Architecture and use of D2M2, the Delft Direct Manipulation Manager

A user interface management system is presented based on an object-oriented approach to the design of both the user interface and the application semantics. The data for user interface and application semantics are stored and processed apart. However, the modelling technique is identical for both, using the same tool for semantic data modelling. The modelling technique supports most characteristics of the object-oriented paradigm: objects, classes and inheritance. The diagrams used can describe amongst others the concepts of classification, aggregation, decomposition, generalization, specialization and role attributes. Attributes of objects can be described in property forms. Transition diagrams, including pre— and post-conditions, are applied to specify the interaction possible to the end user. The concepts supported by this tool are described and discussed. This tool as well as the products it can produce are based on a graphical user interface. From these specifications a run time version of the application can be generated. A protocol is used for the communication between application and user interface manager during run time. The features of Delft Direct Manipulation Manager are demonstrated with the design and implementation of a small application with direct manipulation.