http structure - Notes By ShariqSP

Understanding HTTP Request and Response Properties in Postman

HTTP (Hypertext Transfer Protocol) is the foundation of communication on the web, and it consists of requests and responses that pass between clients and servers. When using Postman, a tool for testing and automating API requests, it’s essential to understand the structure and properties of HTTP requests and responses to make effective API calls.

1. HTTP Request Properties

An HTTP request is a message from a client (like Postman) to a server to perform an action, such as retrieving or updating data. The key properties of an HTTP request include:

• HTTP Method: Defines the type of operation to be performed. Common methods include:
  • GET: Requests data from a server. Example: Retrieving user details.
  • POST: Submits data to be processed. Example: Adding a new user.
  • PUT: Updates existing data. Example: Modifying a user’s information.
  • DELETE: Deletes specified data. Example: Removing a user.
• URL (Uniform Resource Locator): The endpoint where the request is sent. It consists of the server's address and, optionally, a path to the resource (e.g., `https://api.example.com/users`). In Postman, the URL can be entered directly into the request bar.
• Headers: Metadata providing information about the request. Common headers include:
  • Content-Type: Specifies the data type being sent, such as `application/json` or `application/xml`.
  • Authorization: Used for authentication, often containing a token.
  • Accept: Indicates the response format expected (e.g., `application/json`).
• Body: Data sent with the request, especially for methods like POST and PUT. In Postman, you can choose the format of the body (JSON, XML, form-data, etc.). For instance:

              {
                  "name": "John Doe",
                  "email": "johndoe@example.com"
              }
                          

• Query Parameters: Key-value pairs appended to the URL, typically used for filtering or sorting results. Example: `https://api.example.com/users?age=25&status=active`.

2. HTTP Response Properties

The server sends back an HTTP response after processing the client’s request. Key properties of an HTTP response include:

• Status Code: A three-digit code that indicates the result of the request. Common status codes are:
  • 200 OK: The request was successful.
  • 201 Created: The request was successful, and a new resource was created (common for POST requests).
  • 400 Bad Request: The server couldn’t understand the request due to invalid syntax.
  • 401 Unauthorized: Authentication is needed, or it failed.
  • 404 Not Found: The requested resource could not be found.
  • 500 Internal Server Error: The server encountered an error.
• Headers: Provide metadata about the response. Examples include:
  • Content-Type: The format of the returned data (e.g., `application/json`).
  • Server: Information about the server handling the request.
  • Cache-Control: Directs caching mechanisms to store or not store the response.
• Body: The main content of the response. For example, a GET request to retrieve user data might return:

              {
                  "id": 1,
                  "name": "John Doe",
                  "email": "johndoe@example.com"
              }
                          

  In Postman, the response body is displayed in different formats like JSON, HTML, or plain text.
• Cookies: Some responses may contain cookies, which are stored on the client side and may be used for session management or tracking.

3. Example Usage in Postman

Let’s go through an example of sending a POST request using Postman to create a new user:

• HTTP Method: POST
• URL: `https://api.example.com/users`
• Headers:
  • Content-Type: `application/json`
  • Authorization: `Bearer {token}`
• Body (JSON format):

              {
                  "name": "Jane Doe",
                  "email": "janedoe@example.com",
                  "password": "securepassword"
              }
                          

When you send the request in Postman, the server may respond with:

• Status Code: 201 Created
• Headers:
  • Content-Type: `application/json`
  • Location: `https://api.example.com/users/2` (indicates where the new resource can be accessed)
• Body:

              {
                  "id": 2,
                  "name": "Jane Doe",
                  "email": "janedoe@example.com"
              }
                          

Understanding these request and response properties will allow you to effectively use Postman for API testing and debugging, ensuring that your requests are properly structured and responses are interpreted accurately.

Complete List of HTTP Status Codes and Their Meanings

4xx Client Error Status Codes

5xx Server Error Status Codes