Rewrite engine

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A rewrite engine is software that modifies a web URL's appearance (URL rewriting). Rewritten URL's (sometimes known as short or fancy URL's) are used to provide shorter and more relevant-looking links to web pages. The technique adds a degree of separation between the files used to generate a web page and the URL that is presented to the world.


[edit] Examples

This URL contains query string parameters that encode blog entry dates

but can be altered to give the user a clear idea of what he or she is going to see 

The second address also allows the user to change the URL to see all postings available in December, simply by removing the text encoding the day '10', and thereby saving having to navigate the GUI.

Another example might be changing


The benefits of a rewrite engine are[1]:

  • Making website URLs more user friendly
  • Preventing undesired "inline linking"
  • Not exposing the inner workings of a web site's address to visitors
  • The URLs of pages on the web site can be kept even if the underlying technology used to serve them is changed

Known drawbacks:

  • In some cases, for example if user modifies URL to get specified data the rewrite engine may hinder from querying. See below example:
Which is a month and which is a day?
The query like that is more useful than:

[edit] Java

In Java, the term "URL rewriting" sometimes describes a Web Application Server adding a session id to a URL when cookies are not supported (e.g. "index.jsp" is rewritten to "index.jsp;jsessionid=xyz" when the links are drawn in an HTML page).

[edit] Modern web frameworks

Recent generations of web frameworks usually include URL rewriting: Ruby on Rails has built-in URL rewriting via Routes[2], Django uses a regular-expressions based system[3], Java's Stripes Framework used to require a third-party extension[4] but integrated the module in the core distribution with Stripes 1.5.[5]

From a software development perspective, URL rewriting can aid in code modularization and control flow [6], making it a useful feature of modern web frameworks.

[edit] See also

[edit] Notes

  1. ^ Many of these only apply to HTTP servers whose default behavior is to map URLs to filesystem entities (i.e. files and directories); certain environments, such as many HTTP application server platforms, make this irrelevant.
  2. ^ Routes
  3. ^ Django URLconf
  4. ^ Stripes' "Clean Urls" extension
  5. ^ clean urls in Stripes 1.5
  6. ^ DocForge: Clean URL

[edit] External links

[edit] Apache

[edit] IIS (Microsoft Internet Information Services)

[edit] Zeus Web Server

Note: Unlike Apache, entering rewrite rules in an .htaccess file will not work. They must be entered in Zeus' proprietary Request Rewrite scripting language through the zeus server's admin panel, which creates a rewrite.script file and installs it into the server. Unless you have access to the main server administration interface, you will need to ask your hosting provider to implement your rule.

[edit] Java Platform, Enterprise Edition (Java EE) Servlet container servers (Apache Tomcat, Resin, Orion etc)

  • HttpRedirectFilter (open source)
  • UrlRewriteFilter (open source - BSD) - allows you to rewrite URLs before they get to your code. Supports XML or mod_rewrite style config.
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