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| <title>API Changes in Apache HTTP Server 2.4 since 2.2 - Apache HTTP Server</title> |
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| <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 2.3</p> |
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| <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/">Documentation</a> > <a href="../">Version 2.3</a></div><div id="page-content"><div id="preamble"><h1>API Changes in Apache HTTP Server 2.4 since 2.2</h1> |
| <div class="toplang"> |
| <p><span>Available Languages: </span><a href="../en/developer/new_api_2_4.html" title="English"> en </a></p> |
| </div> |
| |
| <p>This document describes changes to the Apache HTTPD API from |
| version 2.2 to 2.4, that may be of interest to module/application |
| developers and core hacks. At the time of writing, the 2.4 API |
| is not finalised, and this document may serve to highlight |
| points that call for further review.</p> |
| <p>API changes fall into two categories: APIs that are altogether new, |
| and existing APIs that are expanded or changed. The latter are |
| further divided into those where all changes are back-compatible |
| (so existing modules can ignore them), and those that might |
| require attention by maintainers. As with the transition from |
| HTTPD 2.0 to 2.2, existing modules and applications will require |
| recompiling and may call for some attention, but most should not |
| require any substantial updating (although some may be able to |
| take advantage of API changes to offer significant improvements).</p> |
| <p>For the purpose of this document, the API is split according |
| to the public header files. These headers are themselves the |
| reference documentation, and can be used to generate a browsable |
| HTML reference with <code>make docs</code>.</p> |
| </div> |
| <div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#api_changes">Changed APIs</a></li> |
| <li><img alt="" src="../images/down.gif" /> <a href="#upgrading">Specific information on upgrading modules from 2.2</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="api_changes" id="api_changes">Changed APIs</a></h2> |
| |
| |
| <h3><a name="ap_expr" id="ap_expr">ap_expr (NEW!)</a></h3> |
| |
| <p>Introduces a new API to parse and evaluate boolean and algebraic |
| expressions, including provision for a standard syntax and |
| customised variants.</p> |
| |
| |
| <h3><a name="ap_listen" id="ap_listen">ap_listen (changed; back-compatible)</a></h3> |
| |
| <p>Introduces new API to enable apache child processes to serve different purposes.</p> |
| |
| |
| <h3><a name="ap_mpm" id="ap_mpm">ap_mpm (changed)</a></h3> |
| |
| <p><code>ap_mpm_run</code> is replaced by a new <code>mpm</code> hook. |
| Also <code>ap_graceful_stop_signalled</code> is lost, and |
| <code>ap_mpm_register_timed_callback</code> is new.</p> |
| |
| |
| <h3><a name="ap_regex" id="ap_regex">ap_regex (changed)</a></h3> |
| |
| <p>In addition to the existing regexp wrapper, a new higher-level API |
| <code>ap_rxplus</code> is now provided. This provides the capability to |
| compile Perl-style expressions like <code>s/regexp/replacement/flags</code> |
| and to execute them against arbitrary strings. Support for regexp |
| backreference.</p> |
| |
| |
| <h3><a name="ap_slotmem" id="ap_slotmem">ap_slotmem (NEW!)</a></h3> |
| |
| <p>Introduces an API for modules to allocate and manage memory slots |
| (normally) for shared memory.</p> |
| |
| |
| <h3><a name="ap_socache" id="ap_socache">ap_socache (NEW!)</a></h3> |
| |
| <p>API to manage a shared object cache.</p> |
| |
| |
| <h3><a name="heartbeat" id="heartbeat">heartbeat (NEW!)</a></h3> |
| |
| <p>common structures for heartbeat modules (should this be public API?)</p> |
| |
| |
| <h3><a name="http_config" id="http_config">http_config (changed)</a></h3> |
| |
| <ul> |
| <li>Introduces per-module, per-directory loglevels, including macro wrappers.</li> |
| <li>New AP_DECLARE_MODULE macro to declare all modules.</li> |
| <li>New APLOG_USE_MODULE macro necessary for per-module loglevels in |
