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391a2c66b8
Corrected default values. Corrected the ISPAIFileChache/ISAPIFileCache directive. The correct name is ISAPICacheFile. Added description for the ISAPIFakeAsync directive. git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96535 13f79535-47bb-0310-9956-ffa450edef68
304 lines
11 KiB
XML
304 lines
11 KiB
XML
<?xml version="1.0"?>
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<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
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<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
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<modulesynopsis>
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<name>mod_isapi</name>
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<description>ISAPI Extensions within Apache for Windows</description>
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<status>Base</status>
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<sourcefile>mod_isapi.c</sourcefile>
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<identifier>isapi_module</identifier>
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<compatibility>Win32 only</compatibility>
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<summary>
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<p>This module implements the Internet Server extension API. It
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allows Internet Server extensions (<em>e.g.</em> ISAPI .dll
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modules) to be served by Apache for Windows, subject to the
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noted restrictions.</p>
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<p>ISAPI extension modules (.dll files) are written by third
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parties. The Apache Group does not author these modules, so we
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provide no support for them. Please contact the ISAPI's author
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directly if you are experiencing problems running their ISAPI
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extention. <strong>Please <em>do not</em> post such problems to
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Apache's lists or bug reporting pages.</strong></p>
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</summary>
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<section><title>Usage</title> <p>In the server configuration file, use
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the <directive module="mod_mime">AddHandler</directive> directive to
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associate ISAPI files with the <code>isapi-isa</code> handler, and map
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it to the with their file extensions. To enable any .dll file to be
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processed as an ISAPI extention, edit the httpd.conf file and add the
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following line:</p>
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<example>
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AddHandler isapi-isa .dll
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</example>
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<p>There is no capability within the Apache server to leave a
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requested module loaded. However, you may preload and keep a
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specific module loaded by using the following syntax in your
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httpd.conf:</p>
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<example>
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ISAPICacheFile c:/WebWork/Scripts/ISAPI/mytest.dll
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</example>
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<p>Whether or not you have preloaded an ISAPI extension, all
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ISAPI extensions are governed by the same permissions and
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restrictions as CGI scripts. That is, <code>Options
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ExecCGI</code> must be set for the directory that contains the
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ISAPI .dll file.</p>
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<p>Review the <a href="#notes">Additional Notes</a> and the <a
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href="#journal">Programmer's Journal</a> for additional details
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and clarification of the specific ISAPI support offered by
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mod_isapi.</p>
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</section>
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<section id="notes"><title>Additional Notes</title>
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<p>Apache's ISAPI implementation conforms to all of the ISAPI
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2.0 specification, except for some "Microsoft-specific"
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extensions dealing with asynchronous I/O. Apache's I/O model
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does not allow asynchronous reading and writing in a manner
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that the ISAPI could access. If an ISA tries to access
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unsupported features, including async I/O, a message is placed
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in the error log to help with debugging. Since these messages
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can become a flood, the directive <code>ISAPILogNotSupported
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Off</code> exists to quiet this noise.</p>
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<p>Some servers, like Microsoft IIS, load the ISAPI extension
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into the server and keep it loaded until memory usage is too
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high, or unless configuration options are specified. Apache
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currently loads and unloads the ISAPI extension each time it is
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requested, unless the ISAPICacheFile directive is specified.
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This is inefficient, but Apache's memory model makes this the
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most effective method. Many ISAPI modules are subtly
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incompatible with the Apache server, and unloading these
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modules helps to ensure the stability of the server.</p>
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<p>Also, remember that while Apache supports ISAPI Extensions,
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it <strong>does not support ISAPI Filters.</strong> Support for
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filters may be added at a later date, but no support is planned
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at this time.</p>
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</section>
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<section id="journal"><title>Programmer's Journal</title>
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<p>If you are programming Apache 2.0 <module>mod_isapi</module>
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modules, you must limit your calls to ServerSupportFunction to the
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following directives:</p>
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<dl>
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<dt>HSE_REQ_SEND_URL_REDIRECT_RESP</dt>
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<dd>Redirect the user to another location.<br />
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This must be a fully qualified URL (e.g.
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http://server/location).</dd>
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<dt>HSE_REQ_SEND_URL</dt>
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<dd>Redirect the user to another location.<br />
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This cannot be a fully qualified URL, you are not allowed to
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pass the protocol or a server name (e.g. simply
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/location).<br />
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This redirection is handled by the server, not the
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browser.<br />
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<strong>Warning:</strong> in their recent documentation,
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Microsoft appears to have abandoned the distinction between
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the two HSE_REQ_SEND_URL functions. Apache continues to treat
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them as two distinct functions with different requirements
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and behaviors.</dd>
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<dt>HSE_REQ_SEND_RESPONSE_HEADER</dt>
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<dd>Apache accepts a response body following the header if it
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follows the blank line (two consecutive newlines) in the
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headers string argument. This body cannot contain NULLs,
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since the headers argument is NULL terminated.</dd>
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<dt>HSE_REQ_DONE_WITH_SESSION</dt>
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<dd>Apache considers this a no-op, since the session will be
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finished when the ISAPI returns from processing.</dd>
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<dt>HSE_REQ_MAP_URL_TO_PATH</dt>
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<dd>Apache will translate a virtual name to a physical
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name.</dd>
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<dt>HSE_APPEND_LOG_PARAMETER</dt>
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<dd>
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This logged message may be captured in any of the following
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logs:
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<ul>
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<li>in the \"%{isapi-parameter}n\" component in a
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CustomLog directive</li>
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<li>in the %q log component with the
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ISAPIAppendLogToQuery On directive</li>
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<li>in the error log with the ISAPIAppendLogToErrors On
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directive</li>
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</ul>
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The first option, the %{isapi-parameter}n component, is
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always available and prefered.
