Introduction
Have you ever wondered how a simple web page loads in your browser or how a search query returns instant results? Behind every interaction you make on the web, there’s a complex yet seamless communication process happening between your browser (the client) and the server. This interaction is governed by the Client-Server Architecture and the HTTP request-response cycle. But what exactly happens behind the scenes when you click that search button or type in a website URL?
In this article, we’ll dive into the fundamentals of Client-Server Architecture, including its different types, and break down the HTTP Request-Response Cycle to give you a clearer understanding of the processes that make the web function.
Client-Server Architecture
what is client?
The client is the application or device requesting a service or resource. When you open a browser and type in a URL, you’re essentially requesting access to a server that holds the web page you want to view.
what is server ?
The server is a powerful machine that waits for requests from clients. When it receives a request, it processes it, retrieves the necessary data, and sends it back to the client. Servers can host web pages, process data, manage databases, and perform various other functions.
Types of Client-Server Architecture
There are various types of client-server architecture, each designed to handle different workloads and provide distinct benefits.
1. One-Tier Architecture (Single-Tier Architecture)
In this model, the client and the server exist on the same machine. The application runs locally, meaning there’s no distinction between the client and the server. All operations—such as data processing, user interface rendering, and database management—happen on the same system.
Example:
A desktop application like Microsoft Word or a simple offline game where everything runs locally on your computer.
2. Two-Tier Architecture (Client-Server Model)
This is the traditional model where the client and server are distinct, but the responsibilities are split between the two. The client (often a web browser) interacts directly with the server to request resources. The server processes the request and returns the data to the client.
Client Side: The user interface or application that makes requests.
Server Side: The server that hosts the resources (such as a website) and processes requests.
Example:
Most traditional web applications follow this model. When you visit a website, your browser (client) sends a request to a web server, which processes the request and serves you the web page.
3. Three-Tier Architecture (Multi-Tier Architecture)
This model introduces an additional layer between the client and server to better distribute the workload. The three tiers are:
Presentation Layer (Client): The user interface or client-side application.
Logic Layer (Application Server): The middle layer that handles business logic and computations. This layer is responsible for processing requests and performing the necessary calculations.
Data Layer (Database Server): The backend layer that manages the data, usually in a database. It handles queries, updates, and storage.
Example:
In an e-commerce website, when you search for a product:
The client (browser) sends a request to the application server.
The application server performs the business logic (e.g., searching the product).
The database server stores the product data and sends back the result.
