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