File Coverage

blib/lib/CGI/Push.pm
Criterion Covered Total %
statement 49 54 90.7
branch 20 32 62.5
condition 5 12 41.7
subroutine 5 6 83.3
pod 0 4 0.0
total 79 108 73.1


line stmt bran cond sub pod time code
1             package CGI::Push;
2              
3             # See the bottom of this file for the POD documentation. Search for the
4             # string '=head'.
5              
6             # You can run this file through either pod2man or pod2html to produce pretty
7             # documentation in manual or html file format (these utilities are part of the
8             # Perl 5 distribution).
9              
10             # Copyright 1995-2000, Lincoln D. Stein. All rights reserved.
11             # It may be used and modified freely, but I do request that this copyright
12             # notice remain attached to the file. You may modify this module as you
13             # wish, but if you redistribute a modified version, please attach a note
14             # listing the modifications you have made.
15              
16             # The most recent version and complete docs are available at:
17             # http://stein.cshl.org/WWW/software/CGI/
18              
19             $CGI::Push::VERSION='1.04';
20 1     1   25 use CGI;
  1         154  
  1         20  
21 1     1   19 use CGI::Util 'rearrange';
  1         9  
  1         19  
22             @ISA = ('CGI');
23              
24             $CGI::DefaultClass = 'CGI::Push';
25             $CGI::Push::AutoloadClass = 'CGI';
26              
27             # add do_push() and push_delay() to exported tags
28             push(@{$CGI::EXPORT_TAGS{':standard'}},'do_push','push_delay');
29              
30             sub do_push {
31 3     3 0 35     my ($self,@p) = CGI::self_or_default(@_);
32              
33             # unbuffer output
34 3         33     $| = 1;
35 3         140     srand;
36 3         120     my ($random) = sprintf("%08.0f",rand()*1E8);
37 3         31     my ($boundary) = "----=_NeXtPaRt$random";
38              
39 3         24     my (@header);
40 3         55     my ($type,$callback,$delay,$last_page,$cookie,$target,$expires,$nph,@other) = rearrange([TYPE,NEXT_PAGE,DELAY,LAST_PAGE,[COOKIE,COOKIES],TARGET,EXPIRES,NPH],@p);
41 3 100       39     $type = 'text/html' unless $type;
42 3 50 33     93     $callback = \&simple_counter unless $callback && ref($callback) eq 'CODE';
43 3 50       29     $delay = 1 unless defined($delay);
44 3         31     $self->push_delay($delay);
45 3 50       29     $nph = 1 unless defined($nph);
46              
47 3         24     my(@o);
48 3         29     foreach (@other) { push(@o,split("=")); }
  0         0  
49 3 50       29     push(@o,'-Target'=>$target) if defined($target);
50 3 50       30     push(@o,'-Cookie'=>$cookie) if defined($cookie);
51 3         33     push(@o,'-Type'=>"multipart/x-mixed-replace;boundary=\"$boundary\"");
52 3 50       33     push(@o,'-Server'=>"CGI.pm Push Module") if $nph;
53 3         29     push(@o,'-Status'=>'200 OK');
54 3 50       32     push(@o,'-nph'=>1) if $nph;
55 3         47     print $self->header(@o);
56              
57 3         84     $boundary = "$CGI::CRLF--$boundary";
58              
59 3         33     print "WARNING: YOUR BROWSER DOESN'T SUPPORT THIS SERVER-PUSH TECHNOLOGY.${boundary}$CGI::CRLF";
60              
61 3         64     my (@contents) = &$callback($self,++$COUNTER);
62              
63             # now we enter a little loop
64 3         41     while (1) {
65 4 100       42         print "Content-type: ${type}$CGI::CRLF$CGI::CRLF" unless $type =~ /^dynamic|heterogeneous$/i;
66 4         43         print @contents;
67 4         86         @contents = &$callback($self,++$COUNTER);
68 4 100 66     105         if ((@contents) && defined($contents[0])) {
69 1         11             print "${boundary}$CGI::CRLF";
70 1 50       22             do_sleep($self->push_delay()) if $self->push_delay();
71                     } else {
72 3 100 66     53             if ($last_page && ref($last_page) eq 'CODE') {
73 2         20                 print "${boundary}$CGI::CRLF";
74 2 50       74                 do_sleep($self->push_delay()) if $self->push_delay();
75 2 50       21                 print "Content-type: ${type}$CGI::CRLF$CGI::CRLF" unless $type =~ /^dynamic|heterogeneous$/i;
76 2         42                 print &$last_page($self,$COUNTER);
77                         }
78 3         31             print "${boundary}--$CGI::CRLF";
79 3         57             last;
80                     }
81                 }
82 3         31     print "WARNING: YOUR BROWSER DOESN'T SUPPORT THIS SERVER-PUSH TECHNOLOGY.$CGI::CRLF";
83             }
84              
85             sub simple_counter {
86 1     1 0 11     my ($self,$count) = @_;
87 1         24     return $self->start_html("CGI::Push Default Counter"),
88                        $self->h1("CGI::Push Default Counter"),
