Robert F. Gordon

Concepts and implications of undo for interactive recovery

Software, ranging from editor/formatters to spreadsheet packages to integrated decision support systems, provides the capability to create, revise and destroy documents interactively on the computer. The user can issue one command that will change objects throughout the document, delete objects, insert new objects, or rearrange existing objects. After making a change, the user may find that he or she made an error or prefers a prior version. It is valuable then to be able to undo a series of commands and to return to a previous state of the document. Whereas earlier systems required the user to have saved the prior state to accomplish this, interactive systems are now beginning to provide some form of undo capability. With a recovery mechanism, the user can remove the effects of mistakenly-issued commands, and has

The Research Queueing Package Modeling Environment (resqme)

The Research Queueing Package Modeling Environment (RESQME) provides a graphical environment for constructing, solving, and analyzing the results of extended queueing network models of resource contention systems. It has been used to improve the performance of existing and planned systems in such application areas as computer Systems, communications networks, manufacturing processes, transportation systems, customer service facilities. RESQME provides the capability to specify a queueing model by drawing a network diagram and attaching attribute information to each object in the diagram. It then evaluates the model using its general-purpose, discrete event simulation software and produces graphical and tabular performance results, along with animation on the original model diagram. Confidence interval methods are incorporated to insure that the results of a simulation meet the desired level of accuracy.

Animating Simulations In RESQME

The RESearch Queueing Package Modeling Environment, RESQME, is a graphical environment for creating and modifying queueing models and for evaluating and analyzing the results. An animation facility is a natural adjunct to the graphics-oriented capabilities of this system. In such an environment, animation provides a powerful tool for effectively visualizing massive amounts of information. This makes it easier for the modeler to relate events in the model with processing in the real-world system. Animation enhances the modelers ability to debug the model, to understand the model interactions and the impact of model changes, and to communicate the results to others. In this paper, we describe the animation facility in RESQME.

End-user object-oriented programming by means of an object-oriented interface

An object-oriented interface (OOI) provides the capability of object-oriented programming to the end-user (non-programmer). In this paper, we provide an example of an OOI for the specific application area of simulation modeling. We describe how this OOI provides the end-user with the requisite tools for object-oriented programming in this domain. The end-user programs, compiles, runs, and analyzes the results of simulation models by using the objects and functions provided by the interface. We stipulate that the features associated with object-oriented programming (ie., instantiation, information hiding, inheritance, polymorphism, abstract data types, message-passing, and extensibility) are provided to the end-user by this interface and that they are the very features that make the resulting package powerful and easy to use.

An architecture for integrating logical and physical animations for general-purpose graphical simulation systems

Animation of the logical model is important for debugging the model, and animation of the physical system is important for communicating the results to others. To assure accuracy and consistency between these two animation views of the system, it is necessary to integrate the model building with the production of each animation. This paper describes a new architecture for developing simulation models so that the model created can be used to display both the animation of the system logic and the animation of the physical system.