The World Wide Web  Exploring the World-Wide-Web
URL's
This page describes:
URLs, or Uniform Resource Locators, are a standard
way of specifying the location of Internet computer files. Using its URL, you can retrieve
a file from any computer on the Internet (or tell someone else how to retrieve it).
URLs are very similar to e-mail addresses. However, they
include additional information that makes them considerably more powerful.
Below, the URL for this page is analyzed part by part.
Click on each part pf the URL for its meaning.
http://www.jvlnet.com/support/www/urls.htm
- http://www.jvlnet.com/support/www/urls.htm
- The first part of the URL identifies the protocol necessary
to retrieve the file. The scheme "http://" indicates that the file is a web page
(remember that HTTP stands for "Hypertext Transfer Protocol," the standard for
web servers). You will also see URLs using other schemes, such as:
- gopher://
- Identifies a file on a gopher server.
- news://
- Identifies an item from a Usenet news group.
- ftp://
- Identifies a file that can be downloaded from an FTP server.
Web browsers can process URLs specifying other server
protocols, so that a program like Navigator can also act like a gopher client, a news
reader, and an ftp client.
- http://www.jvlnet.com/support/www/urls.html
- This part of the URL is in the same format as part of an
e-mail address. It is the domain name of the machine on which the file is located.
Understanding domain names can help you guess URLs.
Interpreting this domain name from right to left, we can decipher some information about
the computer:
- edu
- A U.S. educational institution. Other common endings for
domain names are com (a commercial organization), org (a non-profit
organization), and gov (a government organization).
- uga
- Identifies the University of Georgia subdomain. All
computers at UGA that are on the Internet can register to use a name ending in
"uga.edu."
- gactr
- Identifies the University of Georgia's Center for Continuing
Education.
- www
- A specific computer -- "www" is a common name for
World-Wide Web servers.
- http://www.jvlnet.com/support/www/urls.htm
- The last part of the URL specifies the fully-pathed
filename for this page. "Fully pathed" means that the name tells what
directory the file is stored in on the web server's hard disk drive (and if necessary what
directory that directory is in, and so on). In this example, the file for this page is
"urls.html" (the extension indicates that it is a text file in Hypertext Markup
Language), and it is located in a directory called "Exploring."
Sometimes you will see a domain name followed by a single slash (for
example, http://www.jvlnet.com/). Entering this URL will retrieve the home page for that
web server. Leaving off this slash sometimes produces an error.
URLs may seem long and cumbersome, but each part is
necessary. When you consider that a URL tells exactly where the file is and how to get it,
it's worth all that typing!
To see the URL for the current page in Navigator, make
sure that "Show Location" is checked in the Options menu. This displays the URL
in a box underneath the buttons.
You can type a URL into this box and hit the Return key to
go to that page. In Windows or on the Macintosh, you can also use the cut, copy, and paste
operations to enter a URL. For example, if you are using a Mac or Windows e-mail program,
you can use the mouse to select and copy a URL from the body of a mail message, then
switch to Navigator and paste it into the Location box.
Another way to do the same thing is by clicking on the Open
button, which will present a dialog box in which you can type or paste a URL.
A feature which may not work in other browsers: you can
leave off the "http://" part of the URL for a web page in the Location box or
Open dialogue.
Often you can guess a URL that will get you into the
neighborhood of useful information. Most corporations with World-Wide Web servers use a
"canonical address" in this format:
www.NameOfCorporation.com
For example, if you wanted information about Sony products,
you could look for "http://www.sony.com/". Try it!
If you have trouble retrieving a file, there are
several possible reasons.
- URL problems
- The most common reason for a URL to fail is a typo. Look at
it closely and see if anything is misspelled. A URL can't contain blank spaces. The URL
should end either with the name of a file or with a final /.
It's not unusual to receive an error message "404, File Not Found."
This means the web server could not find a file matching that URL. Sometimes this is a
temporary condition (for example, the manager of the web server may be editing or
replacing the file), so try again later.
- Network problems
- Another common source of trouble is the network through
which you are accessing the URL. The response time of a web server depends on many
factors, including how busy it is, how busy the network is, and how much bandwidth is
available. If a page is loading too slowly, or if you get an error message indicating that
the server is too busy to accept new connections, try again later.
Sometimes your browser will report an error related to a web
server's domain name. The web browser relies on the name servers specified in your
computer's TCP/IP software to translate domain names into a numerical form more suitable
for the limited understanding of network routers. (For example, the domain name
www.gactr.uga.edu translates into the less catchy numeral form 128.192.37.88.) Again, try
later. If domain name problems persist, ask your JVLNET Support Team to help you check
your TCP/IP settings.
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