Rewrite-Engine

A rewrite engine ( " rewrite " of english rewrite, and engine, "machine" ) makes it to a Web server requests directed to rewrite internally or externally forwarded. For the Apache Web server software module mod_rewrite done this task. Other Web servers like Microsoft IIS, nginx, lighttpd or Hiawatha web server offer similar features.

Was created this functionality in order to provide an independent internal factors addressing scheme available to the outside can, so that for example even the URLs remain valid when changing the file hierarchy. One speaks in this case of permanent links.

Allow the rewrite engines to make the address redirection of additional conditions in addition to the requested URL depending, for example by referencing the URL, the user agent ID or the IP address of the requesting client. In this way, for example, domain redirects or cloaking can be realized.

Sample application

Rewrite engines are often used to make resources with dynamic URLs can be contacted at alternative addresses.

The resource with the internal, technically related address

So for example, at the following address reachable

Seemingly static addresses are then outwards instead of dynamic, parameterized addresses. This is useful as a short, self-explanatory addresses easier to remember than most readable and are generally classified as trustworthy. One speaks in this case of Clean URLs.

A possible implementation of the use case shown for the Apache module mod_rewrite is in the server context, for example, using a regular expression: