In modern object-oriented computer systems the internal state of the entire system consists of the internal states of many objects, probably distributed over a heterogeneous network of computers. The man machine interaction in such an application is based on the visualization of states on one hand and the modification of states in combination with event generation on the other hand. This paper describes concept and realization of a reusable service for general man machine communication.Keywords: graphical user interface, data visualization, service, object-oriented service OVERVIEWThis research arises from a cooperation with the IEEE task force on ECBS and has two main goals: First, to find a common standard for the process of creating large computer systems and second to define standards for reusable software components, the "services". A service is designed to solve a given problem by processing tasks and results. With a given communication platform it is possible to place the services on different hardware systems independent of the specification. This is realized by distributed objects for heterogeneous systems (Figure 1).Three basic types of services can be distinguished: The system services are needed for communication and process scheduling. The basic services are located above the system service. At this point of time, there are a layer for man machine interaction, for measurement and control and a database system for persistent data. The third type of service is application dependent, which means, that these services are build for a special solution, whereas the other ones only have to be configured for a given task.One of the most important services is the man machine interaction. The task of any man machine service (MMS) is to inform a human user of a system's state and to allow modifications of this state. Due to the fact that man can perceive and handle information fastest in a visual way, this is the best channel to inform about complex system states. The optical channel is also a good choice to support human interaction. This is achieved in feeding back the user's actions. A MMS has to provide two general functions:

In this approach, two basic services designed for the engineering of computer based systems (ECBS) are combined: a symbol-oriented man-machine-service and a high speed database-service. The man-machine service is used to build graphical user interfaces (GUI's) for the database service; these interfaces are stored using the database service. The idea is to create a GUI-builder and a GUI-manager for the database service based upon the man-machine service using the concept of symbols. With user-definable and predefined symbols, database contents can be visualized and manipulated in a very flexible and intuitive way. Using the gui-builder and gui-manager, a user can build and operate its own graphical user interface for a given database according to its needs without writing a single line of code.

This paper describes an approach for a platform-and implementation-independent design of user interfaces using the UIMS idea. It is a result of a detailed examination of object-oriented techniques for program specification and implementation. This analysis leads to a description of the requirements for man-machine interaction from the software-developers point of view. On the other hand, the final user of the whole system has a different view of this system. He needs metaphors of his own world to fulfill his tasks. It's the job of the user interface designer to bring these views together. The approach, described in this paper, helps bringing both kinds of developers together, using a well defined interface with minimal communication overhead.Keywords: graphical user interface, behavior model, dynamic model, interpreter, user interface management system OVERVIEWOne of the most important results in the separation of gui and application is the creation of two different working areas: The user interface designer and the application developer. Both of them have special skills and knowledges, the communication between them is done using a well defined interface. To reach this goal, firstly, a basic system for symbolization and manipulation of structured application defined information is used as a hardware independent platform. UIMS design normally leads to a large communication overhead between UIMS itself and the application: A more important point in the construction of such a system is to give the UIMS as much independence as possible. One of the best ways to solve this problem is to allow the man machine service to handle most parts of the dialogue control itself. For this reason, we have introduced two models in our system Fluids to define the user interface. 5 The static model describes the user interface structure, using the design and placement of their components. 6 The idea of symbolic information visualization is consequently used: Menus are aggregate symbols, composed of buttons, which are symbols too. Picture as the basic class is a container for a set of symbols without any internal relation. From this class are more specific classes derived: Menu, Mask, Table. Additional basic classes are not necessary, because classes with other semantic like Hierarchical Graphs can be constructed using the dynamic model. The complete static model is discussed other papers so that we put our focus on the dynamic or behavior model.