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Diffstat (limited to 'lib/CGI/Push.pm')
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diff --git a/lib/CGI/Push.pm b/lib/CGI/Push.pm new file mode 100644 index 0000000000..11421a7f23 --- /dev/null +++ b/lib/CGI/Push.pm @@ -0,0 +1,239 @@ +package CGI::Push; + +# See the bottom of this file for the POD documentation. Search for the +# string '=head'. + +# You can run this file through either pod2man or pod2html to produce pretty +# documentation in manual or html file format (these utilities are part of the +# Perl 5 distribution). + +# Copyright 1995,1996, Lincoln D. Stein. All rights reserved. +# It may 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. + +# The most recent version and complete docs are available at: +# http://www.genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html +# ftp://ftp-genome.wi.mit.edu/pub/software/WWW/ + +$CGI::Push::VERSION='1.00'; +use CGI; +@ISA = ('CGI'); + +# add do_push() to exported tags +push(@{$CGI::EXPORT_TAGS{':standard'}},'do_push'); + +sub do_push { + my ($self,@p) = CGI::self_or_CGI(@_); + + # unbuffer output + $| = 1; + srand; + my ($random) = rand()*1E16; + my ($boundary) = "----------------------------------$random"; + + my (@header); + my ($type,$callback,$delay,$last_page,$cookie,$target,$expires,@other) = + $self->rearrange([TYPE,NEXT_PAGE,DELAY,LAST_PAGE,[COOKIE,COOKIES],TARGET,EXPIRES],@p); + $type = 'text/html' unless $type; + $callback = \&simple_counter unless $callback && ref($callback) eq 'CODE'; + $delay = 1 unless defined($delay); + + my(@o); + foreach (@other) { push(@o,split("=")); } + push(@o,'-Target'=>$target) if defined($target); + push(@o,'-Cookie'=>$cookie) if defined($cookie); + push(@o,'-Type'=>"multipart/x-mixed-replace; boundary=$boundary"); + push(@o,'-Server'=>"CGI.pm Push Module"); + push(@o,'-Status'=>'200 OK'); + push(@o,'-nph'=>1); + print $self->header(@o); + print "${boundary}$CGI::CRLF"; + + # now we enter a little loop + my @contents; + while (1) { + last unless (@contents = &$callback($self,++$COUNTER)) && defined($contents[0]); + print "Content-type: ${type}$CGI::CRLF$CGI::CRLF"; + print @contents,"$CGI::CRLF"; + print "${boundary}$CGI::CRLF"; + do_sleep($delay) if $delay; + } + print "Content-type: ${type}$CGI::CRLF$CGI::CRLF", + &$last_page($self,++$COUNTER), + "$CGI::CRLF${boundary}$CGI::CRLF" + if $last_page && ref($last_page) eq 'CODE'; +} + +sub simple_counter { + my ($self,$count) = @_; + return ( + CGI->start_html("CGI::Push Default Counter"), + CGI->h1("CGI::Push Default Counter"), + "This page has been updated ",CGI->strong($count)," times.", + CGI->hr(), + CGI->a({'-href'=>'http://www.genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html'},'CGI.pm home page'), + CGI->end_html + ); +} + +sub do_sleep { + my $delay = shift; + if ( ($delay >= 1) && ($delay!~/\./) ){ + sleep($delay); + } else { + select(undef,undef,undef,$delay); + } +} + +1; + +=head1 NAME + +CGI::Push - Simple Interface to Server Push + +=head1 SYNOPSIS + + use CGI::Push qw(:standard); + + do_push(-next_page=>\&next_page, + -last_page=>\&last_page, + -delay=>0.5); + + sub next_page { + my($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; + } + +=head1 DESCRIPTION + +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. + +=head1 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: + + use CGI::Push; + $q = new CGI::Push; + $q->do_push(-next_page=>\&draw_a_page); + + -or- + + use CGI::Push qw(:standard); + do_push(-next_page=>\&draw_a_page); + +Parameters are as follows: + +=over 4 + +=item -next_page + + do_push(-next_page=>\&my_draw_routine); + +This required parameter points to a reference to a subroutine responsible for +drawing each new page. The subroutine should expect two parameters +consisting of the CGI object and a counter indicating the number +of times the subroutine has been called. It should return the +contents of the page as an B<array> of one or more items to print. +It can return a false value (or an empty array) in order to abort the +redrawing loop and print out the final page (if any) + + sub my_draw_routine { + my($q,$counter) = @_; + return undef if $counter > 100; + return start_html('testing'), + h1('testing'), + "This page called $counter times"; + } + +=item -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. + +=item -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. + +=item -delay + +This indicates the delay, in seconds, between frames. Smaller delays +refresh the page faster. Fractional values are allowed. + +B<If not specified, -delay will default to 1 second> + +=item -cookie, -target, -expires + +These have the same meaning as the like-named parameters in +CGI::header(). + +=back + +=head1 INSTALLING CGI::Push SCRIPTS + +Server push scripts B<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. + +=head1 CAVEATS + +This is a new module. It hasn't been extensively tested. + +=head1 AUTHOR INFORMATION + +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: +lstein@genome.wi.mit.edu + +=head1 BUGS + +This section intentionally left blank. + +=head1 SEE ALSO + +L<CGI::Carp>, L<CGI> + +=cut + |