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Posted to cvs@httpd.apache.org by rb...@apache.org on 2005/03/17 02:47:46 UTC
svn commit: r157850 - httpd/httpd/trunk/docs/manual/mod/mod_rewrite.html.en
httpd/httpd/trunk/docs/manual/mod/mod_rewrite.xml
Author: rbowen
Date: Wed Mar 16 17:47:45 2005
New Revision: 157850
URL: http://svn.apache.org/viewcvs?view=rev&rev=157850
Log:
Moved some of the gorey details out of the module reference doc and into
the supporting documentation. Might want to move some more, too. Haven't
decided yet.
Modified:
httpd/httpd/trunk/docs/manual/mod/mod_rewrite.html.en
httpd/httpd/trunk/docs/manual/mod/mod_rewrite.xml
Modified: httpd/httpd/trunk/docs/manual/mod/mod_rewrite.html.en
URL: http://svn.apache.org/viewcvs/httpd/httpd/trunk/docs/manual/mod/mod_rewrite.html.en?view=diff&r1=157849&r2=157850
==============================================================================
--- httpd/httpd/trunk/docs/manual/mod/mod_rewrite.html.en (original)
+++ httpd/httpd/trunk/docs/manual/mod/mod_rewrite.html.en Wed Mar 16 17:47:45 2005
@@ -31,31 +31,6 @@
<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 1.3 and later</td></tr></table>
<h3>Summary</h3>
- <blockquote>
- <p>``The great thing about mod_rewrite is it gives you
- all the configurability and flexibility of Sendmail.
- The downside to mod_rewrite is that it gives you all
- the configurability and flexibility of Sendmail.''</p>
-
- <p class="cite">-- <cite>Brian Behlendorf</cite><br />
- Apache Group</p>
-
- </blockquote>
-
- <blockquote>
- <p>`` Despite the tons of examples and docs,
- mod_rewrite is voodoo. Damned cool voodoo, but still
- voodoo. ''</p>
-
- <p class="cite">-- <cite>Brian Moore</cite><br />
- bem@news.cmc.net</p>
-
- </blockquote>
-
-
- <p>Welcome to mod_rewrite, the Swiss Army Knife of URL
- manipulation!</p>
-
<p>This module uses a rule-based rewriting engine (based on a
regular-expression parser) to rewrite requested URLs on the
fly. It supports an unlimited number of rules and an
@@ -75,20 +50,8 @@
sub-processing, external request redirection or even to an
internal proxy throughput.</p>
- <p>But all this functionality and flexibility has its
- drawback: complexity. So don't expect to understand this
- entire module in just one day.</p>
-
- <p>This module was invented and originally written in April
- 1996 and gifted exclusively to the The Apache Group in July 1997
- by</p>
-
- <p class="indent">
- <a href="http://www.engelschall.com/"><code>Ralf S.
