SSI(3)
NAME
Apache::SSI - Implement Server Side Includes in Perl
SYNOPSIS
In httpd.conf:
<Files *.phtml> # or whatever
SetHandler perl-script
PerlHandler Apache::SSI
</Files>
You may wish to subclass Apache::SSI for your own extensions. If so,
compile mod_perl with PERL_METHOD_HANDLERS=1 (so you can use object-
oriented inheritance), and create a module like this:
package MySSI;
use Apache::SSI ();
@ISA = qw(Apache::SSI);
#embedded syntax:
#<!--#something param=value -->
sub ssi_something {
my($self, $attr) = @_;
my $cmd = $attr->{param};
...
return $a_string;
}
Then in httpd.conf:
<Files *.phtml>
SetHandler perl-script
PerlHandler MySSI
</Files>
DESCRIPTION
Apache::SSI implements the functionality of mod_include for handling
server-parsed html documents. It runs under Apache's mod_perl.
In my mind, there are two main reasons you might want to use this mod-
ule: you can sub-class it to implement your own custom SSI directives,
and/or you can parse the output of other mod_perl handlers, or send the
SSI output through another handler (use Apache::Filter to do this).
Each SSI directive is handled by an Apache::SSI method with the prefix
"ssi_". For example, <!--#printenv--> is handled by the ssi_printenv
method. attribute=value pairs inside the SSI tags are parsed and
passed to the method in a hash reference.
'Echo' directives are handled by the ssi_echo method, which delegates
lookup to methods with the prefix "echo_". For instance, <!--#echo
var=DOCUMENT_NAME--> is handled by the echo_DOCUMENT_NAME method.
You can customize behavior by inheriting from Apache::SSI and overrid-
ing 'ssi_*' and 'echo_*' methods, or writing new ones.
SSI Directives
This module supports the same directives as mod_include. At least,
that's the goal. =) For methods listed below but not documented,
please see mod_include's online documentation at http://www.apache.org/
.
* config
* echo
* exec
* fsize
* flastmod
* include
* printenv
* set
* perl
There are two ways to call a Perl function, and two ways to supply
it with arguments. The function can be specified either as an
anonymous subroutine reference, or as the name of a function
defined elsewhere:
<!--#perl sub="sub { localtime() }"-->
<!--#perl sub="time::now"-->
If the 'sub' argument matches the regular expression
/^\s*sub[^\w:]/, it is assumed to be a subroutine reference. Oth-
erwise it's assumed to be the name of a function. In the latter
case, the string "main::" will be prepended to the function name if
the name doesn't contain "::" (this forces the function to be in
the main package, or a package you specify). Note that it's a
pretty bad idea to put your code in the main package, so I only
halfheartedly endorse this feature.
In general, it will be slower to use anonymous subroutines, because
each one has to be eval()'ed and there is no caching. For best
results, pre-load any code you need in the parent process, then
call it by name.
If you're calling a subroutine like "&Package::SubPack::handler",
you can omit the "handler" portion, making your directive like
this:
<!--#perl sub="Package::Subpack"-->
If you want to supply a list of arguments to the function, you use
either the "arg" or the "args" parameter:
<!--#perl sub="sub {$_[0] * 7}" arg=7-->
<!--#perl sub=holy::matrimony arg=Hi arg=Lois-->
<!--#perl sub=holy::matrimony args=Hi,Lois-->
The "args" parameter will simply split on commas, meaning that cur-
rently there's no way to embed a comma in arguments passed via the
"args" parameter. Use the "arg" parameter for this.
If you give a key-value pair and the key is not 'sub', 'arg',
'args', or 'pass_request' (see below), then your routine will be
passed both the key and the value. This lets you pass a hash of
key-value pairs to your function:
<!--#perl sub=holy::matrimony groom=Hi bride=Lois-->
Will call &holy::matrimony('groom', 'Hi', 'bride', 'Lois');
As of version 1.95, we pass the current Apache request object ($r)
as the first argument to the function. To turn off this behavior,
give the key-value pair 'pass_request=no', or put 'PerlSetVar
SSIPerlPass_Request no' in your server's config file.
