SES 46: Web Dynpro Controllers

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Today, let’s learn about Web Dynpro in SAP ABAP.

If a Web Dynpro component has access to another Web Dynpro component, then the parent component can declare the user of the child component. A Web Dynpro component interface has following parts:

  • Interface Controller: All components of Web Dynpro have 1 interface controller. And event handlers can be accessible to other components of Web Dynpro via methods, interface controller and data.
  • Interface Views: These depict visual interface of a component of Web Dynpro. The window and the interface view has one-to-one relationship, where every time a window is defined, a corresponding interface view is generate automatically. This makes accessing the window from outside the component.

A Web Dynpro application is the first point for a Web Dynpro component and can be addressed through a URL. If a Web Dynpro component has no views, there are no windows.

Points to remember before defining a Web Dynpro application:

  • Inbound plug behaves as entry point for nominated interface view.
  • The Web Dynpro component should be instantiated.
  • You should use the interface view of the root component which defines the default view assembly.

Component controller of a Web Dynpro acts as a component-wide controller. Usage declarations between controllers allow users the access of context data, methods of the declared controller and public attributes. A view controller of a Web Dynpro cannot be used as controller for others because then it disrupts the very concept of MVC paradigm.

Web Dynpro Entities

Custom controllers are the controllers defined by developer that are optional and are used to modularize component content. The customers controllers of a Web Dynpro allow users to reduce content of the controller.

When a particular component usage instance of a Web Dynpro is built, the parent component of the Web Dynpro has the ability of access the functions of the child component via its component interface controller.

Controller Types

Controller Types Description
View
Controller		Each view has layout and 1 view
controller; this one handles the
particular flow logic.
Component
Controller		A Web Dynpro component has only 1
component controller (global
controller), that’s visible to other
controllers. This controller drives
functionality of entire component.
Custom
Controller		These are optional and are defined at
design time, that are used to
encapsulate sub-functions of
component controller.
Window
Controller		A window has 1 window
controller that’s used to handle
data passed through inbound
plugs.
Configuration
Controller 		This one’s a custom controller
and may exist in any controller.

During runtime, all controller instances are singleton and it’s true for view controllers, since embedding of a view isn’t allowed in a view assembly. The lifetime of a controller in a Web Dynpro is not limited to time used to process programming and processing of user interface.

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