| <?xml version="1.0" encoding="UTF-8" ?> |
| <!DOCTYPE manualpage SYSTEM "./style/manualpage.dtd"> |
| <?xml-stylesheet type="text/xsl" href="./style/manual.en.xsl"?> |
| <!-- $LastChangedRevision$ --> |
| |
| <!-- |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to You under the Apache License, Version 2.0 |
| (the "License"); you may not use this file except in compliance with |
| the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| --> |
| |
| <manualpage metafile="handler.xml.meta"> |
| |
| <title>Apache's Handler Use</title> |
| |
| <summary> |
| <p>This document describes the use of Apache's Handlers.</p> |
| </summary> |
| |
| <section id="definition"> |
| <title>What is a Handler</title> |
| <related> |
| <modulelist> |
| <module>mod_actions</module> |
| <module>mod_asis</module> |
| <module>mod_cgi</module> |
| <module>mod_imagemap</module> |
| <module>mod_info</module> |
| <module>mod_mime</module> |
| <module>mod_negotiation</module> |
| <module>mod_status</module> |
| </modulelist> |
| <directivelist> |
| <directive module="mod_actions">Action</directive> |
| <directive module="mod_mime">AddHandler</directive> |
| <directive module="mod_mime">RemoveHandler</directive> |
| <directive module="core">SetHandler</directive> |
| </directivelist> |
| </related> |
| |
| |
| <p>A "handler" is an internal Apache representation of the |
| action to be performed when a file is called. Generally, files |
| have implicit handlers, based on the file type. Normally, all |
| files are simply served by the server, but certain file types |
| are "handled" separately.</p> |
| |
| <p>Handlers may also be configured explicitly, |
| based on either filename extensions or on location, |
| without relation to file type. This is |
| advantageous both because it is a more elegant solution, and |
| because it also allows for both a type <strong>and</strong> a |
| handler to be associated with a file. (See also <a |
| href="mod/mod_mime.html#multipleext">Files with Multiple |
| Extensions</a>.)</p> |
| |
| <p>Handlers can either be built into the server or included in |
| a module, or they can be added with the <directive |
| module="mod_actions">Action</directive> directive. The |
| built-in handlers in the standard distribution are as |
| follows:</p> |
| |
| <ul> |
| <li><strong>default-handler</strong>: Send the file using the |
| <code>default_handler()</code>, which is the handler used by |
| default to handle static content. (core)</li> |
| |
| <li><strong>send-as-is</strong>: Send file with HTTP headers |
| as is. (<module>mod_asis</module>)</li> |
| |
| <li><strong>cgi-script</strong>: Treat the file as a CGI |
| script. (<module>mod_cgi</module>)</li> |
| |
| <li><strong>imap-file</strong>: Parse as an imagemap rule |
| file. (<module>mod_imagemap</module>)</li> |
| |
| <li><strong>server-info</strong>: Get the server's |
| configuration information. (<module>mod_info</module>)</li> |
| |
| <li><strong>server-status</strong>: Get the server's status |
| report. (<module>mod_status</module>)</li> |
| |
| <li><strong>type-map</strong>: Parse as a type map file for |
| content negotiation. (<module>mod_negotiation</module>)</li> |
| </ul> |
| </section> |
| <section id="examples"> |
| <title>Examples</title> |
| |
| <section id="example1"> |
| <title>Modifying static content using a CGI script</title> |
| |
| <p>The following directives will cause requests for files with |
| the <code>html</code> extension to trigger the launch of the |
| <code>footer.pl</code> CGI script.</p> |
| |
| <highlight language="config"> |
| Action add-footer /cgi-bin/footer.pl |
| AddHandler add-footer .html |
| </highlight> |
| |
| <p>Then the CGI script is responsible for sending the |
| originally requested document (pointed to by the |
| <code>PATH_TRANSLATED</code> environment variable) and making |
| whatever modifications or additions are desired.</p> |
| |
| </section> |
| <section id="example2"> |
| <title>Files with HTTP headers</title> |
| |
| <p>The following directives will enable the |
| <code>send-as-is</code> handler, which is used for files which |
| contain their own HTTP headers. All files in the |
| <code>/web/htdocs/asis/</code> directory will be processed by |
| the <code>send-as-is</code> handler, regardless of their |
| filename extensions.</p> |
| |
| <highlight language="config"> |
| <Directory "/web/htdocs/asis"> |
| SetHandler send-as-is |
| </Directory> |
| </highlight> |
| |
| </section> |
| </section> |
| <section id="programmer"> |
| <title>Programmer's Note</title> |
| |
| <p>In order to implement the handler features, an addition has |
| been made to the <a href="developer/API.html">Apache API</a> that |
| you may wish to make use of. Specifically, a new record has |
| been added to the <code>request_rec</code> structure:</p> |
| |
| <highlight language="c"> |
| char *handler |
| </highlight> |
| |
| <p>If you wish to have your module engage a handler, you need |
| only to set <code>r->handler</code> to the name of the |
| handler at any time prior to the <code>invoke_handler</code> |
| stage of the request. Handlers are implemented as they were |
| before, albeit using the handler name instead of a content |
| type. While it is not necessary, the naming convention for |
| handlers is to use a dash-separated word, with no slashes, so |
| as to not invade the media type name-space.</p> |
| </section> |
| </manualpage> |