Structure of the Internet: URIs
Resources such as documents, files and folders sitting on the internet need a method to identify them and access them. URIs provide a way to linking to these resources. There are two types of URI, but you only need to know URL for the exam:
- Uniform Resource Name (URN) - the name of a resource, but not its exact location.
e.g. urn:isbn:0486419266
The URN for R.U.R. (1921 play), identified by its book number.
- Uniform Resource Locator (URL) - the exact location of a resource.
e.g. http://www.gutenberg.org/catalog/world/readfile?fk_files=85821
The project gutenberg page for the R.U.R. book
Uniform Resource Locator (URL)
[edit | edit source]A URL is a URI that, "in addition to identifying a resource, provides a means of locating the resource by describing its primary access mechanism (e.g., its network location)".[1] URLs allow us to specify the domain name and exact location of a resource on the internet. For example, the following links to a picture on wikicommons:
http://commons.wikimedia.org/wiki/File:George_Clausen_WWI_poster.jpg
We can break this down into its constituent parts:
We can therefore summarise a URL as follows:
Exercise: Uniform Resource Identifiers Describe the difference between a URN and a URL Answer:
Give the 3 parts that make up a URL Answer:
For the following address: describe the parts:
Answer:
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References
[edit | edit source]- ↑ Tim Berners-Lee, Roy T. Fielding, Larry Masinter. (January 2005). “Uniform Resource Identifier (URI): Generic Syntax”. Internet Society. RFC 3986; STD 66.