An application library is a generic method with the help of which a server application makes data and functions available to other client applications.
The generic character of an application library is that the requesting client application determines which specific functions of the server application to which the library belongs are accessible using the application library. It does this using a standardized function call. Subsequently it is in the program responsibility of the client application to use the available functions of the library in suitable places. For example, in the Web Survey this happens in that when selecting suitable library functions to read and write data, only those functions are offered whose signatures are suited to the respective task.
Application libraries are used for the following purposes in the Web Survey:
The following graphic shows how the Web Survey can use an application library to transfer data from a server application that is set up in the same or in another system:
In the first step the client application (here: Web Survey) determines the functions that will be made available by the application library. For example, the graphic shows a function to create a target group hierarchy and a function to generate default values in the questionnaire. The call of these functions from the perspective of the Web Survey leads to other application-specific functions being executed within the application library that access the data of the server application and prepare this in a suitable form. The graphic presents as an example the case that the data available in the server application on the organizational structure in the Web Survey is used to create a target group hierarchy. In addition, master data tables of the server application are read and the data determined in this way is used to generate default values for input fields in the questionnaire.
The three areas presented in the graphic (Web Survey, application library, and server application) can also occur several times within a scenario:
The concept of the application library is to set up an integration layer between two applications. An application library is not part of the Web Survey instead from the view of a server application it makes the possibility available that any client applications, which use the interface of an application library, can communicate with the server application.
The following applications already contain an application library that you can use in the Web Survey: