Annika Wagner

Ensuring Consistency of Conditional Graph Grammars - A Constructive Approach -

Abstract Consistency conditions describe basic properties of graphs as e.g. the existence or uniqueness of certain elements. A graph grammar is consistent if the start graph satisfies the consistency condition and the rules preserve this property. We propose a general construction that transforms global consistency conditions into preconditions for individual rules. A so-constructed rule is applicable to a consistent graph if and only if the derived graph is consistent, too. The relevance of this result is motivated by an example specification of a safety-critical system that is, a roundabout.

UML collaboration diagrams and their transformation to java

UML provides a variety of diagram types for specifying both the structure and the behavior of a system. During the development process, models specified by use of these diagram types have to be transformed into corresponding code. In the past, mainly class diagrams and state diagrams have been considered for an automatic code generation. In this paper, we focus on collaboration diagrams. As an important prerequisite for a consistent transformation into Java code, we first provide methodical guidelines on how to deploy collaboration diagrams to model functional behavior. This understanding yields a refined meta model and forms the base for the definition of a transformation algorithm. The automatically generated Java code fragments build a substantial part of the functionality and prevent the loss of important information during the transition from a model to its implementation.

Visualizing the synchronization of Java-threads with UML

Concurrent programming is a complex task, even with modern languages such as Java who provide language-based support for multithreading and synchronization. In addition to typical errors from sequential programming concurrent programming is prone to security and lifeness errors, which are difficult to detect due to the inherent nondeterminism in concurrent programs. While debugging is still mainly based on textual representations, we think that the use of visual languages can ease program comprehension. Once a synchronization error is detected, e.g. during testing, the error situation shall be visualized to analyze the reason for the error. With UML being a major visual modeling language for object oriented software development we decide to base our visualization on it and present how to visualize program traces with UML sequence and collaboration diagrams. We focus on the visualization of the synchronization of threads. For this purpose we extend UML to model the runtime mechanisms of the Java language constructs for synchronization.

DEFINING OPERATIONAL BEHAVIOR OF OBJECT SPECIFICATIONS BY ATTRIBUTED GRAPH TRANSFORMATIONS

A single pushout approach to the transformation of attributed partial graphs based on categories of partial algebras and partial morphisms is introduced. A sufficient condition for pushouts in these categories is presented. As the synchronization mechanism we use amalgamation of rules and show how synchronization can be minimized. We point out how the results obtained can be employed in order to define an operational semantics for object specification languages.

Ein Vorgehensmodell für die Multimedia-Entwicklung mit Autorensystemen

Zusammenfassung. Multimedia-Anwendungen sind interaktive Softwaresysteme und verlangen als solche, mit softwaretechnischen Methoden erstellt zu werden. Sie werden heutzutage in der Regel mit Hilfe von Autorensystemen entwickelt, die eine Ad-hoc-Entwicklung auf Implementierungsniveau unterstützen. Hierdurch und wegen des Fehlens etablierter Vorgehensmodelle für die Multimedia-Softwareentwicklung reduziert sich der Multimedia-Entwicklungsprozeß auf die Implementierungsphase. Dies führt zu den in der Softwaretechnik bekannten Problemen wie mangelnder Konzeption und fehlender Dokumentation. Wir stellen in diesem Beitrag ein Vorgehensmodell für die Entwicklung von Multimedia-Anwendungen vor, in dessen Mittelpunkt eine Analyse- und Entwurfsphase im Hinblick auf eine Implementierung der Multimedia-Anwendung mit einem Autorensystem stehen. Ausgehend von einem frameworkbasierten Analysemodell der Anwendung und einem Modell der Realisierungsmöglichkeiten mit einem konkreten Autorensystem wird systematisch ein Implementierungsmodell auf Instanzebene abgeleitet, das als Eingabe für das Autorensystem verwendet wird. Das postulierte Vorgehensmodell wird exemplarisch für das Autorensystem Director am Beispiel der Domäne multimedialer Lehr-/Lernanwendungen erläutert.Abstract. Multimedia applications are interactive software systems and should therefore be developed using software engineering techniques. They are nowadays built using authoring systems that support ad hoc implementation without a preceding modeling phase. Because of that and due to the lack of established process models for multimedia software development, the development process is reduced mainly to the implementation phase. This leads to problems well-known in software engineering like missing conceptualization and missing documentation. In this paper, we present a process model for the development of multimedia applications which is centered upon an analysis and a design phase with regard to an implementation with an authoring system. Starting from a framework-based analysis model of the application and a model of the programming capabilities of a concrete authoring system, an instance-level implementation model can be systematically derived. The proposed process model is exemplarily explained using the Director authoring system for the domain of computer-based training applications.

A Framework for Adding Packages to Graph Transformation Approaches

Graphs are a commonly used formalism for modeling many different kinds of static and dynamic data. In many applications, data modeling can be improved by using hierarchically structured graphs. But, while there already exist hierarchical graph data models, no general-purpose hierarchical graph data model exists yet, which unifies common features of these domain-specific models. In this paper, we present graph packages, a general formalism for defining hierarchical graphs, supporting the most important features found in known applications.

On the Expressive Power of Algebraic Graph Grammars with Application Conditions

In this paper we introduce positive, negative and conditional application conditions for the single and the double pushout approach to graph transformation. To give the reader some intuition how the formalism can be used for specification we consider consistency and an interesting representation for specific conditions, namely (conditional) equations. Using a graph grammar notion without nonterminal graphs, i.e. each derivation step leads to a graph of the generated language, we prove a hierarchy: graph grammars over rules with positive application conditions are as powerful as the ones over rules without any extra application condition. Introducing negative application conditions makes the formalism more powerful. Graph grammars over rules with conditional application conditions are on top of the hierarchy.