Alternative Web App Structures

From BarCamp DC Wiki

Presented at Bar Camp D.C., August 11, 2007

Presenter: Brock Wilcox

Applications reviewed:

Seaside: open source web application framework written in Smalltalk.

http://www.seaside.st/

Continutity: "a suite of libraries (not a framework) for building a highly structured web-based interface for your application, without using ad-hoc state management."

http://continuity.tlt42.org/

Notes from the presentation (originally from Matt Bowen's blog):

• Web App Structure
  • HTTP is stateless
    • Web application programs tend to be stateless
    • Normally, each new requests starts the app from scratch, then you try to get everything back from a session
• There's an alternative: continuations
  • Instead of the program running to output HTML, halt, start again with a new request (rinse, repeat) ...
  • You freeze the whole context (the state), and then the user does the next step, and the system picks right back up at the point where it left off
    • This is implemented through co-routines

• Seaside!
  • Written in SmallTalk
    • Uses squeak (an OS in a box, seriously isolated)
  • Application framework (think rails)
  • No templating system -- write your template in smalltalk
  • Offers through the web development

• Uncommon Web
  • Similar in concept to seaside
  • Use common lisp to handle continuations with a macro
  • Replay the source tree to a specific point

• Continuity
  • Do this stateful stuff in perl
  • Written by Brock Wilcox, our presenter
  • Uses co-routines
  • "Sorry perl's so ugly, but I love it so much."
  • Big problems with bookmarking. Oh well.