Data Retrieval 

This section provides an overview of data retrieval in a Web Dynpro application. One of the main concepts of Web Dynpro technology is the Model View Controller (MVC) principle, and its approach is followed here. The MVC principle features a clear separation of the user interface, application logic, data retrieval, and data flow. Information about the MVC concept is available under Concepts.

You can use various different data sources for your Web Dynpro application. The Web Dynpro model is the entity that forms the interface with an existing back end or a local data source. For a simple connection to the back end, wizards are available that generate the relevant classes for your application. For information on how to define such a back end interface, refer to the sections on importing the different model types, such as Importing a Web Service Model.

You can define several models for each application. In a model declaration you define which model is to be the valid interface at runtime. With this reference, the application entity Web Dynpro component is addressed. More information is available under Referencing a Model.

The controllers are responsible for the data flow between the model and the other Web Dynpro entities. The data transport between the model and the controller is referred to as model binding – that is, there is a reference to the back-end data in the Web Dynpro application.