89                        "This page has been updated ",$self->strong($count)," times.",
90                        $self->hr(),
91                        $self->a({'-href'=>'http://www.genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html'},'CGI.pm home page'),
92                        $self->end_html;
93             }
94              
95             sub do_sleep {
96 0     0 0 0     my $delay = shift;
97 0 0 0     0     if ( ($delay >= 1) && ($delay!~/\./) ){
98 0         0         sleep($delay);
99                 } else {
100 0         0         select(undef,undef,undef,$delay);
101                 }
102             }
103              
104             sub push_delay {
105 8     8 0 149     my ($self,$delay) = CGI::self_or_default(@_);
106 8 100       107     return defined($delay) ? $self->{'.delay'} =
107                     $delay : $self->{'.delay'};
108             }
109              
110             1;
111              
112             =head1 NAME
113            
114             CGI::Push - Simple Interface to Server Push
115            
116             =head1 SYNOPSIS
117            
118             use CGI::Push qw(:standard);
119            
120             do_push(-next_page=>\&next_page,
121             -last_page=>\&last_page,
122             -delay=>0.5);
123            
124             sub next_page {
125             my($q,$counter) = @_;
126             return undef if $counter >= 10;
127             return start_html('Test'),
128             h1('Visible'),"\n",
129             "This page has been called ", strong($counter)," times",
130             end_html();
131             }
132            
133             sub last_page {
134             my($q,$counter) = @_;
135             return start_html('Done'),
136             h1('Finished'),
137             strong($counter - 1),' iterations.',
138             end_html;
139             }
140            
141             =head1 DESCRIPTION
142            
143             CGI::Push is a subclass of the CGI object created by CGI.pm. It is
144             specialized for server push operations, which allow you to create
145             animated pages whose content changes at regular intervals.
146            
147             You provide CGI::Push with a pointer to a subroutine that will draw
148             one page. Every time your subroutine is called, it generates a new
149             page. The contents of the page will be transmitted to the browser
150             in such a way that it will replace what was there beforehand. The
151             technique will work with HTML pages as well as with graphics files,
152             allowing you to create animated GIFs.
153            
154             Only Netscape Navigator supports server push. Internet Explorer
155             browsers do not.
156            
157             =head1 USING CGI::Push
158            
159             CGI::Push adds one new method to the standard CGI suite, do_push().
160             When you call this method, you pass it a reference to a subroutine
161             that is responsible for drawing each new page, an interval delay, and
162             an optional subroutine for drawing the last page. Other optional
163             parameters include most of those recognized by the CGI header()
164             method.
165            
166             You may call do_push() in the object oriented manner or not, as you
167             prefer:
168            
169             use CGI::Push;
170             $q = new CGI::Push;
171             $q->do_push(-next_page=>\&draw_a_page);
172            
173             -or-
174            
175             use CGI::Push qw(:standard);
176             do_push(-next_page=>\&draw_a_page);
177            
178             Parameters are as follows:
179            
180             =over 4
181            
182             =item -next_page
183            
184             do_push(-next_page=>\&my_draw_routine);
185            
186             This required parameter points to a reference to a subroutine responsible for
187             drawing each new page. The subroutine should expect two parameters
188             consisting of the CGI object and a counter indicating the number
189             of times the subroutine has been called. It should return the
190             contents of the page as an B<array> of one or more items to print.
191             It can return a false value (or an empty array) in order to abort the
192             redrawing loop and print out the final page (if any)
193            
194             sub my_draw_routine {
195             my($q,$counter) = @_;
196             return undef if $counter > 100;
197             return start_html('testing'),
198             h1('testing'),
199             "This page called $counter times";
200             }
201            
202             You are of course free to refer to create and use global variables
203             within your draw routine in order to achieve special effects.
