What is a Client?
Published: 2024-02-22 22:46:48

## Definition

A client is a program or device that requests services or resources from a server in a client-server architecture. It initiates communication, sends requests, and interacts with the server to obtain the desired information or perform specific actions.

## Client-Server Architecture

In the client-server architecture, the client typically initiates communication by sending a request to the server. This request can be for various services or resources, such as data retrieval, file uploads, or authentication. The server, on the other hand, responds to these requests by providing the requested services or resources.

The communication between the client and the server typically occurs over a network, using protocols such as HTTP or TCP/IP. The client sends requests to the server, specifying the desired actions or data, and the server responds with the requested information or performs the requested operations.

This allows for a distributed and scalable approach to software development. It enables the separation of concerns, where the client is responsible for the user interface and user interactions, while the server handles the business logic and data management. This separation allows for easier maintenance, scalability, and flexibility in building complex software systems.

In TypeScript, you can create clients using various approaches and frameworks, depending on your specific requirements and project preferences. One popular approach is to use the Fetch API, which is built into modern web browsers. The Fetch API provides a powerful and flexible way to make HTTP requests from the client to the server.

## What are WebSockets?

When you're using Convex, client-server architecture is facilitated through WebSockets, which act as intermediaries between the client and server. They provide bidirectional communication, operating over a single TCP connection, which is ideal for low-latency, high-performance exchange. Unlike the typical request-response model, WebSockets enable real-time, full-duplex communication between the client and the server.

WebSockets act as a communication channel that allows the server to push data to the client without the need for the client to continuously send requests. This persistent connection eliminates the overhead of establishing new connections for each request, resulting in reduced latency and improved efficiency.

Convex takes advantage of WebSockets to make your application realtime, as the established WebSocket between your database/cache and application will update your app with new data without needing to refresh the page. This enables live chat functionality, collaborative editing, and general multiplayer capabilities. Whenever new information is available, the app server will update your user's client.

## Examples

Here are some examples of clients commonly used in TypeScript development:

1. Web Browsers: Web browsers, such as Chrome, Firefox, and Safari, are the most common type of client in web development. They send HTTP requests to servers and receive responses to display web pages.
2. Mobile Applications: Mobile apps developed using TypeScript, such as those built with frameworks like React Native or Ionic, act as clients. They communicate with servers to fetch data, send user inputs, and receive updates.
3. Desktop Applications: These applications are installed and run on a user's computer and communicate with servers through APIs, allowing users to fetch data, submit forms, and perform various tasks directly from their desktop.
4. Command Line Interfaces (CLIs): TypeScript can be used to build command-line tools or CLIs that act as clients. These clients interact with servers through APIs, enabling developers to perform various tasks from the command line.
5. Server-side Applications: In some cases, TypeScript applications can act as both clients and servers. For example, a TypeScript server application may make requests to external APIs or services, acting as a client to retrieve data or perform certain actions.