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In today’s emerging information systems, it is natural to have data distributed across multiple sites. We define a System of Databases (SyDb) as a collection of autonomous and heterogeneous databases. R-SyDb (System of Relational Databases) is a restricted form of SyDb, referring to a collection of relational databases, which are independent. Similarly, X-SyDb (System of XML Databases) refers to a collection of XML databases. Global integrity constraints ensure integrity and consistency of data spanning multiple databases. In this dissertation, we present (i) Constraint Checker, a general framework of a mobile agent based approach for checking global constraints on R-SyDb, and (ii) XConstraint Checker, a general framework for checking global XML constraints on X-SyDb. Furthermore, we formalize multiple efficient algorithms for varying semantic integrity constraints involving both arithmetic and aggregate predicates. The algorithms take as input an update statement, list of all global semantic integrity constraints with arithmetic predicates or aggregate predicates and outputs sub-constraints to be executed on remote sites. The algorithms are efficient since (i) constraint check is carried out at compile time, i.e. before executing update statement; hence we save time and resources by avoiding rollbacks, and (ii) the implementation exploits parallelism. We have also implemented a prototype of systems and algorithms for both R-SyDb and X-SyDb. We also present performance evaluations of the system.

Der Entwurfsprozess informationsverarbeitender Systeme ist gekennzeichnet durch die Beschreibung von speichernden, verarbeitenden und übertragenden Komponenten auf unterschiedlichen Abstraktionsstufen. Sowohl für spezifische Anwendungsdomänen als auch für die jeweiligen Abstraktionsstufen wurden in der Vergangenheit Werkzeuge entwickelt, die den Systemdesigner von der Phase der Anforderungsspezifikation bis hin zu Implementierung und funktionaler Erprobung begleiten. Beim Entwurf komplexer Systeme im allgemeinen und eingebetteter Systeme im besonderen stellt sich zusätzlich das Problem der Wiederverwendung von Komponenten aus früheren Entwürfen, der Transformation des Entwurfswissens über die Grenzen der Abstraktionsstufen hinweg sowie die Integration einer variablen Anzahl domänenspezifischer Werkzeuge in den Entwurfsprozess. Voraussetzung eines korrekten Designs ist dabei die anwendungsinvariante Integritätserhaltung aller beteiligten Entwurfsdaten unabhängig von ihrer Repräsentation. Nach der Diskussion des Integritätsbegriffs für konventionelle Informationssysteme und den nötigen Erweiterungen für eingebettete Systeme werden Verfahren zur Modellierung des Entwurfsprozesses vorgestellt, mit deren Hilfe eine der spezifischen Entwicklungsaufgabe optimal entsprechende Wissensbasis generiert und fortwährend neuen Anforderungen von Fremdwerkzeugen und Entwurfsverfahren angepasst werden kann. Sie erfordert vom Anwender keine Detailkenntnisse des zugrunde liegenden Datenmodells. Die Generierbarkeit der Wissensbasis und ihrer Werkzeuge beruht auf einem Metamodell, das sich auf eine erweiterbare Objektalgebra zur Struktur- und Verhaltensbeschreibung informationsverarbeitender Systeme stützt und in domänenspezifische Zielsysteme transformierbar ist. / The design process of data processing systems is characterized by the description of storing, processing and transmitting components on different levels of abstraction. In the past tools have been developed for specific application domains as well as for the respective abstraction levels. They support the system designer from the stage of the requirements specification down to implementation and functional test. During the sketch of complex systems in general and embedded systems in particular, problems occur in the following areas: reusing the components from former drafts; transforming the design knowledge across the boundaries of abstraction levels; integrating a variable number of domain specific tools in the design process. The precondition for a correct design is the integrity preservation of all involved draft data no matter which sources such as databases, XML files or conventional HOST file systems provide them. After discussing the integrity term regarding conventional information systems and the extensions necessary for embedded systems, approaches for modelling the design process are presented. They help to generate a knowledge base which is optimally adjusted to a particular design task and can be continuously adapted to new requests coming from external tools and design processes. The user does not need detailed knowledge about the knowledge base's underlying data model. The capability of generating the knowledge base and its tools is based on a meta model. First, this model is based on an extensible object algebra applied when describing the structure and behaviour of data processing systems and second, the model is transformable into domain specific target systems.

