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Real-time Applications: WebSockets vs Server-Sent Events vs WebRTC

Mehdi Rezaei
Mehdi
Author

Introduction to Real-Time Applications

Ever wondered how your favorite apps like WhatsApp, Google Docs, or Zoom work so smoothly in real-time? Welcome to the world of real-time applications, where speed, interaction, and immediacy are the stars of the show. But here’s the twist: not all real-time communication is created equal. Three big names you’ll often come across are WebSockets, Server-Sent Events (SSE), and WebRTC.


In this article, we’ll break them down, compare their strengths and weaknesses, and help you figure out which one is the right fit for your project.


Why Real-Time Communication Matters

Think about it—would you stay on a video call that lags every 5 seconds? Or a chat app that delivers messages 10 minutes late? Exactly! In today’s digital age, users demand instant feedback. Whether it’s live sports scores, trading platforms, or multiplayer games, low-latency communication is crucial.


Understanding the Core Technologies

Let’s unpack what each technology is and what it brings to the table.


What are WebSockets?

WebSockets are a communication protocol that enables full-duplex (two-way) communication between a client and a server over a single, long-lived connection. That means data can flow back and forth without repeatedly opening and closing connections.


What are Server-Sent Events (SSE)?

SSE is a unidirectional communication method where the server can push updates to the client. Think of it like a news ticker: once the connection is open, the server keeps feeding new data without the client asking for it.


What is WebRTC?

WebRTC (Web Real-Time Communication) is a powerful tech that allows peer-to-peer audio, video, and data sharing directly between browsers—no middleman (aka server) required once the connection is set.


How Each Technology Works


How WebSockets Work

WebSockets start with an HTTP handshake, and once the connection is upgraded, it stays open. Both server and client can send messages anytime, which makes it perfect for chat apps or real-time dashboards.


How SSE Works

SSE also begins as an HTTP request, but instead of upgrading, it remains open for the server to stream data to the client. The client can’t send data back over the same connection—only receive.


How WebRTC Works

WebRTC relies on several components like STUN and TURN servers to establish connections. Once the peer-to-peer link is live, it’s incredibly efficient for media streaming.


Key Features and Capabilities


Bi-Directional Communication

WebSockets: ✅ Yes

SSE: ❌ No (server → client only)

WebRTC: ✅ Yes (peer ↔ peer)


Latency and Speed

WebSockets: Very low latency

SSE: Low latency, but not as fast as WebSockets

WebRTC: Ultra-low latency (ideal for live audio/video)


Scalability and Server Load

WebSockets: Requires more server resources for many users

SSE: Lightweight, better for one-way updates

WebRTC: Hard to scale due to peer-to-peer nature


Use Cases of Each Technology


WebSockets Use Cases


Real-time chat apps (like Slack or WhatsApp)

Live sports updates

Online gaming


SSE Use Cases


Stock ticker feeds

Weather updates

Live blog updates



WebRTC Use Cases


Video conferencing (like Zoom, Google Meet)

Screen sharing

Secure peer-to-peer file sharing


Pros and Cons Comparison


Pros and Cons of WebSockets


Pros:

Full-duplex communication

Low latency

Widely supported


Cons:

Needs more server management

Not ideal for simple, one-way updates


Pros and Cons of SSE


Pros:

Easy to implement

Lightweight on server

Great for push notifications


Cons:

One-way only

Limited browser support (IE doesn’t play nice)


Pros and Cons of WebRTC


Pros:

Direct browser-to-browser communication

No need for media servers

Secure (uses encryption by default)


Cons:

Complex setup (STUN/TURN servers)

Harder to scale for many connections


Which One Should You Choose?

Let’s make your decision a little easier.


Best for Chat Applications

Go with WebSockets. The real-time, two-way communication is a perfect fit.


Best for Video/Voice Calls

WebRTC is hands-down the best here. It’s built for media and peer-to-peer connections.


Best for Live Data Feeds

If your app just needs to push updates (like stock prices), SSE is simple and effective.


Conclusion

Real-time technologies are changing how we interact with the web, from instant messaging to live video. Whether you pick WebSockets, SSE, or WebRTC depends on your project needs—speed, direction of communication, and scalability are key deciding factors.


The good news? You don’t have to stick with just one. Hybrid approaches are common too. So, get building and make your app feel alive!

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