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</dd>
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<dt>HSE_REQ_IS_KEEP_CONN</dt>
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<dd>Will return the negotiated Keep-Alive status.</dd>
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<dt>HSE_REQ_SEND_RESPONSE_HEADER_EX</dt>
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<dd>Will behave as documented, although the fKeepConn flag is
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ignored.</dd>
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<dt>HSE_REQ_IS_CONNECTED</dt>
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<dd>Will report false if the request has been aborted.</dd>
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</dl>
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<p>Apache returns FALSE to any unsupported call to
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ServerSupportFunction, and sets the GetLastError value to
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ERROR_INVALID_PARAMETER.</p>
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<p>ReadClient retrieves the request body exceeding the initial
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buffer (defined by ISAPIReadAheadBuffer). Based on the
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ISAPIReadAheadBuffer setting (number of bytes to buffer prior
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to calling the ISAPI handler) shorter requests are sent
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complete to the extension when it is invoked. If the request is
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longer, the ISAPI extension must use ReadClient to retrieve the
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remaining request body.</p>
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<p>WriteClient is supported, but only with the HSE_IO_SYNC flag
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or no option flag (value of 0). Any other WriteClient request
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will be rejected with a return value of FALSE, and a
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GetLastError value of ERROR_INVALID_PARAMETER.</p>
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<p>GetServerVariable is supported, although extended server
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variables do not exist (as defined by other servers.) All the
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usual Apache CGI environment variables are available from
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GetServerVariable, as well as the ALL_HTTP and ALL_RAW
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values.</p>
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<p>Apache 2.0 <module>mod_isapi</module> supports additional
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features introduced in later versions of the ISAPI specification,
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as well as limited emulation of async I/O and the TransmitFile
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semantics. Apache also supports preloading ISAPI .dlls for
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performance, neither of which were not available under Apache 1.3
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mod_isapi.</p>
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</section>
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<directivesynopsis>
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<name>ISAPICacheFile</name>
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<description>ISAPI .dll files to be loaded at startup</description>
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<syntax>ISAPICacheFile <em>file-path</em> [<em>file-path</em>] ...</syntax>
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<contextlist><context>server config</context>
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<context>virtual host</context></contextlist>
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<usage>
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<p>Specifies a space-separated list of file names to be loaded
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when the Apache server is launched, and remain loaded until the
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server is shut down. This directive may be repeated for every
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ISAPI .dll file desired. The full path name of each file should
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be specified.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>ISAPIReadAheadBuffer</name>
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<description>Size of the Read Ahead Buffer sent to ISAPI
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extensions</description>
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<syntax>ISAPIReadAheadBuffer <em>size</em></syntax>
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<default>ISAPIReadAheadBuffer 49152</default>
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<contextlist><context>server config</context>
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<context>directory</context>
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<context>.htaccess</context></contextlist>
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<override>FileInfo</override>
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<usage>
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<p>Defines the maximum size of the Read Ahead Buffer sent to
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ISAPI extensions when they are initially invoked. All remaining
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data must be retrieved using the ReadClient callback; some
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ISAPI extensions may not support the ReadClient function. Refer
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questions to the ISAPI extension's author.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>ISAPILogNotSupported</name>
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<description>Log unsupported feature requests from ISAPI
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extensions</description>
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<syntax>ISAPILogNotSupported on|off</syntax>
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<default>ISAPILogNotSupported off</default>
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<contextlist><context>server config</context>
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<context>virtual host</context>
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<context>directory</context>
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<context>.htaccess</context></contextlist>
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<override>FileInfo</override>
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<usage>
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<p>Logs all requests for unsupported features from ISAPI
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extensions in the server error log. This may help administrators
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to track down problems. Once set to on and all desired ISAPI modules
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are functioning, it should be set back to off.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>ISAPIAppendLogToErrors</name>
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<description>Record HSE_APPEND_LOG_PARAMETER requests from ISAPI
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extensions to the error log</description>
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<syntax>ISAPIAppendLogToErrors on|off</syntax>
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<default>ISAPIAppendLogToErrors off</default>
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<contextlist><context>server config</context>
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<context>virtual host</context>
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<context>directory</context>
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<context>.htaccess</context></contextlist>
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<override>FileInfo</override>
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<usage>
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<p>Record HSE_APPEND_LOG_PARAMETER requests from ISAPI
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extensions to the server error log.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>ISAPIAppendLogToQuery</name>
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<description>Record HSE_APPEND_LOG_PARAMETER requests from ISAPI
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extensions to the query field</description>
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<syntax>ISAPIAppendLogToQuery on|off</syntax>
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<default>ISAPIAppendLogToQuery on</default>
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<contextlist><context>server config</context>
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<context>virtual host</context>
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<context>directory</context>
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<context>.htaccess</context></contextlist>
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<override>FileInfo</override>
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<usage>
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<p>Record HSE_APPEND_LOG_PARAMETER requests from ISAPI
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extensions to the query field (appended to the CustomLog %q
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component).</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>ISAPIFakeAsync</name>
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<description>Fake asynchronous support for isapi callbacks</description>
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<syntax>ISAPIFakeAsync on|off</syntax>
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<default>ISAPIFakeAsync off</default>
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<contextlist><context>server config</context>
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<context>virtual host</context>
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<context>directory</context>
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<context>.htaccess</context></contextlist>
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<override>FileInfo</override>
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<usage>
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<p>While set to on, asynchronous support for isapi callbacks is
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simulated.</p>
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</usage>
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</directivesynopsis>
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</modulesynopsis> |