This thesis presents a new modelling method for information systems analysis and design, where the concept of service and the principles of service orientation are used for integrated modelling and reasoning about information systems architectures across organisational and technical systems boundaries. The concept of service enables cohesion of the intersubjective and objective modelling traditions by using a single type of diagram that facilitates detection of semantic inconsistency, incompleteness, ambiguity and discontinuity between the static and dynamic aspects of information systems specifications. The thesis is focused on three research topics, which are fundamental to the development of a new service-oriented modelling method. The first research topic concerns a pragmatic-driven specification of information systems. It clarifies answers to the research question: How can a conceptual modelling process be driven by pragmatic considerations? The second research topic provides a service-oriented modelling foundation for information systems analysis and design. It answers the research questions: How can the concept of service be used explicitly for the analysis and design of information systems and how can the static and dynamic aspects of information systems specifications be integrated at the conceptual level? The third research topic presents transition principles to implementation-specific design and answers the research question: How can service-oriented conceptual representations be aligned with implementation-specific design? The thesis contributes with a new knowledge to the area of conceptual modelling of information systems. The service-oriented modelling method consists of the modelling process, modelling language and techniques for the analysis and design of information systems on three levels of abstraction: pragmatic, semantic and syntactic. These three levels are necessary for a holistic understanding of enterprise architecture by stakeholders. The advantage of the service-oriented modelling method is that it can help to control traceability from information system design to original requirements. The method facilitates the semantic integration of the structural, behavioural and interactive aspects of information systems conceptual representations by using a single diagram type. The modelling language provides service-oriented constructs that are fundamental to building the major systems analysis patterns. The service-oriented modelling process contributes with seven steps of incremental design, which justifies various information systems components. The method provides the basis for a gradual and systematic way of modelling and an understanding of how pragmatic, semantic and logical information system requirements are linked together. The possibility to detect and eliminate undesirable characteristics of service-oriented diagrams can help to improve communication among stakeholders. Service-oriented specifications are computation-neutral and therefore they are more comprehensible for business analysis experts in comparison to implementation specific graphical representations of information systems. Finally, this thesis presents the challenges for future research, one of which is the development of the automated tools for the alignment of business models with implementation-specific information systems specifications.

Der Entwurfsprozess informationsverarbeitender Systeme ist gekennzeichnet durch die Beschreibung von speichernden, verarbeitenden und übertragenden Komponenten auf unterschiedlichen Abstraktionsstufen. Sowohl für spezifische Anwendungsdomänen als auch für die jeweiligen Abstraktionsstufen wurden in der Vergangenheit Werkzeuge entwickelt, die den Systemdesigner von der Phase der Anforderungsspezifikation bis hin zu Implementierung und funktionaler Erprobung begleiten. Beim Entwurf komplexer Systeme im allgemeinen und eingebetteter Systeme im besonderen stellt sich zusätzlich das Problem der Wiederverwendung von Komponenten aus früheren Entwürfen, der Transformation des Entwurfswissens über die Grenzen der Abstraktionsstufen hinweg sowie die Integration einer variablen Anzahl domänenspezifischer Werkzeuge in den Entwurfsprozess. Voraussetzung eines korrekten Designs ist dabei die anwendungsinvariante Integritätserhaltung aller beteiligten Entwurfsdaten unabhängig von ihrer Repräsentation. Nach der Diskussion des Integritätsbegriffs für konventionelle Informationssysteme und den nötigen Erweiterungen für eingebettete Systeme werden Verfahren zur Modellierung des Entwurfsprozesses vorgestellt, mit deren Hilfe eine der spezifischen Entwicklungsaufgabe optimal entsprechende Wissensbasis generiert und fortwährend neuen Anforderungen von Fremdwerkzeugen und Entwurfsverfahren angepasst werden kann. Sie erfordert vom Anwender keine Detailkenntnisse des zugrunde liegenden Datenmodells. Die Generierbarkeit der Wissensbasis und ihrer Werkzeuge beruht auf einem Metamodell, das sich auf eine erweiterbare Objektalgebra zur Struktur- und Verhaltensbeschreibung informationsverarbeitender Systeme stützt und in domänenspezifische Zielsysteme transformierbar ist. / The design process of data processing systems is characterized by the description of storing, processing and transmitting components on different levels of abstraction. In the past tools have been developed for specific application domains as well as for the respective abstraction levels. They support the system designer from the stage of the requirements specification down to implementation and functional test. During the sketch of complex systems in general and embedded systems in particular, problems occur in the following areas: reusing the components from former drafts; transforming the design knowledge across the boundaries of abstraction levels; integrating a variable number of domain specific tools in the design process. The precondition for a correct design is the integrity preservation of all involved draft data no matter which sources such as databases, XML files or conventional HOST file systems provide them. After discussing the integrity term regarding conventional information systems and the extensions necessary for embedded systems, approaches for modelling the design process are presented. They help to generate a knowledge base which is optimally adjusted to a particular design task and can be continuously adapted to new requests coming from external tools and design processes. The user does not need detailed knowledge about the knowledge base's underlying data model. The capability of generating the knowledge base and its tools is based on a meta model. First, this model is based on an extensible object algebra applied when describing the structure and behaviour of data processing systems and second, the model is transformable into domain specific target systems.