- Engelschall</code></a><br />
- <a href="mailto:rse@engelschall.com"><code>rse@engelschall.com</code></a><br />
- <a href="http://www.engelschall.com/"><code>www.engelschall.com</code></a>
- </p>
+ <p>Further details, discussion, and examples, are provided in the
+ <a href="../rewrite/">detailed mod_rewrite documentation</a>.</p>
</div>
<div id="quickview"><h3 class="directives">Directives</h3>
<ul id="toc">
@@ -104,138 +67,14 @@
</ul>
<h3>Topics</h3>
<ul id="topics">
-<li><img alt="" src="../images/down.gif" /> <a href="#Internal">Internal Processing</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#quoting">Quoting Special Characters</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#InternalBackRefs">Regex Back-Reference Availability</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#EnvVar">Environment Variables</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#Solutions">Practical Solutions</a></li>
</ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
-<h2><a name="Internal" id="Internal">Internal Processing</a></h2>
-
- <p>The internal processing of this module is very complex but
- needs to be explained once even to the average user to avoid
- common mistakes and to let you exploit its full
- functionality.</p>
-
-<h3><a name="InternalAPI" id="InternalAPI">API Phases</a></h3>
-
- <p>First you have to understand that when Apache processes a
- HTTP request it does this in phases. A hook for each of these
- phases is provided by the Apache API. Mod_rewrite uses two of
- these hooks: the URL-to-filename translation hook which is
- used after the HTTP request has been read but before any
- authorization starts and the Fixup hook which is triggered
- after the authorization phases and after the per-directory
- config files (<code>.htaccess</code>) have been read, but
- before the content handler is activated.</p>
-
- <p>So, after a request comes in and Apache has determined the
- corresponding server (or virtual server) the rewriting engine
- starts processing of all mod_rewrite directives from the
- per-server configuration in the URL-to-filename phase. A few
- steps later when the final data directories are found, the
- per-directory configuration directives of mod_rewrite are
- triggered in the Fixup phase. In both situations mod_rewrite
- rewrites URLs either to new URLs or to filenames, although
- there is no obvious distinction between them. This is a usage
- of the API which was not intended to be this way when the API
- was designed, but as of Apache 1.x this is the only way
- mod_rewrite can operate. To make this point more clear
- remember the following two points:</p>
-
- <ol>
- <li>Although mod_rewrite rewrites URLs to URLs, URLs to
- filenames and even filenames to filenames, the API
- currently provides only a URL-to-filename hook. In Apache
- 2.0 the two missing hooks will be added to make the
- processing more clear. But this point has no drawbacks for
- the user, it is just a fact which should be remembered:
- Apache does more in the URL-to-filename hook than the API
- intends for it.</li>
-
- <li>
- Unbelievably mod_rewrite provides URL manipulations in
- per-directory context, <em>i.e.</em>, within
- <code>.htaccess</code> files, although these are reached
- a very long time after the URLs have been translated to
- filenames. It has to be this way because
- <code>.htaccess</code> files live in the filesystem, so
- processing has already reached this stage. In other
- words: According to the API phases at this time it is too
- late for any URL manipulations. To overcome this chicken
- and egg problem mod_rewrite uses a trick: When you
- manipulate a URL/filename in per-directory context
- mod_rewrite first rewrites the filename back to its
- corresponding URL (which is usually impossible, but see
- the <code>RewriteBase</code> directive below for the
- trick to achieve this) and then initiates a new internal
- sub-request with the new URL. This restarts processing of
- the API phases.
-
- <p>Again mod_rewrite tries hard to make this complicated
- step totally transparent to the user, but you should
- remember here: While URL manipulations in per-server
- context are really fast and efficient, per-directory
- rewrites are slow and inefficient due to this chicken and
- egg problem. But on the other hand this is the only way
- mod_rewrite can provide (locally restricted) URL
- manipulations to the average user.</p>
- </li>
- </ol>
-
- <p>Don't forget these two points!</p>
-
-
-<h3><a name="InternalRuleset" id="InternalRuleset">Ruleset Processing</a></h3>
-
- <p>Now when mod_rewrite is triggered in these two API phases, it
- reads the configured rulesets from its configuration
- structure (which itself was either created on startup for
