CSC106 Intermed PC Appls and Programming

URLs

URL is an acronym for Uniform Resource Locator. Every resource on the web (every HTML document, image, sound, etc.) has a unique address given by its URL.

Every URL has several parts:

the protocol required to access the resource
the domain name of the host which has the resource
the name of the file that contains the resource and the path to that file on the host computer (this part of the URL is not required for some URLs)

Some of the more commonly used protocols include:

http: The hypertext transfer protocol is used for transferring web pages between the server and the browser.
ftp: The file transfer protocol is used for copying files between computers on the Internet.
mailto: The mailto scheme is used to open a mail window to allow the user to easily send an email to a specific email address.
file: The file scheme is used to access a file on a local disk.

Examples

http://www.nytimes.com/aponline/world/AP-Iran-Nuclear.html: This is the URL for a web page, therefore, the protocol is http. The next part of the URL is the domain name of the host that contains the web page (www.nytimes.com). The last part of the URL is the path to the file (/aponline/world), and the name of the file that contains the web page (AP-Iran-Nuclear.html).
http://www.middlesexcc.edu: This is the URL for a web page, therefore, the protocol is http. The next part of the URL is the domain name of the host that contains the web page (www.middlesexcc.edu) In this case, a default file will be sent back by the server; usually this default file is named index.html or index.htm.
ftp://www.math.rutgers.edu/pub/ostheime/thesis.ps.gz: This is a URL for a file that can be downloaded from the machine www.math.rutgers.edu. The name of the file is thesis.ps.gz, and the path to the file is /pub/ostheime.
mailto:benweber@benweber.com: This URL brings up an email window with the To: field containing benweber@benweber.com
file:///c|/My%20Documents/mcc/web/index.html: This URL refers to a file on the local C: drive. Notice that there are three slashes in this URL after the protocol name. Also, notice that the drive is indicated by C| rather than C:. Also, there cannot be a blank within a URL, so if there is a space in the file name, it must be indicated by its ASCII code preceded by a %. Since 20 (hex) is the ASCII code for space, the space in the URL is indicated by %20.
myspace.com: There is no protocol in this URL. In a web browser, the protocol defaults to http, so this URL will access the default web page at the host myspace.com.