CGI::Push(3) CGI::Push(3)
CGI::Push - Simple Interface to Server Push
use CGI::Push qw(:standard);
do_push(-next_page=>\&next_page,
-last_page=>\&last_page,
-delay=>0.5);
sub next_page {
my($q,$counter) = @_;
return undef if $counter >= 10;
return start_html('Test'),
h1('Visible'),"\n",
"This page has been called ", strong($counter)," times",
end_html();
}
sub last_page {
my($q,$counter) = @_;
return start_html('Done'),
h1('Finished'),
strong($counter),' iterations.',
end_html;
}
CGI::Push is a subclass of the CGI object created by CGI.pm. It is
specialized for server push operations, which allow you to create
animated pages whose content changes at regular intervals.
You provide CGI::Push with a pointer to a subroutine that will draw one
page. Every time your subroutine is called, it generates a new page.
The contents of the page will be transmitted to the browser in such a way
that it will replace what was there beforehand. The technique will work
with HTML pages as well as with graphics files, allowing you to create
animated GIFs.
USING CGI::Push
CGI::Push adds one new method to the standard CGI suite, do_push(). When
you call this method, you pass it a reference to a subroutine that is
responsible for drawing each new page, an interval delay, and an optional
subroutine for drawing the last page. Other optional parameters include
most of those recognized by the CGI header() method.
You may call do_push() in the object oriented manner or not, as you
prefer:
Page 1
CGI::Push(3) CGI::Push(3)
use CGI::Push;
$q = new CGI::Push;
$q->do_push(-next_page=>\&draw_a_page);
-or
use CGI::Push qw(:standard);
do_push(-next_page=>\&draw_a_page);
Parameters are as follows:
-next_page
do_push(-next_page=>\&my_draw_routine);
This required parameter points to a reference to a subroutine
responsible for drawing each new page. The subroutine should expect
two parameters consisting of the CGI object and a counter indicating
the number of times the subroutine has been called. It should return
the contents of the page as an array of one or more items to print.
It can return a false value (or an empty array) in order to abort the
redrawing loop and print out the final page (if any)
sub my_draw_routine {
my($q,$counter) = @_;
return undef if $counter > 100;
return start_html('testing'),
h1('testing'),
"This page called $counter times";
}
-last_page
This optional parameter points to a reference to the subroutine
responsible for drawing the last page of the series. It is called
after the -next_page routine returns a false value. The subroutine
itself should have exactly the same calling conventions as the
-next_page routine.
-type
This optional parameter indicates the content type of each page. It
defaults to "text/html". Currently, server push of heterogeneous
document types is not supported.
-delay
This indicates the delay, in seconds, between frames. Smaller delays
refresh the page faster. Fractional values are allowed.
If not specified, -delay will default to 1 second
Page 2
CGI::Push(3) CGI::Push(3)
-cookie, -target, -expires
These have the same meaning as the like-named parameters in
CGI::header().
INSTALLING CGI::Push SCRIPTS
Server push scripts must be installed as no-parsed-header (NPH) scripts
in order to work correctly. On Unix systems, this is most often
accomplished by prefixing the script's name with "nph-". Recognition of
NPH scripts happens automatically with WebSTAR and Microsoft IIS. Users
of other servers should see their documentation for help.
This is a new module. It hasn't been extensively tested.
be used and modified freely, but I do request that this copyright notice
remain attached to the file. You may modify this module as you wish, but
if you redistribute a modified version, please attach a note listing the
modifications you have made.
Address bug reports and comments to: [email protected]
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the CGI::Carp manpage, the CGI manpage
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