<P>The HTTP server that comes with <strong>lwIP</strong> has been extended to support rudimentary <strong>Server Side Include (SSI)</strong> facility. To enable the SSI support in the lwIP-HTTP server, you need to define the macro <CODE>INCLUDE_HTTPD_SSI</CODE> in the <CODE>lwipopts.h</CODE> header file.
You must also provide your SSI callback function and register it by calling the <CODE>http_set_ssi_handler()</CODE> function. The HTTP server will then scan each file with extension <CODE>.shtml</CODE>, <CODE>.shtm</CODE> or <CODE>.ssi</CODE> for the SSI tags of the form <CODE><!--#tag--></CODE> and will replace on-the-fly every recognized SSI tag with the string composed by your SSI callback function. See the HTML source code for this web page (<CODE>ssi_demo.shtm</CODE>) and the SSI callback function definition in <CODE>lwipmgr.c</CODE>.
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<P>While designing your own SSI tags, remember that the tag names are limited to 8 characters and the length of the replacement strings cannot exceed 192 characters. You can re-define these limits by changing the macros <CODE>MAX_TAG_NAME_LEN</CODE> and <CODE>MAX_TAG_INSERT_LEN</CODE>, respectively, in the <CODE>http.h</CODE> header file.
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<P>Please refer to the Quantum Leaps Application Note: <A HREF="http://www.state-machine.com/lwip/AN_QP_and_lwIP.pdf" TARGET="_blank">"QP and lwIP TCP/IP Stack"</A> for more information. The Application Note is included in the QP-lwIP example code download.
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<A NAME="Example"></A>
<H1>SSI Example</H1>
<P>The following table contains SSI tags embedded in the HTML of this web page. Client browsers never see these tags, as the lwIP-HTTP server replaces them on-the-fly while serving this page. These particular SSI tags cause the target to generate various <strong>lwIP</strong> link statistics. Please click the Refresh button on your browser to cause re-loading of this page and updating the statistics:
<P><strong>NOTE:</strong> the webpage loads much slower than the others, because it contains 12 SSI tags, and each tag is sent is a separate TCP/IP packet.
