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| author | André Malo <nd@apache.org> | 2003-04-05 02:58:03 +0000 |
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| committer | André Malo <nd@apache.org> | 2003-04-05 02:58:03 +0000 |
| commit | 558a1d5a03bce706b20758ea4d0f45a746c89a13 (patch) | |
| tree | d6b82602bf96f9862afdcfa8a015ba1cca00d479 /docs | |
| parent | 4892bdca8aa84e82a2ff5c12d79a9aebc58a9b26 (diff) | |
| download | httpd-558a1d5a03bce706b20758ea4d0f45a746c89a13.tar.gz | |
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git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99229 13f79535-47bb-0310-9956-ffa450edef68
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| -rw-r--r-- | docs/manual/developer/hooks.html | 199 | ||||
| -rw-r--r-- | docs/manual/developer/hooks.html.en | 4 |
2 files changed, 2 insertions, 201 deletions
diff --git a/docs/manual/developer/hooks.html b/docs/manual/developer/hooks.html deleted file mode 100644 index f7a5575d16..0000000000 --- a/docs/manual/developer/hooks.html +++ /dev/null @@ -1,199 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" - "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> - -<html xmlns="http://www.w3.org/1999/xhtml"> - <head> - <meta name="generator" content="HTML Tidy, see www.w3.org" /> - - <title>Apache 2.0 Hook Functions</title> - </head> - <!-- Background white, links blue (unvisited), navy (visited), red (active) --> - - <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" - vlink="#000080" alink="#FF0000"> - <!--#include virtual="header.html" --> - - <h1 align="center">Apache Hook Functions</h1> - - <p>In general, a hook function is one that Apache will call at - some point during the processing of a request. Modules can - provide functions that are called, and specify when they get - called in comparison to other modules.</p> - - <h2>Creating a hook function</h2> - - <p>In order to create a new hook, four things need to be - done:</p> - - <h3>Declare the hook function</h3> - - <p>Use the AP_DECLARE_HOOK macro, which needs to be given the - return type of the hook function, the name of the hook, and the - arguments. For example, if the hook returns an <tt>int</tt> and - takes a <tt>request_rec *</tt> and an <tt>int</tt> and is - called "do_something", then declare it like this:</p> - <tt>AP_DECLARE_HOOK(int,do_something,(request_rec *r,int - n))</tt> - - <p>This should go in a header which modules will include if - they want to use the hook.</p> - - <h3>Create the hook structure</h3> - - <p>Each source file that exports a hook has a private structure - which is used to record the module functions that use the hook. - This is declared as follows:</p> -<pre> -APR_HOOK_STRUCT( - APR_HOOK_LINK(do_something) - ... - ) -</pre> - - <h3>Implement the hook caller</h3> - - <p>The source file that exports the hook has to implement a - function that will call the hook. There are currently three - possible ways to do this. In all cases, the calling function is - called <tt>ap_run_<i>hookname</i>()</tt>.</p> - - <h4>Void hooks</h4> - - <p>If the return value of a hook is <tt>void</tt>, then all the - hooks are called, and the caller is implemented like this:</p> - <tt>AP_IMPLEMENT_HOOK_VOID(do_something,(request_rec *r,int - n),(r,n))</tt> - - <p>The second and third arguments are the dummy argument - declaration and the dummy arguments as they will be used when - calling the hook. In other words, this macro expands to - something like this:</p> -<pre> -void ap_run_do_something(request_rec *r,int n) -{ - ... - do_something(r,n); -} -</pre> - - <h4>Hooks that return a value</h4> - - <p>If the hook returns a value, then it can either be run until - the first hook that does something interesting, like so:</p> - <tt>AP_IMPLEMENT_HOOK_RUN_FIRST(int,do_something,(request_rec - *r,int n),(r,n),DECLINED)</tt> - - <p>The first hook that <i>doesn't</i> return <tt>DECLINED</tt> - stops the loop and its return value is returned from the hook - caller. Note that <tt>DECLINED</tt> is the tradition Apache - hook return meaning "I didn't do anything", but it can be - whatever suits you.