This document discusses developing Rich Internet Applications (RIAs) using the Ext JS JavaScript framework and the Perl RPC::ExtDirect module. It describes how RIAs work by handling all client interaction in JavaScript, communicating with the server asynchronously via AJAX calls. The Ext JS framework provides cross-browser compatibility, clean MVC architecture and low server overhead. RPC::ExtDirect allows Perl to serve as the backend, implementing the Ext.Direct protocol to integrate existing Perl code and work on any platform. Examples are given of using RPC::ExtDirect in a CGI application to publish APIs and route requests.

1. Developing Rich Internet
Applications with Perl and JavaScript
San Diego.pm talk
Apr 19 2012

2. Web application evolution
• Once upon a time, there was a static
page
• Then came CGI scripts
• Then came client side scripting
• Then came AJAX and asynchronous calls
• What next?

3. Introducing RIA
• One possible answer: RIAs
• Stands for: Rich Internet Applications
• Many ways to develop, many frameworks
• I have been exploring Ext JS framework
for JavaScript

4. How does it work?
• No (or minimal) HTML/JavaScript
generation on server side
• All client interaction is done in JavaScript
• All middleware/database stuff is done on
the server side (platform agnostic)
• Communication is done AJAX style, using
Ext.Direct RPC protocol

5. Ext JS Advantages
• Cross browser compatibility (even IE6)
• Really good code and issue separation
• Very low overhead on server side
• Very low traffic (only data goes on wire)
• Clean MVC architecture – easier to
develop
• But wait, where’s Perl?

6. Perl shines through
• Perl can be used to develop server side
• Does things it does best
• Works anywhere
• Really easy to plug in existing code
• Uses RPC::ExtDirect as the glue

7. Introducing RPC::ExtDirect
• Abstract module that implements
Ext.Direct protocol
• Has gateways for CGI, Plack (maybe
mod_perl in future)
• Compatible down to 5.6.0
• Only one non-core dependency:
JSON.pm (can be pure Perl)

8. Using RPC::ExtDirect
1. Declare Action (Class, Namespace):
package Foo::Bar;
use RPC::ExtDirect Action => 'Fubar';
sub foo : ExtDirect(2) {
my ($class, $arg1, $arg2) = @_;
# do something, store results in scalar
my $result = ...;
return $result;
}

9. Using RPC::ExtDirect, cont.
2. CGI example part 1, API publisher (api.cgi):
use CGI::ExtDirect;
use My::ExtDirect::Published::Module::Foo;
use My::ExtDirect::Published::Module::Bar;
my $direct = CGI::ExtDirect−>new();
print $direct−>api(); # Prints full HTTP response

10. Using RPC::ExtDirect, cont.
1. CGI example part 2: request router
use CGI::ExtDirect;
use RPC::ExtDirect::API api_path => '/extdirect_api',
router_path => '/extdirect_router’;
use My::ExtDirect::Published::Module::Foo;
use My::ExtDirect::Published::Module::Bar;
my $direct = CGI::ExtDirect−>new({ debug => 1 });
print $direct−>route(); # Prints full HTTP response

11. Possible applications
• New stuff from scratch, easy and fast
• Retrofit old applications with shiny Web
interface
• Convert terminal apps to Web apps (screen
scraping?)
• Easily hack together Web admin apps using
proven command line tools
• Gluing together heterogeneous applications
(Web interface for ancient COBOL app?)
• More and more…

12. Conclusion
• CMS Webdash live demo (if any)
• Questions? Drop me an email:
Alex Tokarev <tokarev@cpan.org>