| multi-file modules.</li> |
| <li>New API to retain data across module unload/load</li> |
| <li>New check_config hook</li> |
| <li>New ap_process_fnmatch_configs() to process wildcards</li> |
| <li>Change ap_configfile_t, ap_cfg_getline(), ap_cfg_getc() to return error |
| code, new ap_pcfg_strerror().</li> |
| </ul> |
| |
| |
| <h3><a name="http_core" id="http_core">http_core (changed)</a></h3> |
| |
| <ul> |
| <li>REMOVED ap_default_type, ap_requires, all 2.2 authnz API</li> |
| <li>Introduces Optional Functions for logio and authnz</li> |
| <li>New function ap_get_server_name_for_url to support ipv6 literals.</li> |
| <li>New function ap_register_errorlog_handler to register errorlog |
| format string handlers.</li> |
| <li>New function ap_state_query to determine if the server is in the |
| initial configuration preflight phase or not. This is both easier to |
| use and more correct than the old method of creating a pool userdata |
| entry in the process pool.</li> |
| <li>New function ap_get_conn_socket to get the socket descriptor for a |
| connection. This should be used instead of accessing the core |
| connection config directly.</li> |
| </ul> |
| |
| |
| <h3><a name="httpd" id="httpd">httpd (changed)</a></h3> |
| |
| <ul> |
| <li>Introduce per-directory, per-module loglevel</li> |
| <li>New loglevels APLOG_TRACEn</li> |
| <li>Introduce errorlog ids for requests and connections</li> |
| <li>Support for mod_request kept_body</li> |
| <li>Support buffering filter data for async requests</li> |
| <li>New CONN_STATE values</li> |
| <li>Function changes: ap_escape_html updated; ap_unescape_all, |
| ap_escape_path_segment_buffer</li> |
| <li>Modules that load other modules later than the EXEC_ON_READ config |
| reading stage need to call ap_reserve_module_slots() or |
| ap_reserve_module_slots_directive() in their pre_config hook.</li> |
| </ul> |
| |
| |
| <h3><a name="http_log" id="http_log">http_log (changed)</a></h3> |
| |
| <ul> |
| <li>Introduce per-directory, per-module loglevel</li> |
| <li>New loglevels APLOG_TRACEn</li> |
| <li>ap_log_*error become macro wrappers (fully back-compatible if |
| APLOG_MARK macro is used)</li> |
| <li>piped logging revamped</li> |
| <li>module_index added to error_log hook</li> |
| <li>new function: ap_log_command_line</li> |
| </ul> |
| |
| |
| <h3><a name="http_request" id="http_request">http_request (changed)</a></h3> |
| |
| <ul> |
| <li>New auth_internal API and auth_provider API</li> |
| <li>New EOR bucket type</li> |
| <li>New function ap_process_async_request</li> |
| <li>New flags AP_AUTH_INTERNAL_PER_CONF and AP_AUTH_INTERNAL_PER_URI</li> |
| <li>New access_checker_ex hook to apply additional access control and/or |
| bypass authentication.</li> |
| <li>New functions ap_hook_check_access_ex, ap_hook_check_access, |
| ap_hook_check_authn, ap_hook_check_authz which accept |
| AP_AUTH_INTERNAL_PER_* flags</li> |
| <li>DEPRECATED direct use of ap_hook_access_checker, access_checker_ex, |
| ap_hook_check_user_id, ap_hook_auth_checker</li> |
| </ul> |
| <p>When possible, registering all access control hooks (including |
| authentication and authorization hooks) using AP_AUTH_INTERNAL_PER_CONF |
| is recommended. If all modules' access control hooks are registered |
| with this flag, then whenever the server handles an internal |
| sub-request that matches the same set of access control configuration |
| directives as the initial request (which is the common case), it can |
| avoid invoking the access control hooks another time.</p> |
| <p>If your module requires the old behavior and must perform access |
| control checks on every sub-request with a different URI from the |
| initial request, even if that URI matches the same set of access |
| control configuration directives, then use AP_AUTH_INTERNAL_PER_URI.</p> |
| |
| |
| <h3><a name="mod_auth" id="mod_auth">mod_auth (NEW!)</a></h3> |
| |
| <p>Introduces the new provider framework for authn and authz</p> |
| |
| |
| <h3><a name="mod_cache" id="mod_cache">mod_cache (changed)</a></h3> |
| |
| <p>Introduces a commit_entity() function to the cache provider interface, |
