Helma NG

Jetzt fängt wieder alles von vorne an

Hannes Wallnöfer

Some Facts about Helma 1

• In development since late 1990s
  • CVS started December 2000
  • Changelog starts January 2001
• Started with FESI EcmaScript interpreter
  • Replaced with Rhino in Helma 1.3 (summer 2003)
• ca. 50.000 LOC
  • 14.000 LOC for DB layer
  • 11.000 LOC for application framework
  • 8.000 LOC for scripting layer
  • Diseconomies of scale
  • COCOMO estimate: 12 person-years

The slow arrival of Helma 2

• Announeced as early as 2003
• Fueled by the feeling that something smells wrong
  • Everything is in Java and feels rigid
  • Things are more complex than they need to be
  • Application structure is idiosyncratic

Scopes in Helma 1 ...

... and in Helma NG

Helma NG basics

• global functions:
  • importModule(), importModuleAs(), importFromModule()
  • getResource()
  • parseSkin()
• modules can be shared, by default they're not
  • __shared__ = true;
• compiled scripts are cached, scopes are not
  • ...except for the shared ones

Helma NG modules: simpleweb and skin

• Mimic Helma 1 web framework
• ...but not really strictly
• Web modules are like apps in apps
• Skins can extend other skins

Helma NG modules: minibase

• Mimics Django style persistence
• Storable interface
• Storage imlementation

Helma NG shell