1830823
Playing with time: on the specification and execution of time-enriched LSCs
We extend live sequence charts (LSCs), a highly expressive variant of sequence diagrams, with timing constructs, thus making the language suitable for specifying the behavioral requirements of time-intensive systems. We follow R. Alur and T.A. Henzinger (see Software Tools for Technology Transfer, vol.1, p.86-109, 1997) in basing the extension on a single clock object. We have implemented the extension in full in our play-engine tool, which provides user-friendly ways to play in the timing constraints, together with a powerful mechanism that can execute, or play out, the time-enriched requirements directly, without the need for an intra-object system model. It seems that in addition to many advantages in testing and requirements engineering, for some kinds of systems this could lead to the requirements actually serving as the final implementation.
62551817
A Fast Multi-Scale Method for Drawing Large Graphs
8837470
Reactive Animation
Software engineers use system visualization mainly in two domains: algorithm visualization and system visualization, and both of these are often animated. In this paper we provide a generic link between the specification and animation of complex object-oriented reactive systems, which constitute one of the most important and difficult classes of systems. The link and its methodology form a basis for communication between standard reactive specification tools and standard animation tools. Reactive Animation can be used in a wide range of applications: computer games, navigation and traffic systems, interactive scientific visualization. Reactive Animation helps make the programming of such applications more reliable, expeditious and natural to observe and comprehend. We illustrate two examples: a complex biological model of thymic T-cell behavior and a traffic simulation. 3
13956705
Drawing Directed Graphs Using One-Dimensional Optimization
We present an algorithm for drawing directed graphs, which is based on rapidly solving a unique one-dimensional optimization problem for each of the axes. The algorithm results in a clear description of the hierarchy structure of the graph. Nodes are not restricted to lie on fixed horizontal layers, resulting in layouts that convey the symmetries of the graph very naturally. The algorithm can be applied without change to cyclic or acyclic digraphs, and even to graphs containing both directed and undirected edges. We also derive a hierarchy index from the input digraph, which quantitatively measures its amount of hierarchy.
7233048
Multiple instances and symbolic variables in executable sequence charts
We extend live sequence charts (LSCs), a highly expressive variant of sequence diagrams, and provide the extension with an executable semantics. The extension involves support for instances that can bind to multiple objects and symbolic variables that can bind to arbitrary values. The result is a powerful executable language for expressing behavioral requirements on the level of inter-object interaction. The extension is implemented in full in our play-engine tool, with which one can execute the requirements directly without the need to build or synthesize an intra-object system model. It seems that in addition to many advantages in testing and requirements engineering, for some kinds of systems this could lead to the requirements actually serving as the final implementation.
2779311
The immune system as a reactive system: modeling T cell activation with statecharts
The construction of reliable reactive systems is considered to be one of the most challenging goals in the fields of software and system engineering. The definition of a reactive system suits biological systems at different levels, ranging from gene networks, developing embryos and the immune system. We report here the application of a tool developed for constructing computerized systems to the modeling and analysis of a biological system, the immune system. We use the language of statecharts within the framework of object-oriented modeling. The results described here indicate that this modeling strategy can contribute to the transition of biology from the phase of analysis to the phase of synthesis.
7099239
Statecharts in the making: a personal account
How avionics work led to a graphical language for reactive systems where the diagrams themselves define the system's behavior.