Sonderforschungsbereich 501
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- SDL (2)
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- building automation (2)
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- reuse (2)
- temporal logic (2)
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Faculty / Organisational entity
1998,4
In order to improve the quality of software systems and to set up a more effective process for their development, many attempts have been made in the field of software engineering. Reuse of existing knowledge is seen as a promising way to solve the outstanding problems in this field. In previous work we have integrated the design pattern concept with the formal design language SDL, resulting in a certain kind of pattern formalization. For the domain of communication systems we have also developed a pool of SDL patterns with an accompanying process model for pattern application. In this paper we present an extension that combines the SDL pattern approach with the experience base concept. This extension supports a systematic method for empirical evaluation and continuous improvement of the SDL pattern approach. Thereby the experience base serves as a repository necessary for effective reuse of the captured knowledge. A comprehensive usage scenario is described which shows the advantages of the combined approach. To demonstrate its feasibility, first results of a research case study are given.
1998,7
The notion of formal description techniques for timed systems (T-FDTs) has been introduced in [EDK98a] to provide a unifying framework for description techniques that are formal and that allow to describe the ongoing behavior of systems. In this paper we show that three well known temporal logics, MTL, MTL-R , and CTL*, can be embedded in this framework. Moreover, we provide evidence that a large number of dioeerent kinds of temporal logics can be considered as T-FDTs.
1996,15
A non-trivial real-time requirement obeying a pattern that can be foundin various instantiations in the application domain building automation, and which is therefore called generic, is investigated in detail. Starting point is a description of a real-time problem in natural language augmented by a diagram, in a style often found in requirements documents. Step by step, this description is made more precise and finally transformed into a surprisingly concise formal specification, written in real-time temporal logic with customized operators. Wereason why this formal specification precisely captures the original description- as far as this is feasible due to the lack of precision of natural language.
1997,2
This paper discusses the benefits and drawbacks of caching and replication strategies in the WWW with respect to the Internet infrastructure. Bandwidth consumption, latency, and overall error rates are considered to be most important from a network point of view. The dependencies of these values with input parameters like degree of replication, document popularity, actual cache hit rates, and error rates are highlighted. In order to determine the influence of different caching and replication strategies on the behavior of a single proxy server with respect to these values, trace-based simulations are used. Since the overall effects of such strate- gies can hardly be decided with this approach alone, a mathematical model has been developed to deal with their influence on the network as a whole. Together, this two-tiered approach permits us to propose quantita- tive assessments on the influence different caching and replication proposals (are going to) have on the Inter- net infrastructure.
1996,19
Due to the large variety of modern applications and evolving network technologies, a small number of general-purpose protocol stacks will no longer be sufficient. Rather, customization of communication protocols will play a major role. In this paper, we present an approach that has the potential to substantially reduce the effort for designing customized protocols. Our approach is based on the concept of design patterns, which is well-established in object oriented software development. We specialize this concept to communication protocols, and - in addition - use formal description techniques (FDTs) to specify protocol design patterns as well as rules for their instantiation and composition. The FDTs of our choice are SDL-92 and MSCs, which offer suitable language support. We propose an SDL pattern description template and relate pattern-based configuring of communication protocols to existing SDL methodologies. Particular SDL patterns and the configuring of a customized resource reservation protocol are presented in detail.
1996,9
Ziel dieser Arbeit ist es, eine Methode zur Verfügung zu stellen, mit der ein Simulator für gebäudespezifische Aufgaben modelliert werden kann. Die Modellierung muß dabei so angelegt sein, daß sowohl einfache als auch sehr komplexe Simulatoren für spezielle Gebäude entworfen werden können. Aus dem erstellten Modell ist es anschließend möglich, mit Hilfe von Generatoren automatisch ein Programm zu erzeugen. Dadurch kann ein Entwerfer ohne spezielle Kenntnisse auf dem Gebiet der Simulation einen Gebäude-Simulator entwickeln. Zur Modellierung wurde ein domänenspezifischer Katalog von Entwurfsmustern erstellt. Dabei können die einzelnen Muster direkt zur Modellierung und Codegenerierung eingesetzt werden.
1996,14
The purpose of this expose is to explain the generic design of a customized communication subsystem. The expose addresses both functional and non-functional aspects. Starting point is a real-time requirement from the application area building automation. We show how this application requirement and some background information about the application area lead to a system architecture, a communication service, a protocol architecture and to the selection, adaptation, and composition of protocol functionalities. The reader will probably be surprised how much effort is necessary in order to implement the innocuous, innocent, inconspicuous looking application requirement. Formal description techniques (FDTs) will be used in all design phases.
1997,1
A generic approach to the formal specification of system requirements is presented. It is based on a pool of requirement patterns, which are related to design patterns well-known in object-oriented software development. The application of such patterns enhances the reusability and genericity as well as the intelligibility of the formal requirement specification. The approach is instantiated by a tailored real-time temporal logic and by selecting building automation systems as application domain. With respect to this domain, the pattern discovery and reuse tasks are explained and illustrated, and a set of typical requirement patterns is presented. Finally, the results of a case study where the approach has been applied are summarized.
1996,6
Representations of activities dealing with the development or maintenance of software are called software process models. Process models allow for communication, reasoning, guidance, improvement, and automation. Two approaches for building, instantiating, and managing processes, namely CoMo-Kit and MVP-E, are combined to build a more powerful one. CoMo-Kit is based on AI/KE technology; it was developed for supporting complex design processes and is not specialized to software development processes. MVP-E is a process-sensitive software engineering environment for modeling and analyzing software development processes, and guides software developers. Additionally, it provides services to establish and run measurement programmes in software organizations. Because both approaches were developed completely independently major integration efforts are to be made to combine their both advantages. This paper concentrates on the resulting language concepts and their operationalization necessary for building automated process support.
1998,3
Die systematische Verbesserung von Techniken zur Entwicklung und Betreuung von Software setzt eine explizite Darstellung der in einem Projekt ablaufenden Vorgnge (Prozesse) voraus. Diese Darstellungen (Prozemodelle) werden durch Software- Prozemodellierung gewonnen. Eine Sprache zur Beschreibung solcher Modelle ist MVP-L. Verschiedene Standard-Prozemodelle existieren bereits. Bisher gibt es jedoch kaum dokumentierte Software-Entwicklungsprozesse, die speziell fr die Entwicklung reaktiver Systeme entworfen worden sind, d. h. auf die besonderen Anfordernisse bei der Entwicklung reaktiver Systeme zugeschnitten sind. Auch ist bisher nur wenig Erfahrung dokumentiert, fr welche Art von Projektkontexten diese Prozesse gltig sind. Eine Software- Entwicklungsmethode, die - mit Einschrnkungen - zur Entwicklung reaktiver Systeme geeignet ist, ist SOMT (SDL-oriented Object Modeling Technique). Dieser Bericht beschreibt die erfahrungsbasierte Modellierung der Software-Entwicklungsprozesse von SOMT mit MVP-L. Zunchst werden inhaltliche Grundlagen der Software-Entwicklungsmethode SOMT beschrieben. Insbesondere wird auf die eingesetzten Techniken und deren Kombination eingegangen. Anschlieend werden mgliche Projektkontexte charakterisiert, in denen das SOMT-Modell im Sinne eines Erfahrungselements Gltigkeit hat. Darauf werden der Modellierungsvorgang sowie hierbei gemachte Erfahrungen dokumentiert. Eine vollstndige Darstellung des Modells in grafischer MVP-L-Notation befindet sich im Anhang. Die Darstellung des Modells in textueller Notation kann der SFB-Erfahrungsdatenbank entnommen werden.