Client-server architecture in Rest API - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the basic idea of client-server architecture?

It is a way to organize computers where one (the client) asks for services or data, and another (the server) provides them.

beginner

What role does the server play in client-server architecture?

The server waits for requests from clients and sends back the requested data or performs actions.

beginner

What is a client in client-server architecture?

A client is a program or device that sends requests to the server to get data or services.

intermediate

Why is client-server architecture useful for web applications?

It separates the user interface (client) from data storage and processing (server), making apps easier to manage and scale.

beginner

Give a simple real-life example of client-server architecture.

When you use a web browser (client) to visit a website, the browser asks the website's server for pages and shows them to you.

In client-server architecture, who initiates communication?

A The server

B The client

C Both at the same time

D Neither

The client always starts by sending a request to the server.

Which of the following is NOT a characteristic of a server?

A Waiting for requests

B Sending responses

C Requesting data from clients

D Providing services

Servers do not request data from clients; clients request data from servers.

What is the main benefit of separating client and server in an application?

A Improves security by hiding server details

B Makes the app slower

C Clients and servers must be the same device

D Removes the need for internet

Separating client and server helps protect server data and allows better control over access.

Which device usually acts as a client in web browsing?

A Database server

B Firewall

C Router

D Web browser

The web browser is the client that requests web pages from servers.

In client-server architecture, what happens after the server receives a request?

A It processes the request and sends a response

B It ignores the request

C It sends the request to another client

D It shuts down

The server processes the request and replies with the needed data or confirmation.

Explain how client-server architecture works using a simple everyday example.

Think about how your phone or computer talks to websites.

List the main roles of clients and servers in client-server architecture.

Who asks and who answers?

Practice

1. In a client-server architecture, what is the main role of the client?

easy

A. To request data or services from the server

B. To store and manage data permanently

C. To control the network hardware

D. To provide power to the server

Solution

1. Step 1: Understand client role

   The client is the part of the system that asks for information or services.

2. Step 2: Differentiate from server role

   The server responds to client requests by sending data or services.

3. Final Answer:

   To request data or services from the server -> Option A

4. Quick Check:

   Client requests, server responds [OK]

Hint: Clients always ask; servers always answer [OK]

Common Mistakes:

• Confusing client with server
• Thinking client stores data permanently
• Assuming client controls network hardware

2. Which of the following is the correct way a client sends a request to a server in REST API?

easy

A. Using a SQL SELECT statement

B. Using an HTTP GET method

C. Using a FTP upload command

D. Using a local file read operation

Solution

1. Step 1: Identify REST API request methods

   REST APIs use HTTP methods like GET, POST, PUT, DELETE to communicate.

2. Step 2: Match method to client request

   GET is used by clients to request data from servers.

3. Final Answer:

   Using an HTTP GET method -> Option B

4. Quick Check:

   REST client requests use HTTP methods [OK]

Hint: REST clients use HTTP verbs like GET to ask [OK]

Common Mistakes:

• Confusing SQL with REST API
• Using FTP commands for REST requests
• Thinking local file reads send requests

3. What will the server respond with if a client sends a GET request to /users/123 and the user exists?

medium

A. A JSON object with user details

B. An error message saying 'User not found'

C. A redirect to the homepage

D. A blank page with no content

Solution

1. Step 1: Understand GET request to resource

   A GET request to /users/123 asks for user data with ID 123.

2. Step 2: Server response when user exists

   If user exists, server sends back user details, usually as JSON.

3. Final Answer:

   A JSON object with user details -> Option A

4. Quick Check:

   GET existing resource returns data [OK]

Hint: GET returns data if resource exists, else error [OK]

Common Mistakes:

• Assuming error if user exists
• Thinking GET causes redirect
• Expecting blank page on success

4. A client sends a POST request to create a new user, but the server responds with a 404 error. What is the most likely cause?

medium

A. The client sent too much data

B. The client used the wrong HTTP method

C. The server successfully created the user

D. The server URL endpoint is incorrect or missing

Solution

1. Step 1: Understand 404 error meaning

   404 means the requested URL or endpoint was not found on the server.

2. Step 2: Link error to cause

   If POST returns 404, likely the client sent request to wrong or missing URL.

3. Final Answer:

   The server URL endpoint is incorrect or missing -> Option D

4. Quick Check:

   404 means URL not found [OK]

Hint: 404 means wrong or missing URL endpoint [OK]

Common Mistakes:

• Confusing 404 with method error
• Assuming success on 404
• Thinking data size causes 404

5. You want to design a REST API where clients can update user info only if they provide a valid token. Which client-server architecture concept helps enforce this?

hard

A. Client directly modifying server database

B. Client caching data locally

C. Authentication and authorization on the server

D. Server sending data without checks

Solution

1. Step 1: Identify security need

   Allowing updates only with valid token means controlling access.

2. Step 2: Apply client-server security concept

   Authentication verifies identity; authorization controls permissions on server side.

3. Final Answer:

   Authentication and authorization on the server -> Option C

4. Quick Check:

   Access control = Authentication + Authorization [OK]

Hint: Use server-side auth to control client access [OK]

Common Mistakes:

• Thinking client caches control access
• Assuming server sends data without checks
• Believing client can modify database directly