Uniform resource identifier (URI) and URL

Web Science

Students will be expected to not only define, but also discuss the characteristics of URL and URI. Students will also be expected to describe the purpose of a URL.

Characteristics of a URL

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.

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.

Give the precise meaning of a word, phrase, concept or physical quantity.

Offer a considered and balanced review that includes a range of arguments, factors or hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate evidence.

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

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.