See "http://perl.apache.org/src/mod_perl.html" for more information
on Perl SSI calls.
* if
* elif
* else
* endif
These four directives can be used just like in "mod_include", with
one important difference: the boolean expression is evaluated using
Perl's eval(). This means you use "==" or "eq" instead of "=" to
test equality. It also means you can use pre-loaded Perl subrou-
tines in the conditions:
<!--#if expr="&Movies::is_by_Coen_Brothers($MOVIE)"-->
This movie is by the Coen Brothers.
<!--#else-->
This movie is not by the Coen Brothers.
<!--#endif-->
It can't handle very sophistocated Perl though, because it manually
looks for variables (of the form $var or ${var}, just like
"mod_include"), and will get tripped up on expressions like
$object->method or $hash{'key'}. I'll welcome any suggestions for
how to allow arbitrary Perl expressions while still filling in
Apache variables.
CHAINING HANDLERS
There are two fairly simple ways for this module to exist in a stacked
handler chain. The first uses "Apache::Filter", and your httpd.conf
would look something like this:
PerlModule Apache::Filter
PerlModule Apache::SSI
PerlModule My::BeforeSSI
PerlModule My::AfterSSI
<Files ~ "\.ssi$">
SetHandler perl-script
PerlSetVar Filter On
PerlHandler My::BeforeSSI Apache::SSI My::AfterSSI
</Files>
The "PerlSetVar Filter On" directive tells the three stacked handlers
that they should use their filtering mode. It's mandatory.
The second uses "Apache::OutputChain", and your httpd.conf would look
something like this:
PerlModule Apache::OutputChain
PerlModule Apache::SSIChain
PerlModule My::BeforeSSI
PerlModule My::AfterSSI
<Files ~ "\.ssi$">
SetHandler perl-script
PerlHandler Apache::OutputChain My::AfterSSI Apache::SSIChain My::BeforeSSI
</Files>
Note that the order of handlers is reversed in the two different meth-
ods. One reason I wrote "Apache::Filter" is to get the order to be
more intuitive. Another reason is that "Apache::SSI" itself can be
used in a handler stack using "Apache::Filter", whereas it needs to be
wrapped in "Apache::SSIChain" to be used with "Apache::OutputChain".
Please see the documentation for "Apache::OutputChain" and
"Apache::Filter" for more specific information. And look at the note
in CAVEATS too.
CAVEATS
* When chaining handlers via Apache::Filter, if you use <!--#include
...--> or <!--#exec cgi=...-->, then Apache::SSI must be the last fil-
ter in the chain. This is because Apache::SSI uses
$r->lookup_uri(...)->run to include the files, and this sends the out-
put through C's stdout rather than Perl's STDOUT. Thus Apache::Filter
can't catch it and filter it.
If Apache::SSI is the last filter in the chain, or if you stick to sim-
pler SSI directives like <!--#fsize-->, <!--#flastmod-->, etc. you'll
be fine.
* Currently, the way <!--#echo var=whatever--> looks for variables is
to first try $r->subprocess_env, then try %ENV, then the five extra
environment variables mod_include supplies. Is this the correct order?
TO DO
Revisit http://www.apache.org/docs/mod/mod_include.html and see what
else there I can implement.
It would be nice to have a "PerlSetVar ASSI_Subrequests 0|1" option
that would let you choose between executing a full-blown subrequest
when including a file, or just opening it and printing it.
I'd like to know how to use Apache::test for the real.t test.
SEE ALSO
mod_include, mod_perl(3), Apache(3), HTML::Embperl(3),
Apache::ePerl(3), Apache::OutputChain(3)
AUTHOR
Ken Williams ken@forum.swarthmore.edu
Concept based on original version by Doug MacEachern dougm@osf.org .
Implementation different.
COPYRIGHT
Copyright 1998 Swarthmore College. All rights reserved.
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.8.6 2005-02-25 SSI(3)
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