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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP Application Layer Addressing: Uniform Resource Identifiers, Locators and Names (URIs, URLs and URNs)                 9  Uniform Resource Locators (URLs)

URL Relative Syntax and Base URLs 1 2 3 4 URL Obscuration, Obfuscation and General Trickery

Reasons Why Long URLs are Common

The point that many elements in URL syntax are optional is important. The majority of the time, most of these optional parts are omitted, which makes URLs much simpler in practical use than they are “on paper”. For example, even though an HTTP URL theoretically contains a user name, password, host, port, path, query and bookmark, most URLs use only a host name and a path. This is what helps keep URLs short and easy to use.

Despite this, you will still find some rather long URLs used on the Internet. Here are some of the most common reasons why.

Some people don't realize that long host names are hard to remember. If you run the “Super Auto Body Shop & Pizza Parlor”, having a Web site called “www.superauto.com” will make it easier for your customers to find you than trying to register “www.superautobodyshopandpizza.com”. Yet DNS names of 15, 20 or even more characters are surprisingly common.

Similarly, short file names are better than long ones, and again, many people don't think about this before putting files on the Internet, which makes things more difficult for those who must access them.

URLs have a mechanism for dealing with “unsafe” characters, but it makes them longer and harder to decipher. Suppose you have a file named:

“{ABC Corp} budget; draft #3; third quarter 2004.htm”

The URL for this will have to be:

“%7BABC%20Corp%7D%20budget%3B%20draft%20%233%3B%20third%20quarter%202004.htm”

The original long file name was readable, but the URL is a mess because of the special character encodings.

Naming the file “ABC budget draft 3, 3Q2004.htm” would be a better choice, and still includes enough information to be understandable. Even better, you could replace the spaces with underscores, to avoid the need for “%20”s entirely: “ABC_budget_draft 3,_3Q2004.htm”.

In HTTP URLs, the syntax for specifying a query (following a question mark character) is often used to allow a Web browser to send various types of information to a Web server, especially parameters for interactive queries. These parameter strings can get quite lengthy. For example, I typed in a query to the great Web search engine Google to find recipes for potato salad. This is what the URL for one of the recipe files looks like:

“http://groups.google.com/groups?q=%22potato+salad%22&hl=en&lr=&ie=UTF-8&safe=off&selm=B826FB57.89C0%25sbrooks%40ev1.net&rnum=2”.

Almost all of that consists of parameters that tell the Google server exactly what document I want based on my query. It is necessary, but still cumbersome.

URL Relative Syntax and Base URLs 1 2 3 4 URL Obscuration, Obfuscation and General Trickery