Contributions published at Database Technology (Michael Hanspeter Böhlen)

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When integrating data from autonomous sources, exact matches of data items that represent the same real world object often fail due to a lack of common keys. Yet in many cases structural information is available and can be used to match such data. As a running example we use residential address information. Addresses are hierarchical structures and are present in many databases. Often they are the best, if not only, relationship between autonomous data sources. Typically the matching has to be approximate since the representations in the sources differ.We propose pq-grams to approximately match hierarchical information from autonomous sources. We define the pq-gram distance between ordered labeled trees as an effective and efficient approximation of the well-known tree edit distance. We analyze the properties of the pq-gram distance and compare it with the edit distance and alternative approximations. Experiments with synthetic and real world data confirm the analytic results and the scalability of our approach.

This book constitutes the refereed proceedings of the International Conference on E-Government, TCGOV 2005, held in Bolzano, Italy in March 2005. The 28 revised full papers presented were carefully reviewed and selected from 92 submissions. The papers are organized in topical sections on e-democracy: improving citizen participation and policy making, e-democracy: experiences from different countires, political and societal implications, security for e-government services, semantic Web technologies, architectures for government application integration, case studies for government application integration, decision support systems, managerial and financial aspects of e-government projects, and e-procurement.

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In data integration, autonomy of data sources is usually given higher priority than diversity of information needs of data end-users. However, data receivers strongly differ in their information needs and in their conceptual mental models of their particular application area. In this paper, we review existing data integrations approaches for their compliance with the ASME criteria (Abstraction, Selection, Modeling, and Explicit semantics). Our goal is to assess whether existing data integration approaches provide suitable means for truly user-specific data integration from selected data sources. In particular, we investigate whether data from heterogeneous sources can be integrated in a way that it perfectly fits to a particular user's information needs, emphasizing his individual way to perceive a domain of interest. Additionally, we survey data integration approaches for their support for explicit representation of data semantics and for shielding users from technical-level heterogeneities of underlying data sources.

Effective collaborate business process support is essential in today’s business. In this paper, we address this aspect within documents. Often, such text documents are stored unsystematically in a rather confusing file structure with an inscrutable hierarchy and little access control. Business data, on the other hand, are stored in a systematic way in databases allowing multi-user, multi-site, user-/role-specific controlled access. We store text documents in databases and exploit these database capabilities: collaborative business processes then can be defined per document or any part of a document. In this paper, we present this dynamic collaborative business process concept and the prototype within documents for our database-based collaborative editor. We evaluate the potential of such business processes for the quality of communication and documentation.

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Markets and as a consequence requirements on enterprises have changed in the past years. Nowadays companies have to deal with global markets, shorter product-lifecycles as well as the need for more customer-orientation. The increased dynamics of innovation together with the proliferation of knowledge force enterprises to concentrate on their core competencies and consider outsourcing of further activities. The functional construction of cooperative inter-organizational networks has become a factor for the success of an enterprise – especially for smaller and medium sized enterprises.Inter-organizational cooperation offers the possibility to join organizational knowledge and abilities of the involved parties, to expand both their business areas and their market access. These cooperative networks enable enterprises tp merge efforts and distribute their products not only faster but also further and establish higher trade barriers for competitors. Several new cooperative forms have been developed to allow the necessary amount of flexibility (e.g. virtual organizations, communities of practice).Distributed collaborations are often not possible without the use of information and communication technologies (ICT). To gain an efficient cooperation ICT have to be adjusted to the special requirements of the particular inter-organizational cooperation. In order to allow a systematic elicitation of the ICT requirements resulting the specific organizational structure of an inter-organizational cooperation, a classification frame for inter-organizational network organizations is developed in this thesis. Based on the identified classification criteria, generic ICT functionalities for the support of the business partners are specified.During the cooperation process the way of collaboration and the relationship between the partners may change. It is necessary to know the single stages of the cooperation to determine the particular needs of the participants for information and coordination. Thus, one goal of this work is to define a common model of the inter-organizational cooperation process and the main phases within this process. Identified tasks and responsibilities during the determined phases offer a better understanding of the needs of cooperative environments. Based on the obtained results, overall requirements on ICT for inter-organizational cooperations are determined.Finally both the structural-organizational as well as the process aspects of the requirements elicitation are combined and specific components of an IS architecture are determined to offer a general support of cooperative network organizations. This work is focusing mainly on three components the translator, the coordinator and the evaluator.Enterprises offer their services at the platform in form of service descriptions. However, there are several industrial service description standards like ebXML, RosettaNet, XPDL available that can be applied for this purpose. Although these standards capture similar concepts, they nonetheless rely on diverging interpretations of processes and their components. In order to allow enterprises a standard-independent access to the platform to publish their services as well as search for service partners, the platform encloses a translator component. This translator offers a semantical correct translation between two or more service description standards based on the semantical similarities between them. The semantical similarities can be determined automatically by using formal ontologies. Once the semantical similarities are detected a translations structure between two standards is build. This translation structure contains the necessary information to translate a service-based document from one standard to another. The translation implemented by the translation component offers a complete mapping of the information contained in the source document to the target standard. Still, the generated target document is correct with respect to the target standard specification. Using the translation component the heterogeneity between service offer and request can resolved and thus, the service selection as well as the service enactment can be supported.The coordination component implements a service-based, mediator-oriented coupling of the internal processes of the enterprises participating in the cooperation. Several interaction protocols are developed in order to support the interaction between business partners during the cooperative service enactment. Using standardized e-service technologies, enterprises can combine their services without time-consuming and expensive adaptation of their internal IS.To save the experiences that have been derived in the evaluation step of the termination phase, the platform offers an evaluation component. The evaluation component allows the explicit description of the reputation of an enterprise in form of a cultural independent rating and thus, can be used especially for supporting distributed cooperations. The evaluation itself is supported with a standardized questionnaire. Based on given criteria, enterprises can be categorized, which offers a more fine-grained search of partners within the network platform.For the specification of the components of the network platform use cases, scenarios, interface prototypes, code fragments as well as class models are specified. These models provide an implementation-focused description of the platform's functionality that can be used as an base for an implementation of the platform.

