Client-Server Communication in APIs

Back to API Design
Arjit Sharma
01 Min

A way for devices to interact with each other over network is called client-server communication.

Now that we understand how the Internet works, let’s zoom in on how computers talk to each other in the world of APIs. Whether it’s your app hitting a backend service or two microservices exchanging data - it’s all client-server communication powered by API protocols.

What’s Client-Server Communication?

At its core, it’s simple:

  • The client is whoever initiates the conversation (like a web browser, mobile app, or a script making an API call).
  • The server is who responds with the data or functionality (your backend service, database, or cloud function).

They talk over a network (usually the Internet), using protocols like HTTP, WebSocket, or RPC. This request-response pattern underlies every API interaction, regardless of the protocol.

Communication Patterns

1. Request-Response

Most common pattern where client makes a request, waits for server response. Example: REST APIs, database queries.

2. Push-Based

Server pushes updates to clients, while client maintains an open connection. Example: WebSocket, Server-Sent Events.

3. Publish-Subscribe

Clients subscribe to topics/events and server publishes updates to subscribers. Example: Message queues, event streaming

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