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Perl Modules

Perl Modules. Darby Tien-Hao Chang Department of Electrical Engineering, National Cheng Kung University. CPAN Comprehensive Perl Archive Network. http://search.cpan.org/. CGI.pm Simple Common Gateway Interface class. You can find some resources from CPAN: Source Typical usage

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Perl Modules

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  1. Perl Modules Darby Tien-Hao Chang Department of Electrical Engineering, National Cheng Kung University

  2. CPANComprehensive Perl Archive Network • http://search.cpan.org/

  3. CGI.pmSimple Common Gateway Interface class • You can find some resources from CPAN: • Source • Typical usage • Function-by-function description • How do I know the module name “CGI”?

  4. LWP::SimpleSimple procedural interface to LWP • So, what is LWP? • The World-Wide Web library for Perl • get($url) • How do we get a POST web page? • head($url) • getprint($url) • getstore($url, $file) • mirror($url, $file) • is_success($rc) • is_error($rc)

  5. How to POST? • #!/usr/bin/perl -w • # dependent modules • use strict; • use LWP::UserAgent; • my $url = "http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl"; • my @form = { • "pdbcode" => "1bck" • }; • my $ua = new LWP::UserAgent; • my $response = $ua->post( $url, \@form ); • if ( $response->is_success ) { • print $response->content; # or whatever • } else { • die $response->status_line; • }

  6. Compare to the GET example • #!/usr/bin/perl -w • # dependent modules • use strict; • use LWP::Simple; • my $url = "http://www.pdb.org/pdb/navbarsearch.do?inputQuickSearch=1bck"; • my $web = &get( $url ); • print "$web“;

  7. What is LWP::UserAgent? • It’s a browser! • It contain almost everything of your browser… if Perl can mimic • LWP Library version number and documentation • LWP::MediaTypes MIME types configuration (text/html etc.) • LWP::Debug Debug logging module • LWP::Simple Simplified procedural interface for common functions • HTTP::Status HTTP status code (200 OK etc) • HTTP::Date Date parsing module for HTTP date formats • HTTP::Negotiate HTTP content negotiation calculation • File::Listing Parse directory listings • HTML::Form Processing for <form>s in HTML documents

  8. LWP, LWP::Simple and LWP::UserAgent, what a mess! • You can include LWP directly • use LWP; • There are some clues in the CPAN • http://search.cpan.org/~gaas/libwww-perl-5.805/lib/LWP/Simple.pm • http://search.cpan.org/~gaas/libwww-perl-5.805/lib/LWP.pm

  9. Multi-steps extraction • #!/usr/bin/perl -w • use LWP::Simple; • my $term = “棒球"; • my $url = "http://tw.sports.yahoo.com/bj2008/schedule.html"; • my $web = &get( $url ); • $web =~ /href=([^>"]+)>$term/ or die; • $url = "http://tw.sports.yahoo.com/bj2008/$1"; • $web = &get( $url );

  10. A more browser-like Perl moduleWWW::Mechanize • use WWW::Mechanize; • my $mech = WWW::Mechanize->new(); • $mech->get( $url ); • $mech->follow_link( n => 3 ); • $mech->follow_link( text_regex => qr/download this/i ); • $mech->follow_link( url => 'http://host.com/index.html' ); • $mech->submit_form( • form_number => 3, • fields => { • username => 'mungo', • password => 'lost-and-alone', • } • ); • $mech->submit_form( • form_name => 'search', • fields => { • query => 'pot of gold', • }, • button => 'Search Now‘ • );

  11. Consider a CGI program to show some server information • #!/usr/bin/perl -w • print “Content-type: text/html\n\n”; • print “<html>”; • print “<head>”; • print “<title>Test Template</title>”; • print “</head>”; • print “<body>”; • print “My Home Directory is $ENV{HOME}<br />”; • print “My Path is set to $ENV{PATH}”; • print “</body>”; • print “</html>”;

  12. Now suppose that we have a wizard-like web application • Step1.html • Input your first name, last name and e-mail • Step2.pl • Validate the e-mail and one more question • Step3.pl • Show the final page

  13. How will you design the three page? • They are supposed to be very similar • And there could be numerous redundant code

  14. One more Perl module to help CGI.pmHTML::Template • <html> • <head> • <title>Test Template</title> • </head> • <body> • My Home Directory is <TMPL_VAR NAME=HOME><br /> • My Path is set to <TMPL_VAR NAME=PATH> • </body> • </html> • #!/usr/bin/perl -w • use HTML::Template; • # open the html template • my $template = HTML::Template->new(filename => 'test.html'); • # fill in some parameters $template->param(HOME => $ENV{HOME}); • $template->param(PATH => $ENV{PATH}); • # send the obligatory Content-Type and print the template output • print "Content-Type: text/html\n\n", $template->output;

  15. The tags • TMPL_VAR • <TMPL_VAR NAME="PARAMETER_NAME"> • TMPL_LOOP • <TMPL_LOOP NAME=EMPLOYEE_INFO> • Name: <TMPL_VAR NAME=NAME><br/> • Job: <TMPL_VAR NAME=JOB> • </TMPL_LOOP> • $template->param(EMPLOYEE_INFO => [ • { name => 'Sam', job => 'programmer' }, • { name => 'Steve', job => 'soda jerk' }, • ] ); • print $template->output(); • TMPL_IF, TMPL_ELSE

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