3.4.1.6 Querying of Quantities

The main purpose of the quantity server is to automatically generate lists of quantities which contain only those quantities which are needed by the particular models. When a model has to be evaluated the corresponding quantity list is supplied as parameter. Within the models quantities are accessed via handles which provide interface functions to query and store information in the quantities.

The quantity lists needed by the models are created once during the initialization phase. This approach has important advantages:

• The quantities a model need can be managed centrally.
• Thus dependencies of models can be drawn up.
• The developer of the models is restricted to the quantities registered for the model. Additional quantities have to be registered first. Due to this restriction uncontrolled use of quantities is prevented.