-Sent Events)

Theory

SSE is a one-way communication method where the server pushes updates to the client over an HTTP connection. The connection remains open, and the server sends data when available.

Use Cases

✅ Live feeds (news updates, sports scores).
✅ Stock market updates where only the client needs to receive data.
✅ Real-time notifications that don’t require two-way communication.
✅ Realtime analytics dashboards.

Limitations

❌ Only supports server-to-client communication (not bidirectional).
❌ Limited browser support (mainly works well in modern browsers).
❌ Less scalable compared to WebSockets for very high concurrency.

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Comparison Table

Feature	HTTP	WebSockets	HTTP Polling	SSE
Real-time	❌ No	✅ Yes	⚠️ Delayed	✅ Yes (one-way)
Bidirectional	❌ No	✅ Yes	❌ No	❌ No
Efficiency	⚠️ Medium	✅ High	❌ Low (high overhead)	✅ High
Use Case	Static content, APIs	Chat, notifications, games	Periodic updates	Live updates
Latency	High	Low	Medium-High	Low
Scalability	High	Medium	Low	Medium

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When to Use What?

• Use HTTP for standard web page requests and API calls.
• Use WebSockets for real-time, bidirectional communication like chat apps and multiplayer games.
• Use HTTP Polling when WebSockets are not an option and occasional updates are needed.
• Use SSE for real-time server-to-client updates where bidirectional communication is unnecessary.