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Locations on the Web
- URL
- Stands for Uniform Resource Locator. A URL is used to locate resources on
the network. This is the format used:
scheme://host:port/path
Where each of the components have the following meanings:
- scheme
- This is the method by which information is transfered. Here are some
methods which are used:
- ftp - File Transfer Protocol. Used to perform anonymous ftp transfers
using Web Browsers.
- gopher - The Gopher Protocol. Another form of information retrieval.
- http - HyperText Transfer Protocol. This is the method used by Web
Browsers and servers.
- mailto - Electronic mail.
- news - USENET news. The browser will need to know which news server to
use.
- nntp - USENET news using Network News Transfer Protocol. Allows the
specification of a news server use.
- wais - Wide Area Information Servers. Typically used to query large
databases.
- host
- This is the Internet address of a host. The symbolic name or a four-digit
IP address can be specified.
- port
- This is an optional parameter which can be omitted. Default ports will be
used for each corresponding scheme. If the port is omitted, the colon which
should precede the port should also be omitted.
- path
- The definition of the location depends on the scheme chosen, but for the
World-Wide Web, this location is a file path relative from the server's top
level.
- Examples:
http://www.eng.hawaii.edu/ - College of Engineering Home Page
http://www.w3.org/ - The W3 Consortium Home Page
ftp://ftp.hawaii.edu/ - UH File Archives
gopher://gopher.hawaii.edu/ - UH Gopher Server
- URI
- Uniform Resource Identifier. This is a specification on how identifiers on
the Web are written. One important aspect this specification is how to
deal with the so-called "non-standard" characters which may appear in
URLs. These characters' ASCII (or encoded) values are expressed by a
percent sign, followed by its hexadecimal (base-16) value. For example, a
space can be represented in a URI as follows: %20. For URLs with the tilde
symbol (~), %7E can be used. This representation is used to prevent
possible security problems with scripts which may interpret the data used
for URLs.
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