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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

Uniform Resource Locators (URLs) are the most ubiquitous form of resource addressing for some very good reasons: they represent a simple, convenient and easy-to-understand way of finding documents. Popularized by their use on the World Wide Web, URLs can now be seen in everything from electronic document lists to television commercials, a testament to their universality and ease of use.

At least, this is true most of the time!

When URLs work, they work very well. Unfortunately, there are also some concerns that arise with respect to how URLs are used. Both accidental and intentional misuse of URLs occurs on a regular basis. Part of why I have devoted so much effort to describing URLs is that most people don't really understand how they work, and this is part of why problems occur.

Many of the issues with URLs are directly due to the related matters of length and complexity. URLs work best when they are short and simple, so it is clear what they are about and so they are easy to manipulate. For example, “http://www.ibm.com” is recognizable to almost everyone as the World Wide Web (WWW) site of the International Business Machines Corporation (IBM). Similarly, you can probably figure out what this URL does without any explanation: “ftp://www.somecomputercompany.com/drivers/videodrivers.zip”.

However, as we have seen earlier in this section, URLs can be much more complex. In particular, the common Internet syntax used by protocols such as HTTP and FTP is extremely flexible, containing a large number of optional elements that can be used when required to provide the information necessary for a particular resource access.

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