The following documentation describes the BSP programming model:
BSP Applications
BSPs
BSP Directives
Central Classes and Interfaces
Important Global Objects
BSP Extensions
Model View Controller (MVC)
Stateful and Stateless
Control Flow and Lifetime
Caching
Page Design
Accessibility
For SAP Web AS 6.20, the BSP programming model was enhanced with the MVC design pattern as well as the paradigm of the BSP extensions.