When working interactively on the computer, it is valuable to be able to undo a series of commands in order to return to a previous state. We identify contradictions and limitations in the basic concepts of undo. We examine the characteristics of undo, explain these limitations, and explore the requirements for more general recovery facilities.
The RESearch Queueing Package Modeling Environment (RESQME) is a system which provides an integrated, graphics-oriented, performance evaluation workstation environment for constructing, maintaining, revising and evaluating performance models of resource contention systems. In this paper we discuss examples illustrating its use and emphasize the iterative… (More)
The RESearch Queueing Package Modeling Environment (RESQME) is an interactive, graphics-oriented workstation environment for iteratively constructing, running and analyzing models of resource contention systems. It is built on top of the RESearch Queueing Package (RESQ) which provides the functionality to evaluate extended queueing networks. In this paper… (More)
Hierarchical performance modeling allows the modeler to create models either in a top-down process, where he or she creates a high-level model and progressively fills in the details replacing stubs with detailed submodels or in a bottom-up process, where he or she first builds a library of submodels (or uses an existing library of submodels) and then links… (More)
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… (More)
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… (More)
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… (More)
Many performance modeling systems are now graphically based, enabling the user to build a model by directly drawing and manipulating a pictorial model diagram on the computer display. These modeling systems generally provide a menu driven interface and an icon palette with which the user specifies the model by seleeting and I.inkkg icons and then providing… (More)