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16 <p class="apache">Apache HTTP Server Version 2.1</p>
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20 <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> > <a href="./">Modules</a></div>
21 <div id="page-content">
22 <div id="preamble"><h1>Apache Module mod_isapi</h1>
24 <p><span>Available Languages: </span><a href="../en/mod/mod_isapi.html" title="English"> en </a> |
25 <a href="../ko/mod/mod_isapi.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
27 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>ISAPI Extensions within Apache for Windows</td></tr>
28 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Base</td></tr>
29 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>isapi_module</td></tr>
30 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_isapi.c</td></tr>
31 <tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only</td></tr></table>
34 <p>This module implements the Internet Server extension API. It
35 allows Internet Server extensions (<em>e.g.</em> ISAPI .dll
36 modules) to be served by Apache for Windows, subject to the
37 noted restrictions.</p>
39 <p>ISAPI extension modules (.dll files) are written by third
40 parties. The Apache Group does not author these modules, so we
41 provide no support for them. Please contact the ISAPI's author
42 directly if you are experiencing problems running their ISAPI
43 extension. <strong>Please <em>do not</em> post such problems to
44 Apache's lists or bug reporting pages.</strong></p>
46 <div id="quickview"><h3 class="directives">Directives</h3>
48 <li><img alt="" src="../images/down.gif" /> <a href="#isapiappendlogtoerrors">ISAPIAppendLogToErrors</a></li>
49 <li><img alt="" src="../images/down.gif" /> <a href="#isapiappendlogtoquery">ISAPIAppendLogToQuery</a></li>
50 <li><img alt="" src="../images/down.gif" /> <a href="#isapicachefile">ISAPICacheFile</a></li>
51 <li><img alt="" src="../images/down.gif" /> <a href="#isapifakeasync">ISAPIFakeAsync</a></li>
52 <li><img alt="" src="../images/down.gif" /> <a href="#isapilognotsupported">ISAPILogNotSupported</a></li>
53 <li><img alt="" src="../images/down.gif" /> <a href="#isapireadaheadbuffer">ISAPIReadAheadBuffer</a></li>
57 <li><img alt="" src="../images/down.gif" /> <a href="#usage">Usage</a></li>
58 <li><img alt="" src="../images/down.gif" /> <a href="#notes">Additional Notes</a></li>
59 <li><img alt="" src="../images/down.gif" /> <a href="#journal">Programmer's Journal</a></li>
61 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
63 <h2><a name="usage" id="usage">Usage</a></h2>
65 <p>In the server configuration file, use
66 the <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> directive to
67 associate ISAPI files with the <code>isapi-isa</code> handler, and map
68 it to them with their file extensions. To enable any .dll file to be
69 processed as an ISAPI extension, edit the httpd.conf file and add the
71 <div class="example"><p><code>
72 AddHandler isapi-isa .dll
75 <p>There is no capability within the Apache server to leave a
76 requested module loaded. However, you may preload and keep a
77 specific module loaded by using the following syntax in your
79 <div class="example"><p><code>
80 ISAPICacheFile c:/WebWork/Scripts/ISAPI/mytest.dll
83 <p>Whether or not you have preloaded an ISAPI extension, all
84 ISAPI extensions are governed by the same permissions and
85 restrictions as CGI scripts. That is, <code class="directive"><a href="../mod/core.html#options">Options</a></code> <code>ExecCGI</code> must be set for the
86 directory that contains the ISAPI .dll file.</p>
88 <p>Review the <a href="#notes">Additional Notes</a> and the <a href="#journal">Programmer's Journal</a> for additional details
89 and clarification of the specific ISAPI support offered by
90 <code class="module"><a href="../mod/mod_isapi.html">mod_isapi</a></code>.</p>
91 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
93 <h2><a name="notes" id="notes">Additional Notes</a></h2>
95 <p>Apache's ISAPI implementation conforms to all of the ISAPI
96 2.0 specification, except for some "Microsoft-specific"
97 extensions dealing with asynchronous I/O. Apache's I/O model
98 does not allow asynchronous reading and writing in a manner
99 that the ISAPI could access. If an ISA tries to access
100 unsupported features, including async I/O, a message is placed
101 in the error log to help with debugging. Since these messages
102 can become a flood, the directive <code>ISAPILogNotSupported
103 Off</code> exists to quiet this noise.</p>
105 <p>Some servers, like Microsoft IIS, load the ISAPI extension
106 into the server and keep it loaded until memory usage is too
107 high, or unless configuration options are specified. Apache
108 currently loads and unloads the ISAPI extension each time it is
109 requested, unless the <code class="directive"><a href="#isapicachefile">ISAPICacheFile</a></code> directive is specified.