</p> - - <p>Alternatively, all hooks can be run until an error occurs. - This boils down to permitting <i>two</i> return values, one of - which means "I did something, and it was OK" and the other - meaning "I did nothing". The first function that returns a - value other than one of those two stops the loop, and its - return is the return value. Declare these like so:</p> - <tt>AP_IMPLEMENT_HOOK_RUN_ALL(int,do_something,(request_rec - *r,int n),(r,n),OK,DECLINED)</tt> - - <p>Again, <tt>OK</tt> and <tt>DECLINED</tt> are the traditional - values. You can use what you want.</p> - - <h3>Call the hook callers</h3> - - <p>At appropriate moments in the code, call the hook caller, - like so:</p> -<pre> - int n,ret; - request_rec *r; - - ret=ap_run_do_something(r,n); -</pre> - - <h2>Hooking the hook</h2> - - <p>A module that wants a hook to be called needs to do two - things.</p> - - <h3>Implement the hook function</h3> - - <p>Include the appropriate header, and define a static function - of the correct type:</p> -<pre> -static int my_something_doer(request_rec *r,int n) -{ - ... - return OK; -} -</pre> - - <h3>Add a hook registering function</h3> - - <p>During initialisation, Apache will call each modules hook - registering function, which is included in the module - structure:</p> -<pre> -static void my_register_hooks() -{ - ap_hook_do_something(my_something_doer,NULL,NULL,HOOK_MIDDLE); -} - -mode MODULE_VAR_EXPORT my_module = -{ - ... - my_register_hooks /* register hooks */ -}; -</pre> - - <h3>Controlling hook calling order</h3> - - <p>In the example above, we didn't use the three arguments in - the hook registration function that control calling order. - There are two mechanisms for doing this. The first, rather - crude, method, allows us to specify roughly where the hook is - run relative to other modules. The final argument control this. - There are three possible values:</p> -<pre> -HOOK_FIRST -HOOK_MIDDLE -HOOK_LAST -</pre> - - <p>All modules using any particular value may be run in any - order relative to each other, but, of course, all modules using - <tt>HOOK_FIRST</tt> will be run before <tt>HOOK_MIDDLE</tt> - which are before <tt>HOOK_LAST</tt>. Modules that don't care - when they are run should use <tt>HOOK_MIDDLE</tt>. <i>(I spaced - these out so people could do stuff like <tt>HOOK_FIRST-2</tt> - to get in slightly earlier, but is this wise? - Ben)</i></p> - - <p>Note that there are two more values, - <tt>HOOK_REALLY_FIRST</tt> and <tt>HOOK_REALLY_LAST</tt>. These - should only be used by the hook exporter.</p> - - <p>The other method allows finer control. When a module knows - that it must be run before (or after) some other modules, it - can specify them by name. The second (third) argument is a - NULL-terminated array of strings consisting of the names of - modules that must be run before (after) the current module. For - example, suppose we want "mod_xyz.c" and "mod_abc.c" to run - before we do, then we'd hook as follows:</p> -<pre> -static void register_hooks() -{ - static const char * const aszPre[]={ "mod_xyz.c", "mod_abc.c", NULL }; - - ap_hook_do_something(my_something_doer,aszPre,NULL,HOOK_MIDDLE); -} -</pre> - - <p>Note that the sort used to achieve this is stable, so - ordering set by <tt>HOOK_<i>ORDER</i></tt> is preserved, as far - as is possible.</p> - <i>Ben Laurie, 15th August 1999</i> - <!--#include virtual="footer.html" --> - </body> -</html> - diff --git a/docs/manual/developer/hooks.html.en b/docs/manual/developer/hooks.html.en index 120d90809f..86eb4a1ef5 100644 --- a/docs/manual/developer/hooks.html.en +++ b/docs/manual/developer/hooks.html.en @@ -12,11 +12,11 @@ <link href="../images/favicon.ico" rel="shortcut icon" /></head> <body id="manual-page"><div id="page-header"> <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> -<p class="apache">Apache HTTP Server Version 2.1</p> +<p class="apache">Apache HTTP Server Version 2.0</p> <img alt="" src="../images/feather.gif" /></div> <div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> <div id="path"> -<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs-project/">Documentation</a> > <a href="../">Version 2.1</a></div><div id="page-content"><div id="preamble"><h1>Apache 2.0 Hook Functions</h1> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs-project/">Documentation</a> > <a href="../">Version 2.0</a></div><div id="page-content"><div id="preamble"><h1>Apache 2.0 Hook Functions</h1> <div class="warning"><h3>Warning</h3> <p>This document is still in development and may be partially out of date.</p> |