- per-server context or during the directory walk of the Apache
- kernel for per-directory context). Then the URL rewriting
- engine is started with the contained ruleset (one or more
- rules together with their conditions). The operation of the
- URL rewriting engine itself is exactly the same for both
- configuration contexts. Only the final result processing is
- different. </p>
-
- <p>The order of rules in the ruleset is important because the
- rewriting engine processes them in a special (and not very
- obvious) order. The rule is this: The rewriting engine loops
- through the ruleset rule by rule (<code class="directive"><a href="#rewriterule">RewriteRule</a></code> directives) and
- when a particular rule matches it optionally loops through
- existing corresponding conditions (<code>RewriteCond</code>
- directives). For historical reasons the conditions are given
- first, and so the control flow is a little bit long-winded. See
- Figure 1 for more details.</p>
-<p class="figure">
- <img src="../images/mod_rewrite_fig1.gif" width="428" height="385" alt="[Needs graphics capability to display]" /><br />
- <dfn>Figure 1:</dfn>The control flow through the rewriting ruleset
-</p>
- <p>As you can see, first the URL is matched against the
- <em>Pattern</em> of each rule. When it fails mod_rewrite
- immediately stops processing this rule and continues with the
- next rule. If the <em>Pattern</em> matches, mod_rewrite looks
- for corresponding rule conditions. If none are present, it
- just substitutes the URL with a new value which is
- constructed from the string <em>Substitution</em> and goes on
- with its rule-looping. But if conditions exist, it starts an
- inner loop for processing them in the order that they are
- listed. For conditions the logic is different: we don't match
- a pattern against the current URL. Instead we first create a
- string <em>TestString</em> by expanding variables,
- back-references, map lookups, <em>etc.</em> and then we try
- to match <em>CondPattern</em> against it. If the pattern
- doesn't match, the complete set of conditions and the
- corresponding rule fails. If the pattern matches, then the
- next condition is processed until no more conditions are
- available. If all conditions match, processing is continued
- with the substitution of the URL with
- <em>Substitution</em>.</p>
-
-
-
-<h3><a name="quoting" id="quoting">Quoting Special Characters</a></h3>
+<h2><a name="quoting" id="quoting">Quoting Special Characters</a></h2>
<p>As of Apache 1.3.20, special characters in
<em>TestString</em> and <em>Substitution</em> strings can be
@@ -245,9 +84,9 @@
dollar-sign character in a <em>Substitution</em> string by
using '<code>\$</code>'; this keeps mod_rewrite from trying
to treat it as a backreference.</p>
-
-
-<h3><a name="InternalBackRefs" id="InternalBackRefs">Regex Back-Reference Availability</a></h3>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="InternalBackRefs" id="InternalBackRefs">Regex Back-Reference Availability</a></h2>
<p>One important thing here has to be remembered: Whenever you
use parentheses in <em>Pattern</em> or in one of the
@@ -267,7 +106,6 @@
reading the following documentation of the available
directives.</p>
-
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="EnvVar" id="EnvVar">Environment Variables</a></h2>
@@ -297,11 +135,11 @@
<div class="section">
<h2><a name="Solutions" id="Solutions">Practical Solutions</a></h2>
- <p>We also have an <a href="../misc/rewriteguide.html">URL
- Rewriting Guide</a> available, which provides a collection of
- practical solutions for URL-based problems. There you can
- find real-life rulesets and additional information about
- mod_rewrite.</p>
+ <p>For numerous examples of common, and not-so-common, uses for
+ mod_rewrite, see the <a href="../rewrite/rewrite_guide.html">Rewrite
+ Guide</a>, and the <a href="../rewrite/rewrite_guide_advanced.html">Advanced Rewrite
+ Guide</a> documents.</p>
+
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="RewriteBase" id="RewriteBase">RewriteBase</a> <a name="rewritebase" id="rewritebase">Directive</a></h2>
Modified: httpd/httpd/trunk/docs/manual/mod/mod_rewrite.xml
URL: http://svn.apache.org/viewcvs/httpd/httpd/trunk/docs/manual/mod/mod_rewrite.xml?view=diff&r1=157849&r2=157850
==============================================================================
--- httpd/httpd/trunk/docs/manual/mod/mod_rewrite.xml (original)
+++ httpd/httpd/trunk/docs/manual/mod/mod_rewrite.xml Wed Mar 16 17:47:45 2005
@@ -33,31 +33,6 @@
<compatibility>Available in Apache 1.3 and later</compatibility>
<summary>
- <blockquote>
- <p>``The great thing about mod_rewrite is it gives you
- all the configurability and flexibility of Sendmail.