110 This is inefficient, but Apache's memory model makes this the
111 most effective method. Many ISAPI modules are subtly
112 incompatible with the Apache server, and unloading these
113 modules helps to ensure the stability of the server.</p>
115 <p>Also, remember that while Apache supports ISAPI Extensions,
116 it <strong>does not support ISAPI Filters</strong>. Support for
117 filters may be added at a later date, but no support is planned
119 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
120 <div class="section">
121 <h2><a name="journal" id="journal">Programmer's Journal</a></h2>
123 <p>If you are programming Apache 2.0 <code class="module"><a href="../mod/mod_isapi.html">mod_isapi</a></code>
124 modules, you must limit your calls to <code>ServerSupportFunction</code>
125 to the following directives:</p>
128 <dt><code>HSE_REQ_SEND_URL_REDIRECT_RESP</code></dt>
129 <dd>Redirect the user to another location.<br />
130 This must be a fully qualified URL (<em>e.g.</em>
131 <code>http://server/location</code>).</dd>
133 <dt><code>HSE_REQ_SEND_URL</code></dt>
134 <dd>Redirect the user to another location.<br />
135 This cannot be a fully qualified URL, you are not allowed to
136 pass the protocol or a server name (<em>e.g.</em> simply
137 <code>/location</code>).<br />
138 This redirection is handled by the server, not the
140 <div class="warning"><h3>Warning</h3>
141 <p>In their recent documentation, Microsoft appears to have
142 abandoned the distinction between the two
143 <code>HSE_REQ_SEND_URL</code> functions. Apache continues to treat
144 them as two distinct functions with different requirements
148 <dt><code>HSE_REQ_SEND_RESPONSE_HEADER</code></dt>
149 <dd>Apache accepts a response body following the header if it
150 follows the blank line (two consecutive newlines) in the
151 headers string argument. This body cannot contain NULLs,
152 since the headers argument is NULL terminated.</dd>
154 <dt><code>HSE_REQ_DONE_WITH_SESSION</code></dt>
155 <dd>Apache considers this a no-op, since the session will be
156 finished when the ISAPI returns from processing.</dd>
158 <dt><code>HSE_REQ_MAP_URL_TO_PATH</code></dt>
159 <dd>Apache will translate a virtual name to a physical
162 <dt><code>HSE_APPEND_LOG_PARAMETER</code></dt>
164 This logged message may be captured in any of the following
168 <li>in the <code>\"%{isapi-parameter}n\"</code> component in a
169 <code class="directive"><a href="../mod/mod_log_config.html#customlog">CustomLog</a></code>
172 <li>in the <code>%q</code> log component with the
173 <code class="directive"><a href="#isapiappendlogtoquery">ISAPIAppendLogToQuery</a></code>
174 <code>On</code> directive</li>
176 <li>in the error log with the <code class="directive"><a href="#isapiappendlogtoerrors">ISAPIAppendLogToErrors</a></code> <code>On</code> directive</li>
179 <p>The first option, the <code>%{isapi-parameter}n</code> component,
180 is always available and preferred.</p>
183 <dt><code>HSE_REQ_IS_KEEP_CONN</code></dt>
184 <dd>Will return the negotiated Keep-Alive status.</dd>
186 <dt><code>HSE_REQ_SEND_RESPONSE_HEADER_EX</code></dt>
187 <dd>Will behave as documented, although the <code>fKeepConn</code>
188 flag is ignored.</dd>
190 <dt><code>HSE_REQ_IS_CONNECTED</code></dt>
191 <dd>Will report false if the request has been aborted.</dd>
194 <p>Apache returns <code>FALSE</code> to any unsupported call to
195 <code>ServerSupportFunction</code>, and sets the
196 <code>GetLastError</code> value to
197 <code>ERROR_INVALID_PARAMETER</code>.</p>
199 <p><code>ReadClient</code> retrieves the request body exceeding the
200 initial buffer (defined by <code class="directive"><a href="#isapireadaheadbuffer">ISAPIReadAheadBuffer</a></code>). Based on the
201 <code class="directive">ISAPIReadAheadBuffer</code> setting (number of bytes
202 to buffer prior to calling the ISAPI handler) shorter requests are sent
203 complete to the extension when it is invoked. If the request is
204 longer, the ISAPI extension must use <code>ReadClient</code> to
205 retrieve the remaining request body.</p>
207 <p><code>WriteClient</code> is supported, but only with the
208 <code>HSE_IO_SYNC</code> flag or no option flag (value of
209 <code>0</code>). Any other <code>WriteClient</code> request
210 will be rejected with a return value of <code>FALSE</code>, and a
211 <code>GetLastError</code> value of
212 <code>ERROR_INVALID_PARAMETER</code>.</p>
214 <p><code>GetServerVariable</code> is supported, although extended server
215 variables do not exist (as defined by other servers.) All the
216 usual Apache CGI environment variables are available from
217 <code>GetServerVariable</code>, as well as the <code>ALL_HTTP</code>
218 and <code>ALL_RAW</code> values.</p>
220 <p>Apache 2.0 <code class="module"><a href="../mod/mod_isapi.html">mod_isapi</a></code> supports additional
221 features introduced in later versions of the ISAPI specification,
222 as well as limited emulation of async I/O and the
223 <code>TransmitFile</code> semantics. Apache also supports preloading
224 ISAPI .dlls for performance, neither of which were not available under
225 Apache 1.3 <code>mod_isapi</code>.</p>
227 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
228 <div class="directive-section"><h2><a name="ISAPIAppendLogToErrors" id="ISAPIAppendLogToErrors">ISAPIAppendLogToErrors</a> <a name="isapiappendlogtoerrors" id="isapiappendlogtoerrors">Directive</a></h2>
229 <table class="directive">
230 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Record HSE_APPEND_LOG_PARAMETER requests from
231 ISAPI extensions to the error log</td></tr>
232 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ISAPIAppendLogToErrors on|off</code></td></tr>
233 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ISAPIAppendLogToErrors off</code></td></tr>
234 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
235 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
236 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
