Key concept of System design going backward
I left out some important informations and I want to make things right
Going back to my article about system design, I realized that I took some concepts for granted.
To make good decisions when designing a system, a solid understanding of the key technologies required to build such a platform is essential.
3 Core Technologies Behind Real-Time Communication Apps
Building a real-time communication platform requires more than just a sleek UI and scalable infrastructure. At its core, such an application relies on key technologies that enable instant messaging, seamless API interactions, and high-quality voice and video calls. While many developers are familiar with REST APIs and basic WebSockets, fewer have worked with the powerful protocols that make these platforms truly fast and scalable.
In this article, I want to highlight three essential but often overlooked technologies: WebSockets, gRPC, and WebRTC. These are the foundation of a Discord clone, yet many engineers,especially those new to system design,may not have had the chance to work with them in depth. By understanding their roles, strengths, and trade-offs, you can better design and optimize real-time applications.
Let’s dive into each of these technologies and explore why they are essential for a modern Discord clone.
1. WebSockets – Enabling Real-Time Messaging
At the heart of any instant messaging system lies WebSockets, a protocol designed for persistent, two-way communication between clients and servers. Unlike traditional HTTP, which follows a request-response model, WebSockets establish a continuous connection, allowing messages to flow in real time without the overhead of repeatedly opening new connections.
Why WebSockets Matter
WebSockets are particularly important for chat applications, where real-time message delivery is essential. With WebSockets:
A client receives messages instantly rather than polling the server for updates.
Users see presence indicators (e.g., "typing…" or "online now") with minimal delay.
Event-driven interactions, such as notifications or real-time status updates, become seamless.
How They Work
A WebSocket connection begins as an HTTP request, but instead of closing after a response, it upgrades to a persistent, bidirectional connection. This allows both the client and server to send and receive messages at any time.
While WebSockets are powerful, they require careful handling of reconnections, message ordering, and scaling across multiple servers. That’s where additional technologies come in.
2. gRPC – Efficient API Communication for a Discord Clone
While WebSockets handle real-time interactions, a Discord clone still needs a reliable way to serve structured API requests, fetching message history, managing user data, handling authentication, and more. Many applications default to RESTful APIs with JSON payloads, but a more efficient alternative exists: gRPC (gRPC Remote Procedure Call).
What Makes gRPC Different?
gRPC is a modern RPC framework built on HTTP/2, offering several advantages over REST APIs:
Binary data over Protobuf – Unlike JSON, which is text-based and verbose, gRPC uses Protocol Buffers (Protobuf), a compact and efficient binary format.
Multiplexing – HTTP/2 allows multiple requests to be sent and received simultaneously over a single connection, reducing latency.
Built-in streaming – gRPC natively supports bidirectional streaming, making it a powerful choice for live updates.
Strong typing and auto-generated code – Protobuf enforces strict data contracts and generates client and server code automatically, reducing errors and improving maintainability.
Why gRPC Over REST?
For a Discord clone, gRPC offers clear benefits in terms of speed and efficiency, especially when handling high-throughput API calls. For example:
Fetching thousands of messages in a channel is significantly faster with gRPC’s binary format and multiplexed requests.
Streaming capabilities allow efficient delivery of real-time updates without requiring a dedicated WebSocket for every API call.
Strong typing reduces the risk of API contract mismatches between services.
However, gRPC isn’t always the right choice for public APIs or third-party integrations, where REST and JSON remain more universally supported. But for internal service-to-service communication, it’s a game-changer.
3. WebRTC – Powering Real-Time Voice and Video Calls
A real-time communication platform wouldn’t be complete without voice and video capabilities. This is where WebRTC (Web Real-Time Communication) comes in. Unlike WebSockets and gRPC, which focus on messaging and data exchange, WebRTC is specifically designed for low-latency, peer-to-peer audio and video communication.
Why WebRTC Is Essential
WebRTC enables direct media streaming between users, reducing the need for centralized servers to process and relay audio/video data. This results in:
Lower latency – Avoiding unnecessary hops through a backend server keeps voice and video lag to a minimum.
Reduced server costs – Unlike traditional VoIP systems, WebRTC establishes peer-to-peer connections whenever possible.
Built-in NAT traversal – WebRTC includes mechanisms to work around firewalls and NAT restrictions, making it easier to establish connections even in restrictive network environments.
How WebRTC Works
WebRTC sessions typically involve three key components:
Signaling – Before a direct connection is established, WebRTC relies on a signaling process (often using WebSockets or gRPC) to exchange connection details.
STUN/TURN Servers – These help devices discover their public IP addresses and relay data when direct peer-to-peer connections are not possible.
Peer-to-Peer Streaming – Once a connection is established, audio and video streams flow directly between users with minimal delay.
WebRTC is what makes Discord’s voice channels feel so responsive, even when hundreds of users are connected. It’s also the technology behind many modern video conferencing platforms.
Bringing It All Together
Building a Discord clone isn’t just about writing code,it’s about choosing the right technologies to deliver an experience that feels instantaneous and seamless. WebSockets, gRPC, and WebRTC each play a critical role:
WebSockets enable persistent, bidirectional communication for messaging and live updates.
gRPC provides a fast, efficient way to handle structured API requests and backend communication.
WebRTC powers low-latency voice and video calls through peer-to-peer streaming.
Each of these technologies is powerful on its own, but together they form the backbone of real-time applications like a Discord clone. Whether you’re a junior engineer exploring real-time communication for the first time or a senior architect refining your system design, understanding these technologies will give you the tools to build highly responsive and scalable applications.
In the next sections, we’ll dive deeper into each of these technologies, exploring their implementation details, best practices, and potential challenges.