- The downside to mod_rewrite is that it gives you all
- the configurability and flexibility of Sendmail.''</p>
-
- <p class="cite">-- <cite>Brian Behlendorf</cite><br />
- Apache Group</p>
-
- </blockquote>
-
- <blockquote>
- <p>`` Despite the tons of examples and docs,
- mod_rewrite is voodoo. Damned cool voodoo, but still
- voodoo. ''</p>
-
- <p class="cite">-- <cite>Brian Moore</cite><br />
- bem@news.cmc.net</p>
-
- </blockquote>
-
-
- <p>Welcome to mod_rewrite, the Swiss Army Knife of URL
- manipulation!</p>
-
<p>This module uses a rule-based rewriting engine (based on a
regular-expression parser) to rewrite requested URLs on the
fly. It supports an unlimited number of rules and an
@@ -77,151 +52,10 @@
sub-processing, external request redirection or even to an
internal proxy throughput.</p>
- <p>But all this functionality and flexibility has its
- drawback: complexity. So don't expect to understand this
- entire module in just one day.</p>
-
- <p>This module was invented and originally written in April
- 1996 and gifted exclusively to the The Apache Group in July 1997
- by</p>
-
- <p class="indent">
- <a href="http://www.engelschall.com/"><code>Ralf S.
- Engelschall</code></a><br />
- <a
- href="mailto:rse@engelschall.com"><code>rse@engelschall.com</code></a><br />
- <a
- href="http://www.engelschall.com/"><code>www.engelschall.com</code></a>
- </p>
+ <p>Further details, discussion, and examples, are provided in the
+ <a href="../rewrite/">detailed mod_rewrite documentation</a>.</p>
</summary>
-<section id="Internal"><title>Internal Processing</title>
-
- <p>The internal processing of this module is very complex but
- needs to be explained once even to the average user to avoid
- common mistakes and to let you exploit its full
- functionality.</p>
-
-<section id="InternalAPI"><title>API Phases</title>
-
- <p>First you have to understand that when Apache processes a
- HTTP request it does this in phases. A hook for each of these
- phases is provided by the Apache API. Mod_rewrite uses two of
- these hooks: the URL-to-filename translation hook which is
- used after the HTTP request has been read but before any
- authorization starts and the Fixup hook which is triggered
- after the authorization phases and after the per-directory
- config files (<code>.htaccess</code>) have been read, but
- before the content handler is activated.</p>
-
- <p>So, after a request comes in and Apache has determined the
- corresponding server (or virtual server) the rewriting engine
- starts processing of all mod_rewrite directives from the
- per-server configuration in the URL-to-filename phase. A few
- steps later when the final data directories are found, the
- per-directory configuration directives of mod_rewrite are
- triggered in the Fixup phase. In both situations mod_rewrite
- rewrites URLs either to new URLs or to filenames, although
- there is no obvious distinction between them. This is a usage
- of the API which was not intended to be this way when the API
- was designed, but as of Apache 1.x this is the only way
- mod_rewrite can operate. To make this point more clear
- remember the following two points:</p>
-
- <ol>
- <li>Although mod_rewrite rewrites URLs to URLs, URLs to
- filenames and even filenames to filenames, the API
- currently provides only a URL-to-filename hook. In Apache
- 2.0 the two missing hooks will be added to make the
- processing more clear. But this point has no drawbacks for
- the user, it is just a fact which should be remembered:
- Apache does more in the URL-to-filename hook than the API
- intends for it.</li>
-
- <li>
- Unbelievably mod_rewrite provides URL manipulations in
- per-directory context, <em>i.e.</em>, within
- <code>.htaccess</code> files, although these are reached
- a very long time after the URLs have been translated to
- filenames. It has to be this way because
- <code>.htaccess</code> files live in the filesystem, so
- processing has already reached this stage. In other
- words: According to the API phases at this time it is too
- late for any URL manipulations. To overcome this chicken
- and egg problem mod_rewrite uses a trick: When you
- manipulate a URL/filename in per-directory context
- mod_rewrite first rewrites the filename back to its
- corresponding URL (which is usually impossible, but see
- the <code>RewriteBase</code> directive below for the
- trick to achieve this) and then initiates a new internal
- sub-request with the new URL. This restarts processing of
- the API phases.