237 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_isapi</td></tr>
239 <p>Record <code>HSE_APPEND_LOG_PARAMETER</code> requests from ISAPI
240 extensions to the server error log.</p>
243 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
244 <div class="directive-section"><h2><a name="ISAPIAppendLogToQuery" id="ISAPIAppendLogToQuery">ISAPIAppendLogToQuery</a> <a name="isapiappendlogtoquery" id="isapiappendlogtoquery">Directive</a></h2>
245 <table class="directive">
246 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Record HSE_APPEND_LOG_PARAMETER requests from
247 ISAPI extensions to the query field</td></tr>
248 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ISAPIAppendLogToQuery on|off</code></td></tr>
249 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ISAPIAppendLogToQuery on</code></td></tr>
250 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
251 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
252 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
253 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_isapi</td></tr>
255 <p>Record <code>HSE_APPEND_LOG_PARAMETER</code> requests from ISAPI
256 extensions to the query field (appended to the <code class="directive"><a href="../mod/mod_log_config.html#customlog">CustomLog</a></code> <code>%q</code>
260 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
261 <div class="directive-section"><h2><a name="ISAPICacheFile" id="ISAPICacheFile">ISAPICacheFile</a> <a name="isapicachefile" id="isapicachefile">Directive</a></h2>
262 <table class="directive">
263 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>ISAPI .dll files to be loaded at startup</td></tr>
264 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ISAPICacheFile <var>file-path</var> [<var>file-path</var>]
266 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
267 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
268 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_isapi</td></tr>
270 <p>Specifies a space-separated list of file names to be loaded
271 when the Apache server is launched, and remain loaded until the
272 server is shut down. This directive may be repeated for every
273 ISAPI .dll file desired. The full path name of each file should
274 be specified. If the path name is not absolute, it will be treated
275 relative to <code class="directive"><a href="../mod/core.html#serverroot">ServerRoot</a></code>.</p>
278 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
279 <div class="directive-section"><h2><a name="ISAPIFakeAsync" id="ISAPIFakeAsync">ISAPIFakeAsync</a> <a name="isapifakeasync" id="isapifakeasync">Directive</a></h2>
280 <table class="directive">
281 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Fake asynchronous support for ISAPI callbacks</td></tr>
282 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ISAPIFakeAsync on|off</code></td></tr>
283 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ISAPIFakeAsync off</code></td></tr>
284 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
285 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
286 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
287 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_isapi</td></tr>
289 <p>While set to on, asynchronous support for ISAPI callbacks is
293 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
294 <div class="directive-section"><h2><a name="ISAPILogNotSupported" id="ISAPILogNotSupported">ISAPILogNotSupported</a> <a name="isapilognotsupported" id="isapilognotsupported">Directive</a></h2>
295 <table class="directive">
296 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Log unsupported feature requests from ISAPI
298 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ISAPILogNotSupported on|off</code></td></tr>
299 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ISAPILogNotSupported off</code></td></tr>
300 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
301 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
302 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
303 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_isapi</td></tr>
305 <p>Logs all requests for unsupported features from ISAPI
306 extensions in the server error log. This may help administrators
307 to track down problems. Once set to on and all desired ISAPI modules
308 are functioning, it should be set back to off.</p>
311 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
312 <div class="directive-section"><h2><a name="ISAPIReadAheadBuffer" id="ISAPIReadAheadBuffer">ISAPIReadAheadBuffer</a> <a name="isapireadaheadbuffer" id="isapireadaheadbuffer">Directive</a></h2>
313 <table class="directive">
314 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Size of the Read Ahead Buffer sent to ISAPI
316 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ISAPIReadAheadBuffer <var>size</var></code></td></tr>
317 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ISAPIReadAheadBuffer 49152</code></td></tr>
318 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
319 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
320 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
321 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_isapi</td></tr>
323 <p>Defines the maximum size of the Read Ahead Buffer sent to
324 ISAPI extensions when they are initially invoked. All remaining
325 data must be retrieved using the <code>ReadClient</code> callback; some
326 ISAPI extensions may not support the <code>ReadClient</code> function.
327 Refer questions to the ISAPI extension's author.</p>
331 <div class="bottomlang">
332 <p><span>Available Languages: </span><a href="../en/mod/mod_isapi.html" title="English"> en </a> |
333 <a href="../ko/mod/mod_isapi.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
334 </div><div id="footer">
335 <p class="apache">Copyright 1999-2004 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
336 <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></div>