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HTTP Protocols and REST APIs

July 24, 2025 4 min read Python Api Web Data-Science Docs IBM-FSSD Rest-Api Http Url

This document explains the HTTP protocol, URL structure, request and response cycles, status codes, and HTTP methods, focusing on REST APIs and their role in web communication and data transfer.

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This document covers the fundamentals of REST APIs, the HTTP protocol, URL structure, request and response cycles, status codes, and HTTP methods. Readers will learn how web communication works and how REST APIs facilitate data transfer between clients and servers.

Introduction to HTTP and REST APIs

The HTTP protocol is a standard for transferring information over the web, including REST APIs. REST APIs operate by sending requests and receiving responses using HTTP messages, often containing JSON data.

URL Structure and Resource Location

A Uniform Resource Locator (URL) identifies resources on the web. It consists of three parts:

PartDescription
SchemeProtocol (e.g., http://)
Base URLInternet address (e.g., <www.ibm.com>)
RouteLocation on the server (e.g., /images/logo.png)

Request and Response Cycle

Clients send HTTP requests to servers, which locate and return resources. The request includes a method (e.g., GET), headers, and optionally a body. The response contains a status code, headers, and the requested resource.

1GET /index.html HTTP/1.0
2Host: www.example.com
3
4Response:
5HTTP/1.0 200 OK
6Content-Type: text/html
7Content-Length: ...
8<html>...</html>

HTTP Status Codes

Status codes indicate the result of a request:

CodeClassMeaning
100InformationalEverything is OK so far
200SuccessRequest succeeded
401Client ErrorUnauthorized request
501Server ErrorNot implemented

HTTP Methods

HTTP methods specify the action to perform:

MethodDescription
GETRetrieve data from server
POSTSend data to server
PUTUpdate data on server
DELETERemove data from server

Conclusion

REST APIs and the HTTP protocol provide a standardized way for clients and servers to communicate and transfer data. Understanding URL structure, request/response cycles, status codes, and HTTP methods is essential for working with web APIs and building data-driven applications.

FAQ

  1. It manages hardware resources
  2. It transfers information over the web
  3. It creates graphical user interfaces
  4. It stores data in databases
(2) The HTTP protocol is used to transfer information over the web, including REST API communication.

The server locates the requested resource and returns it in an HTTP response, including status code, headers, and the resource itself.

  1. A URL consists of scheme, base URL, and route
  2. A URL only contains the base URL
  3. A URL is the same as an IP address
  4. A URL always ends with .html
(1) A URL consists of scheme, base URL, and route to identify resources on the web.

  1. 200 indicates a successful request
  2. 401 means unauthorized
  3. 501 stands for server error
  4. 100 means the request failed
(4) 100 is informational and does not mean the request failed.

MethodDescription
A. GET1. Remove data from server
B. POST2. Retrieve data from server
C. PUT3. Send data to server
D. DELETE4. Update data on server
A-2, B-3, C-4, D-1.

The response header in an HTTP response contains information about the resource, such as content type and length.

True. The response header provides details about the resource returned by the server.

REST APIs use HTTP protocol to standardize communication and data transfer between clients and servers over the web.

The request’s authorization credentials should be checked first to ensure the client is permitted to access the resource.

  1. GET /index.html HTTP/1.0
  2. POST /index.html HTTP/1.0
  3. PUT /index.html HTTP/1.0
  4. DELETE /index.html HTTP/1.0
(1) The correct syntax for a GET request is GET /index.html HTTP/1.0.

Status codes provide clear feedback about the outcome of requests, helping clients handle errors and successes appropriately in web communication.
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