204            
205             =item -last_page
206            
207             This optional parameter points to a reference to the subroutine
208             responsible for drawing the last page of the series. It is called
209             after the -next_page routine returns a false value. The subroutine
210             itself should have exactly the same calling conventions as the
211             -next_page routine.
212            
213             =item -type
214            
215             This optional parameter indicates the content type of each page. It
216             defaults to "text/html". Normally the module assumes that each page
217             is of a homogenous MIME type. However if you provide either of the
218             magic values "heterogeneous" or "dynamic" (the latter provided for the
219             convenience of those who hate long parameter names), you can specify
220             the MIME type -- and other header fields -- on a per-page basis. See
221             "heterogeneous pages" for more details.
222            
223             =item -delay
224            
225             This indicates the delay, in seconds, between frames. Smaller delays
226             refresh the page faster. Fractional values are allowed.
227            
228             B<If not specified, -delay will default to 1 second>
229            
230             =item -cookie, -target, -expires, -nph
231            
232             These have the same meaning as the like-named parameters in
233             CGI::header().
234            
235             If not specified, -nph will default to 1 (as needed for many servers, see below).
236            
237             =back
238            
239             =head2 Heterogeneous Pages
240            
241             Ordinarily all pages displayed by CGI::Push share a common MIME type.
242             However by providing a value of "heterogeneous" or "dynamic" in the
243             do_push() -type parameter, you can specify the MIME type of each page
244             on a case-by-case basis.
245            
246             If you use this option, you will be responsible for producing the
247             HTTP header for each page. Simply modify your draw routine to
248             look like this:
249            
250             sub my_draw_routine {
251             my($q,$counter) = @_;
252             return header('text/html'), # note we're producing the header here
253             start_html('testing'),
254             h1('testing'),
255             "This page called $counter times";
256             }
257            
258             You can add any header fields that you like, but some (cookies and
259             status fields included) may not be interpreted by the browser. One
260             interesting effect is to display a series of pages, then, after the
261             last page, to redirect the browser to a new URL. Because redirect()
262             does b<not> work, the easiest way is with a -refresh header field,
263             as shown below:
264            
265             sub my_draw_routine {
266             my($q,$counter) = @_;
267             return undef if $counter > 10;
268             return header('text/html'), # note we're producing the header here
269             start_html('testing'),
270             h1('testing'),
271             "This page called $counter times";
272             }
273            
274             sub my_last_page {
275             return header(-refresh=>'5; URL=http://somewhere.else/finished.html',
276             -type=>'text/html'),
277             start_html('Moved'),
278             h1('This is the last page'),
279             'Goodbye!'
280             hr,
281             end_html;
282             }
283            
284             =head2 Changing the Page Delay on the Fly
285            
286             If you would like to control the delay between pages on a page-by-page
287             basis, call push_delay() from within your draw routine. push_delay()
288             takes a single numeric argument representing the number of seconds you
289             wish to delay after the current page is displayed and before
290             displaying the next one. The delay may be fractional. Without
291             parameters, push_delay() just returns the current delay.
292            
293             =head1 INSTALLING CGI::Push SCRIPTS
294            
295             Server push scripts must be installed as no-parsed-header (NPH)
296             scripts in order to work correctly on many servers. On Unix systems,
297             this is most often accomplished by prefixing the script's name with "nph-".
298             Recognition of NPH scripts happens automatically with WebSTAR and
299             Microsoft IIS. Users of other servers should see their documentation
300             for help.
301            
302             Apache web server from version 1.3b2 on does not need server
303             push scripts installed as NPH scripts: the -nph parameter to do_push()
304             may be set to a false value to disable the extra headers needed by an
305             NPH script.
306            
307             =head1 AUTHOR INFORMATION
308            
309             Copyright 1995-1998, Lincoln D. Stein. All rights reserved.
310            
311             This library is free software; you can redistribute it and/or modify
312             it under the same terms as Perl itself.
313            
314             Address bug reports and comments to: lstein@cshl.org
315            
316             =head1 BUGS
317            
318             This section intentionally left blank.
319            
320             =head1 SEE ALSO
321            
322             L<CGI::Carp>, L<CGI>
323            
324             =cut
325              
326