eXtended SSIs

Extender SSIs add three additional pragmas to SSIs.

printenv

<!--#printenv -->

which just dumps out the envrionment. Note: Apache 1.2 or better.

HTTP_REFERER=http://localhost/jlk/apache/include_ssi.shtml
HTTP_CONNECTION=Keep-Alive 
HTTP_USER_AGENT=Mozilla/4.0 [en] (WinNT; I)
HTTP_PRAGMA=no-cache 
HTTP_HOST=localhost 
HTTP_ACCEPT=image/gif,image/x-xbitmap, image/jpeg, image/pjpeg, */* 
HTTP_ACCEPT_LANGUAGE=en
HTTP_ACCEPT_CHARSET=iso-8859-1,*,utf-8 SystemRoot=C:\WINNT
COMSPEC=C:\WINNT\system32\cmd.exe 
WINDIR=C:\WINNT
PATH=C:\Perl\bin;c:\mks\mksnt;c:\winnt\system32;
    c:\winnt;c:\Netscape\server\plugins\dynamo;
SERVER_SOFTWARE=Apache/1.3b3 
SERVER_NAME=jaunty 
SERVER_PORT=80
REMOTE_HOST=127.0.0.1 
REMOTE_ADDR=127.0.0.1
DOCUMENT_ROOT=c:/apache/htdocs 
SERVER_ADMIN=jkissel@sybase.com
SCRIPT_FILENAME=c:/apache/htdocs/jlk/apache/xssi.shtml 
REMOTE_PORT=3586
GATEWAY_INTERFACE=CGI/1.1 SERVER_PROTOCOL=HTTP/1.0
REQUEST_METHOD=GET 
QUERY_STRING= 
REQUEST_URI=/jlk/apache/xssi.shtml
SCRIPT_NAME=/jlk/apache/xssi.shtml 
DATE_LOCAL=Thursday, 16-Apr-1998 11:43:58
British Summer Time DATE_GMT=Thursday, 16-Apr-1998 10:43:58 GMT
LAST_MODIFIED=Thursday, 16-Apr-1998 11:43:56 British Summer Time
DOCUMENT_URI=/jlk/apache/xssi.shtml 
DOCUMENT_PATH_INFO=
DOCUMENT_NAME=xssi.shtml Title=eXtended SSI

which you may or may not find interesting. But more importantly, XSSIs include conditional html.

Let me repeat that.

XSSIs provide conditional html!

Yes, you can detect whether I'm using Netscape or IE4 and display a different page for each of them without writing cgi scripts, JavaScripts or Jscripts, JavaApplets or ActiveX controls.

Now a message from the author

Please Don't!

Anyone who slaps a "this page is best viewed with Browser X" label on a Web page appears to be yearning for the bad old days, before the Web, when you had very little chance of reading a document written on another computer, another word processor, or another network.
[Tim Berners-Lee in Technology Review, July 1996]

So much for you taking notice of my opinions. How do we do this conditional html?

Flow Control Elements

<!--#if expr="test_condition" -->
<!--#elif expr="test_condition" -->
<!--#else -->
<!--#endif -->

where test_condition is

string     true if string is not empty 
string1 = string2 
string1 != string2 
string1 < string2 
string1 >= string2 
string1 < string2 
string1 >= string2 
Compare string1 with string 2. 
If string2 has the form /string/ then it is compared 
as a regular expression. Regular expressions have the 
same syntax as those found in the Unix egrep command. 
( test_condition ) 
     true if test_condition is true 
! test_condition 
     true if test_condition is false 
test_condition1 && test_condition2 
     true if both test_condition1 and test_condition2 are true 
test_condition1 || test_condition2 
     true if either test_condition1 or test_condition2 is true

and finally you can set your own variables!.

set

<!--#set var="Title" value="Apache RTFM!" -->

Which bring be to a complete example, namely the Apache RTFM standard template.

<!--#set var="Title" value="Your Title Goes Here" -->
<!--#include file="rtfm_header.shtml" -->

<!--#include file="you new html file.html" -->

<!-- set, delete, or modify as required -->
<!--#set var="Previous" value="<a href=\"????.shtml\">Previous file</a>" -->
<!--#set var="Next" value="<a href=\"????.shtml\">Next File</a>" -->

<!--#include file="rtfm_footer.shtml" -->

The rtfm_header.shtml looks like

	<html>
	<head>
	<title>
	<!--#echo var="Title"-->
	</title>
		.
		.

and the rtfm_footer.shtml

	<center>
	<hr width=50%>
	<!--#if expr="\"$Previous\" != \"\" " -->
		<!--#echo var="Previous" -->
		 
	<!--#endif -->
	<a href="rtfm.shtml">RTFM Index</a>
	<!--#if expr="\"$Next\" != \"\" " -->
		 
		<!--#echo var="Next" -->
	<!--#endif -->
	<hr width=50%>

	<!--#config timefmt="%A %B %d %Y"-->

	<h6>
	<a href="/misc/copyright.html">Copyright</a> © 
	1998 Open Source Migrations ltd. All Rights Reserved.<br>
	Apache RTFM last updated <!--#flastmod virtual="rtfm.shtml"-->
	</h6>
	</center>
	</body></html>

So what's it all do?

First we get the title of each document printed. We set the title for each document in the template file.

<!--#set var="Title" value="eXtended SSI" -->
<!--#include file="rtfm_header.shtml" -->

And in the rtfm_header.shtml file

	<html>
	<head>
	<title>
	<!--#echo var="Title"-->
	</title>

Prints it out the doucment title in the correct context.

Next we use want to create a mini-navigation menu in the footer. The lines

<!--#set var="Previous" value="<a href=\"include_ssi.shtml\">
Including files with SSIs</a>" -->

In the template file set up the footer information so we can point at the previous document in this section.

The footer file then conditionally displays the parts of the menu we have setup in the template.

	<!--#if expr="\"$Previous\" != \"\" " -->
		<!--#echo var="Previous" -->
		&nbsp;
	<!--#endif -->

In the footer we check to see of $Previous is not equal to "" (an empty string) If this is TRUE, the footer prints out a link to the previous section. The same type of test is used for creating a link to the Next section.

The pragma expr="....." must contain "'s, but there might be spaces in the string $Previous so we enclose in in quotes, but since there are already inside a set of quotes (expr="...."), we need to "escape" these inner quotes.

String1
\"$Previous\"  and String2
\"\"

Just for fun

Including files with SSIs RTFM Index SSI Colophon