| allowing atomic writes to cache. Add a cache_status() hook to report |
| the cache decision. Remove all private structures and functions from the |
| public mod_cache.h header file.</p> |
| |
| |
| <h3><a name="mod_core" id="mod_core">mod_core (NEW!)</a></h3> |
| |
| <p>This introduces low-level APIs to send arbitrary headers, |
| and exposes functions to handle HTTP OPTIONS and TRACE.</p> |
| |
| |
| <h3><a name="mod_cache_disk" id="mod_cache_disk">mod_cache_disk (changed)</a></h3> |
| |
| <p>Changes the disk format of the disk cache to support atomic cache |
| updates without locking. The device/inode pair of the body file is |
| embedded in the header file, allowing confirmation that the header |
| and body belong to one another.</p> |
| |
| |
| <h3><a name="mod_disk_cache" id="mod_disk_cache">mod_disk_cache (renamed)</a></h3> |
| |
| <p>The mod_disk_cache module has been renamed to mod_cache_disk in |
| order to be consistent with the naming of other modules within the |
| server.</p> |
| |
| |
| <h3><a name="mod_request" id="mod_request">mod_request (NEW!)</a></h3> |
| |
| <p>The API for <code class="module"><a href="../mod/mod_request.html">mod_request</a></code>, to make input data |
| available to multiple application/handler modules where required, |
| and to parse HTML form data.</p> |
| |
| |
| <h3><a name="mpm_common" id="mpm_common">mpm_common (changed)</a></h3> |
| |
| <ul> |
| <li>REMOVES: accept, lockfile, lock_mech, set_scoreboard (locking uses the new ap_mutex API)</li> |
| <li>NEW API to drop privileges (delegates this platform-dependent |
| function to modules)</li> |
| <li>NEW Hooks: mpm_query, timed_callback, and get_name</li> |
| <li>CHANGED interfaces: monitor hook, |
| ap_reclaim_child_processes, ap_relieve_child_processes</li> |
| </ul> |
| |
| |
| <h3><a name="scoreboard" id="scoreboard">scoreboard (changed)</a></h3> |
| |
| <p>ap_get_scoreboard_worker is gratuitously made non-back-compatible |
| as an alternative version is introduced. Additional proxy_balancer |
| support. Child status stuff revamped.</p> |
| |
| |
| <h3><a name="util_cookies" id="util_cookies">util_cookies (NEW!)</a></h3> |
| |
| <p>Introduces a new API for managing HTTP Cookies.</p> |
| |
| |
| <h3><a name="util_ldap" id="util_ldap">util_ldap (changed)</a></h3> |
| |
| <p>I have yet to get a handle on this update.</p> |
| |
| |
| <h3><a name="util_mutex" id="util_mutex">util_mutex (NEW!)</a></h3> |
| |
| <p>A wrapper for APR proc and global mutexes in httpd.</p> |
| |
| |
| <h3><a name="util_script" id="util_script">util_script (changed)</a></h3> |
| |
| <p>NEW: ap_args_to_table</p> |
| |
| |
| <h3><a name="util_time" id="util_time">util_time (changed)</a></h3> |
| |
| <p>NEW: ap_recent_ctime_ex</p> |
| |
| |
| </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> |
| <div class="section"> |
| <h2><a name="upgrading" id="upgrading">Specific information on upgrading modules from 2.2</a></h2> |
| |
| |
| <h3><a name="upgrading_logging" id="upgrading_logging">Logging</a></h3> |
| |
| <p>In order to take advantage of per-module loglevel configuration, any |
| source file that calls the <code>ap_log_*</code> functions should declare |
| which module it belongs to. If the module's module_struct is called |
| <code>foo_module</code>, the following code can be used to remain |
| backward compatible with HTTPD 2.0 and 2.2:</p> |
| <div class="example"><p><code> |
| #include <http_log.h><br /> |
| <br /> |
| #ifdef APLOG_USE_MODULE<br /> |
| APLOG_USE_MODULE(foo);<br /> |
| #endif |
| </code></p></div> |
| <p>Note: This is absolutely required for C++-language modules. It |
| can be skipped for C-language modules, though that breaks |
| module-specific log level support for files without it.</p> |
| <p>The number of parameters of the <code>ap_log_*</code> functions and the |
| definition of <code>APLOG_MARK</code> has changed. Normally, the change |
| is completely transparent. However, changes are required if a |
| module uses <code>APLOG_MARK</code> as a parameter to its own functions |
| or if a module calls <code>ap_log_*</code> without passing |
