Uniform resource identifier (URI) and URL

Web Science

Characteristics of a URI

A Uniform Resource Locator (URL), is a reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier (URI).

• Please click here for the official url specification

• URL's have different parts. Every URL MUST have:
  • scheme and host
• URL's have different parts. Every URL MIGHT have:
  • user information
  • port
  • query
  • fragment

Please click here for an example of these different parts. In your normal day-to-day use, you probably only use a scheme and a host.

Please click here to see a list of all the available schemes. There's a LOT more than HTTP and HTTPS!!

Example of a URL

The following figure displays two example URIs and their component parts.

                    hierarchical part
        ┌───────────────────┴─────────────────────┐
                    authority               path
        ┌───────────────┴───────────────┐┌───┴────┐
  abc://username:password@example.com:123/path/data?key=value&key2=value2#fragid1
  └┬┘   └───────┬───────┘ └────┬────┘ └┬┘           └─────────┬─────────┘ └──┬──┘
scheme  user information     host     port                  query         fragment

  urn:example:mammal:monotreme:echidna
  └┬┘ └──────────────┬───────────────┘
scheme              path

Purpose of a URL

A URL is a string of characters used to identify a resource. The purpose of a URL is to easily retrieve network resources. URL's also make linking to resources easier.

Do you understand this?

• identify each part of this URI:

file:///Users/billdagjana/Desktop/

• Which one of these does a URI NOT do:
  • Enable easier access to resources
  • Provide excellent resources for linking between resources
  • Allow you to more quickly download content
  • Provide a unified syntax to access remote resources

Standards

These standards are used from the IB Computer Science Subject Guide

• Identify the characteristics of a uniform resource identifier (URI) URL.
• Describe the purpose of a URL.

a group or system of interconnected people or things.

Provide an answer from a number of possibilities. Recognize and state briefly a distinguishing fact or feature.

Provide an answer from a number of possibilities. Recognize and state briefly a distinguishing fact or feature.

Give a detailed account or picture of a situation, event, pattern or process.