Business Logic Layer

The business logic layer [11] acts as an intermediary layer between the presentation layer (see Section ) and the data access layer (see Section ). All communication between these two layers has to be done via the business logic layer.

The business logic layer itself is again split into two parts. The first one is responsible for the handling of requests concerning users and their details. Firstly, it supplies a list of users that are available in the system. Secondly, it provides an interface to get additional information about a given user.

The second part of the business logic layer is responsible for supplying the functionality used to manage the tasks. It therefore offers several interfaces to achieve this goal. First, a list of all tasks or only a specific task in a simplified format is furnished. When a task is displayed in a simplified format, only the most important information is indicated to have a concise overview. Second, exhaustive data of all tasks or of a specific task may be requested. In this extended format, all information stored about a task is given. Third, the list of tasks, whether it is given in a simplified or complete form, may be limited to a given user. Fourth, a task may be added or updated. In order to achieve this, all data has to be given, that is the extended format has to be used. Last, a specific task may be removed from the list of tasks.

Note that all data passed to the business logic layer is supposed to be valid, validation of the user input is entirely let to the presentation layer (please refer to Section  for more details).

Due to the limits of the database used, the details to be stored as XML in the database have to be passed to the data access layer as a valid XML. Therefore, it is up to the business logic layer to compose the details indicated by the user to a valid XML file.