| <code>APLOG_MARK</code>. A module which uses wrappers |
| around <code>ap_log_*</code> typically uses both of these constructs.</p> |
| |
| <p>The easiest way to change code which passes <code>APLOG_MARK</code> to |
| its own functions is to define and use a different macro that expands to |
| the parameters required by those functions, as <code>APLOG_MARK</code> |
| should only be used when calling <code>ap_log_*</code> |
| directly. In this way, the code will remain compatible with HTTPD 2.0 |
| and 2.2.</p> |
| |
| <p>Code which calls <code>ap_log_*</code> without passing |
| <code>APLOG_MARK</code> will necessarily differ between 2.4 and earlier |
| releases, as 2.4 requires a new third argument, |
| <code>APLOG_MODULE_INDEX</code>.</p> |
| |
| <div class="example"><p><code> |
| /* code for httpd 2.0/2.2 */<br /> |
| ap_log_perror(file, line, APLOG_ERR, 0, p, "Failed to allocate dynamic lock structure");<br /> |
| <br /> |
| /* code for httpd 2.4 */<br /> |
| ap_log_perror(file, line, APLOG_MODULE_INDEX, APLOG_ERR, 0, p, "Failed to allocate dynamic lock structure");<br /> |
| <br /> |
| </code></p></div> |
| |
| <p>A <code>server_rec</code> pointer must be passed to |
| <code>ap_log_error()</code> when called after startup. This |
| was always appropriate, but there are even more limitations with |
| a <code>NULL</code> <code>server_rec</code> in 2.4 than in |
| previous releases. Beginning with 2.3.12, the global variable |
| <code>ap_server_conf</code> can always be used as |
| the <code>server_rec</code> parameter, as it will be |
| <code>NULL</code> only when it is valid to pass <code>NULL</code> |
| to <code>ap_log_error()</code>. <code>ap_server_conf</code> |
| should be used only when a more appropriate <code>server_rec</code> |
| is not available.</p> |
| |
| <p>Consider the following changes to take advantage of the new |
| <code>APLOG_TRACE1..8</code> log levels:</p> |
| <ul> |
| <li>Check current use of <code>APLOG_DEBUG</code> and |
| consider if one of the <code>APLOG_TRACEn</code> levels is |
| more appropriate.</li> |
| <li>If your module currently has a mechanism for configuring |
| the amount of debug logging which is performed, consider |
| eliminating that mechanism and relying on the use of |
| different <code>APLOG_TRACEn</code> levels. If expensive |
| trace processing needs to be bypassed depending on the |
| configured log level, use the <code>APLOGtrace<em>n</em></code> |
| and <code>APLOGrtrace<em>n</em></code> macros to first check |
| if tracing is enabled.</li> |
| </ul> |
| |
| <p>Modules sometimes add process id and/or thread id to their log |
| messages. These ids are now logged by default, so it may not |
| be necessary for the module to log them explicitly. (Users may |
| remove them from the error log format, but they can be |
| instructed to add it back if necessary for problem diagnosis.)</p> |
| |
| |
| <h3><a name="upgrading_byfunction" id="upgrading_byfunction">If your module uses these existing APIs...</a></h3> |
| |
| |
| <dl> |
| <dt><code>ap_default_type()</code></dt> |
| <dd>This is no longer available; Content-Type must be configured |
| explicitly or added by the application.</dd> |
| |
| <dt><code>ap_get_server_name()</code></dt> |
| <dd>If the returned server name is used in a URL, |
| use <code>ap_get_server_name_for_url()</code> instead. This new |
| function handles the odd case where the server name is an IPv6 |
| literal address.</dd> |
| |
| <dt><code>ap_get_server_version()</code></dt> |
| <dd>For logging purposes, where detailed information is |
| appropriate, use <code>ap_get_server_description()</code>. |
| When generating output, where the amount of information |
| should be configurable by ServerTokens, use |
| <code>ap_get_server_banner()</code>.</dd> |
| |
| <dt><code>ap_graceful_stop_signalled()</code></dt> |
| <dd>Replace with a call |
| to <code>ap_mpm_query(AP_MPMQ_MPM_STATE)</code> and checking for |
| state <code>AP_MPMQ_STOPPING</code>.</dd> |
| |
| <dt><code>ap_max_daemons_limit</code>, <code>ap_my_generation</code>, |
| and <code>ap_threads_per_child</code></dt> |
