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API Design and Data Model for Chat Application

API Design and Data Model for Chat Application

Learn API design and data model along with design considerations for the chat application.

We'll cover the following...

A chat application is more than just sending and receiving messages. The design of a chat application has to ensure real-time, low-latency, and scalable interactions across devices. API design and data modeling are fundamental to a well-structured chat application. A well-structured API must support instant communication, user presence updates, media sharing, and efficient data retrieval while maintaining privacy, security, and scalability.

This lesson will discuss essential APIs and their data models and explore design considerations that impact the performance of the chat application.

We will explore the following key areas:

Section

What We Covered

API architectural styles

  • Choosing a suitable API architectural style for the chat system.

HTTP protocols

  • Selecting a suitable HTTP protocol for the chat system.

Data formats

  • Deciding on the most suitable data format, i.e., JSON, XML, binary, etc.

Data fetching patterns

  • Choosing an efficient data fetching pattern for real-time communication.

API endpoints

  • Understanding API URLs through which the frontend communicates with the backend.

API endpoints: discuss data model, API design, and request and response format for a few endpoints

  • WebSockets connection

  • Retrieve or upload assets

  • Retrieve chat list

  • Retrieve the message list within a chat

Let’s start with architectural styles!

Architectural style

While traditional APIs use RESTful HTTP endpoints for most interactions, chat applications demand real-time responsiveness. WebSockets enable two-way communication, allowing instant delivery of messages, typing indicators, and presence updates. As a result, some operations shift from HTTP requests to WebSocket events to reduce latency and boost performance.

However, WebSockets do not replace REST APIs entirely. While real-time events (sending messages, updating status, and reading receipts) are handled via WebSockets, stateful data retrieval (such as fetching chat history, media downloads, and user authentication) still relies on RESTful APIs.

Therefore, we’ll use a hybrid approach:

  • Using REST for stateful data retrieval.

  • Using WebSockets for real-time events.

This will ensure that our chat system remains highly responsive and efficient.

Points to Ponder!

1.

Why not use REST for real-time messaging?

Show Answer
Q1 / Q2

HTTP Protocols

We choose HTTP/2 as the primary protocol for communication happening through REST APIs because it enables multiplexing (good for downloading media), reduces latency, and improves overall connection reliability. While HTTP/3 performs better in unreliable network conditions, its adoption is still growing and may not be fully supported across all devices.

Data formats

We use the binary format for uploading and retrieving media files, while we use the JSON format for operations like updating or retrieving user data. The binary format is ...