-
- <p>Again mod_rewrite tries hard to make this complicated
- step totally transparent to the user, but you should
- remember here: While URL manipulations in per-server
- context are really fast and efficient, per-directory
- rewrites are slow and inefficient due to this chicken and
- egg problem. But on the other hand this is the only way
- mod_rewrite can provide (locally restricted) URL
- manipulations to the average user.</p>
- </li>
- </ol>
-
- <p>Don't forget these two points!</p>
-</section>
-
-<section id="InternalRuleset"><title>Ruleset Processing</title>
-
- <p>Now when mod_rewrite is triggered in these two API phases, it
- reads the configured rulesets from its configuration
- structure (which itself was either created on startup for
- per-server context or during the directory walk of the Apache
- kernel for per-directory context). Then the URL rewriting
- engine is started with the contained ruleset (one or more
- rules together with their conditions). The operation of the
- URL rewriting engine itself is exactly the same for both
- configuration contexts. Only the final result processing is
- different. </p>
-
- <p>The order of rules in the ruleset is important because the
- rewriting engine processes them in a special (and not very
- obvious) order. The rule is this: The rewriting engine loops
- through the ruleset rule by rule (<directive
- module="mod_rewrite">RewriteRule</directive> directives) and
- when a particular rule matches it optionally loops through
- existing corresponding conditions (<code>RewriteCond</code>
- directives). For historical reasons the conditions are given
- first, and so the control flow is a little bit long-winded. See
- Figure 1 for more details.</p>
-<p class="figure">
- <img src="../images/mod_rewrite_fig1.gif" width="428"
- height="385" alt="[Needs graphics capability to display]" /><br />
- <dfn>Figure 1:</dfn>The control flow through the rewriting ruleset
-</p>
- <p>As you can see, first the URL is matched against the
- <em>Pattern</em> of each rule. When it fails mod_rewrite
- immediately stops processing this rule and continues with the
- next rule. If the <em>Pattern</em> matches, mod_rewrite looks
- for corresponding rule conditions. If none are present, it
- just substitutes the URL with a new value which is
- constructed from the string <em>Substitution</em> and goes on
- with its rule-looping. But if conditions exist, it starts an
- inner loop for processing them in the order that they are
- listed. For conditions the logic is different: we don't match
- a pattern against the current URL. Instead we first create a
- string <em>TestString</em> by expanding variables,
- back-references, map lookups, <em>etc.</em> and then we try
- to match <em>CondPattern</em> against it. If the pattern
- doesn't match, the complete set of conditions and the
- corresponding rule fails. If the pattern matches, then the
- next condition is processed until no more conditions are
- available. If all conditions match, processing is continued
- with the substitution of the URL with
- <em>Substitution</em>.</p>
-
-</section>
-
<section id="quoting"><title>Quoting Special Characters</title>
<p>As of Apache 1.3.20, special characters in
@@ -256,7 +90,6 @@
directives.</p>
</section>
-</section>
<section id="EnvVar"><title>Environment Variables</title>
@@ -287,13 +120,13 @@
<section id="Solutions"><title>Practical Solutions</title>
- <p>We also have an <a href="../misc/rewriteguide.html">URL
- Rewriting Guide</a> available, which provides a collection of
- practical solutions for URL-based problems. There you can
- find real-life rulesets and additional information about
- mod_rewrite.</p>
-</section>
+ <p>For numerous examples of common, and not-so-common, uses for
+ mod_rewrite, see the <a href="../rewrite/rewrite_guide.html">Rewrite
+ Guide</a>, and the <a
+ href="../rewrite/rewrite_guide_advanced.html">Advanced Rewrite
+ Guide</a> documents.</p>
+</section>
<directivesynopsis>
<name>RewriteEngine</name>