| <dd>Use <code>ap_mpm_query()</code> query codes |
| <code>AP_MPMQ_MAX_DAEMON_USED</code>, <code>AP_MPMQ_GENERATION</code>, |
| and <code>AP_MPMQ_MAX_THREADS</code>, respectively.</dd> |
| |
| <dt><code>ap_mpm_query()</code></dt> |
| <dd>Ensure that it is not used until after the register-hooks |
| hook has completed. Otherwise, an MPM built as a DSO |
| would not have had a chance to enable support for this |
| function.</dd> |
| |
| <dt><code>ap_server_conf->process->pool</code> |
| userdata</dt> |
| <dd> |
| Optional: |
| <ul> |
| <li>If your module uses this to determine which pass of the |
| startup hooks is being run, |
| use <code>ap_state_query(AP_SQ_MAIN_STATE)</code>.</li> |
| <li>If your module uses this to maintain data across the |
| unloading and reloading of your module, use |
| <code>ap_retained_data_create()</code> and |
| <code>ap_retained_data_get()</code>.</li> |
| </ul> |
| </dd> |
| |
| <dt><code>apr_global_mutex_create()</code>, |
| <code>apr_proc_mutex_create()</code></dt> |
| <dd>Optional: See <code>ap_mutex_register()</code>, |
| <code>ap_global_mutex_create()</code>, and |
| <code>ap_proc_mutex_create()</code>; these allow your |
| mutexes to be configurable with |
| the <code class="directive"><a href="../mod/core.html#mutex">Mutex</a></code> directive; |
| you can also remove any configuration mechanisms in your |
| module for such mutexes |
| </dd> |
| |
| <dt><code>CORE_PRIVATE</code></dt> |
| <dd>This is now unnecessary and ignored.</dd> |
| |
| <dt><code>dav_new_error()</code> |
| and <code>dav_new_error_tag()</code></dt> |
| <dd>Previously, these assumed that <code>errno</code> contained |
| information describing the failure. Now, |
| an <code>apr_status_t</code> parameter must be provided. Pass |
| 0/APR_SUCCESS if there is no such error information, or a valid |
| <code>apr_status_t</code> value otherwise.</dd> |
| |
| <dt><code>mpm_default.h</code>, <code>DEFAULT_LOCKFILE</code>, |
| <code>DEFAULT_THREAD_LIMIT</code>, <code>DEFAULT_PIDLOG</code>, |
| etc.</dt> |
| <dd>The header file and most of the default configuration |
| values set in it are no longer visible to modules. (Most can |
| still be overridden at build time.) <code>DEFAULT_PIDLOG</code> |
| and <code>DEFAULT_REL_RUNTIMEDIR</code> are now universally |
| available via <code>ap_config.h</code>.</dd> |
| |
| <dt><code>unixd_config</code></dt> |
| <dd>This has been renamed to ap_unixd_config.</dd> |
| </dl> |
| |
| |
| <h3><a name="upgrading_byfeature" id="upgrading_byfeature">If your module interfaces with this feature...</a></h3> |
| |
| <dl> |
| <dt>suEXEC</dt> |
| <dd>Optional: If your module logs an error |
| when <code>ap_unixd_config.suexec_enabled</code> is 0, |
| also log the value of the new |
| field <code>suexec_disabled_reason</code>, which contains an |
| explanation of why it is not available.</dd> |
| |
| <dt>Extended status data in the scoreboard</dt> |
| <dd>In previous releases, <code>ExtendedStatus</code> had to be |
| set to <code>On</code>, which in turn required that |
| mod_status was loaded. In 2.4, just |
| set <code>ap_extended_status</code> to <code>1</code> in a |
| pre-config hook and the extended status data will be |
| available.</dd> |
| |
| </dl> |
| |
| |
| <h3><a name="upgrading_newfeatures" id="upgrading_newfeatures">Does your module...</a></h3> |
| |
| <dl> |
| <dt>Parse query args</dt> |
| <dd>Consider if <code>ap_args_to_table()</code> would be |
| helpful.</dd> |
| |
| <dt>Parse form data...</dt> |
| <dd>Use <code>ap_parse_form_data()</code>.</dd> |
| |
| <dt>Check for request header fields <code>Content-Length</code> |
| and <code>Transfer-Encoding</code> to see if a body was |
| specified</dt> |
| <dd>Use <code>ap_request_has_body()</code>.</dd> |
| |
| <dt>Implement cleanups which clear pointer variables</dt> |
| <dd>Use <code>ap_pool_cleanup_set_null()</code>.</dd> |
| </dl> |
| |
| |
| </div></div> |
| <div class="bottomlang"> |
| <p><span>Available Languages: </span><a href="../en/developer/new_api_2_4.html" title="English"> en </a></p> |
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