What is a URI?

URI (Uniform Resource Identifier) is a sequence of characters that identifies an abstract or physical resource. A URI can be classified as a URL (Uniform Resource Locator), which provides means to locate it, or a URN (Uniform Resource Name), which assigns a unique name within a specific namespace.

Structure of URI:

A URI typically consists of the following components:

• Scheme: Defines the protocol or access mechanism to the resource (e.g., http, https, ftp, file).
• Authority: Contains information about the source of authorization, usually in the format [userinfo@]host[:port].
• Path: Specifies the particular resource within the authority.
• Query: Contains additional data for the request, presented as key-value pairs separated by &.
• Fragment: Identifies a secondary resource.

Differences between URI, URL, and URN:

Type	Description	Example
URI	Resource identifier (locator OR name)	urn:isbn:0-486-27557-4
URL	Resource locator	https://www.example.com/page.html
URN	Resource name	urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6

• URL indicates how to access the resource and its location.
• URN provides a persistent, unique name for the resource regardless of its location.
• URI is a generalization of both URL and URN.

In Python, the urllib.parse module is often used for working with URI/URL.

# Example of parsing a URL string
from urllib.parse import urlparse

uri_string = "https://user:pass@www.example.com:8080/path/to/resource?query=value#fragment"
parsed_uri = urlparse(uri_string)

# Accessing components
print(parsed_uri.scheme)     # Output: https
print(parsed_uri.netloc)     # Output: user:pass@www.example.com:8080
print(parsed_uri.path)       # Output: /path/to/resource
print(parsed_uri.query)      # Output: query=value
print(parsed_uri.fragment)   # Output: fragment