• Design patterns and MVC
• MVC frameworks
• Catalyst features
• Catalyst demo
• Additional resources

• Originally a concept in architectural design: A "pattern" was a template for solving a particular type of design problem.
• "Borrowed" by Kent Beck and Ward Cunningham and applied to software design -- eventually Beck and Cunningham's work led to the first wiki, the Portland Pattern Repository (a/k/a "Ward's wiki").
• The definitive work in this area is Design Patterns, a/k/a "the Gang of Four book"
  
• Design patterns provide a set of reusable solutions to commonly occurring problems of software design.
• They also provide the basis for a shared vocabulary to discuss these problems.

• MVC == Model-View-Controller
• Originated in Smalltalk
• Can describe any sort of user-input-driven application, but is most frequently used to describe GUI applications. More recently, is usually applied to web application development problems.
• Model = Object(s) representing the data layer of the application
• View = The representation of the model state displayed back to the user
• Controller = The facilities for querying and changing the state of the data (possibly as a result of user input or action)

• The biggest advantage: In an MVC application with proper encapsulation, the three layers are largely decoupled.
• This means you can change the appearance of the application without redesigning the data model, or change the underlying RDBMS from SQLite to Oracle without changing any of the code in the CGI layer.
• This also means you can have different people/teams working on the different layers without them getting in each others' way -- as long as the interfaces between the layers are well defined.

• Ruby on Rails
• Django
• TurboGears
• Cocoon
• Struts
• Maypole
• Jifty
• Catalyst

• $TIMTOWTDI++: Extremely flexible plugin-based architecture
• Model- and view-agnostic: support for all popular alternatives, or roll your own
  
• Supports multiple (independent) models, views, and controllers
• Built-in web server for rapid application development and debugging
• Flexible access and error logging
• Support for auto-generation of scaffold code for all components.
• Modular authentication/authorization framework
• Deploy into production with built-in server, CGI, FastCGI, or mod_perl versions -- all auto-generated, and all using same codebase to run.

(Catalyst flow diagram lifted from Catalyst wiki.)

• For some reason, it's traditional to develop a wiki as a demo -- don't ask me why; it's just what you do.
• This demo was adapted from a Perl.com article on Catalyst -- with some modifications.

• Perl.com article
• Main catalyst site
• Catalyst wiki
• Catalyst blog
• #catalyst on freenode
• catalyst mailing list