In database federations the integrity problem arises from the degree of heterogeneity and autonomy of participating component database systems. This causes integrity control more complicate than that in traditional centralized database systems. Semantic integrity should be considered in two phases: constraint federation and constraint enforcement. Otherwise, the administrators of component database systems might not agree to join the federation, or some or even all of component databases will be in an inconsistent state when an update is executed. The semantic integrity of federated database refers to representation integrity and enforcement integrity. The representation integrity means that the constraint definition of federated database schema should correctly reflect the characteristics of schema integration. The enforcement integrity means that the federated database state should be consistent with constraints defined over it, when an update is executed. In this thesis, we propose a new component to keep the semantic integrity of federated database. Firstly, we specify an integrity control component, which plays an extendible part of an FDBMS. A set of modules within a reference architecture is given; different degrees of evaluation autonomy are distinguished; and coupling principle is developed to unravel conflicts between the evaluation state of component constraints and that of global ones. Secondly, we develop integrity control enforcement policies for the federation policy. We show that this model is adaptable and flexible to represent the characteristics of federation and the application requirements of constraint enforcement plan. Thirdly, we define an integrity constraint type model that acts as a canonical model. It represents component constraints as integrity constraint types. Based on this model, federation users can translate component constraints, then integrate them and form global ones. These two models, taken together, preserve the representation integrity at the constraint federation phase. Fourthly, we give a two-step approach to enforce constraints. This approach is made up of two parts: type-based two-phase evaluation and policy-based two-phase commitment. It maintains the enforcement integrity at the constraint enforcement phase. Finally, the feasibility of the proposed component is implemented in a prototype, called MIGI. Spatial constraint federation and spatial constraint enforcement have been taken into account in MIGI.

This thesis presents a methodology extension named MeTHOOD (Measures, Transformation Rules and Heuristics for Object-Oriented Design) that supports the design of objectbases. MeTHOOD integrates measures describing the design objectives, heuristics showing design alternatives and transformation rules that enable design transformations. MeTHOOD makes design knowledge for conceptual objectbase schemas (conceptual object-oriented class schemas) more tangible. Although a large amount of this important knowledge is available in the literature, it is hardly usable for designers because it is very scattered, on different levels of abstraction and not integrated. Thus, the objective of this thesis is to enable a design process for efficient and continuous quality inspection and improvement of conceptual class schemas by efficiently providing design knowledge. The core of MeTHOOD is a catalogue of integrated design knowledge consisting of already existing as well as new object-oriented design heuristics, transformation rules and measures. This knowledge is the base for the iterative MeTHOOD design process. It consists of the main activities measurement, design inspection and design transformation. Using measurement, important properties of the schema are assessed. Based on the measured values and the heuristics, it is possible to inspect the schema systematically. The result of the inspection is a set of potential design flaws. The actual design flaws (identified by the designer) can then be eliminated using schema transformation. The result is a new schema that can be compared to the old one using new and old measures. These activities are supported by concrete measures and heuristics acting as a driver for transformations. The process is supported by a design support system called MEx (MeTHOOD Expert). MEx provides semi-automatic design monitoring, heuristic checking and design transformation using the design knowledge of the MeTHOOD catalogue.

During the past decade a new class of systems has emerged, which plays an important role in the support of efficient business process implementation: workflow systems. Despite their proliferation however, workflow systems are still being developed in an ad hoc way without making use of advanced software engineering technologies such as component-based system development and reuse of architecture artifacts.This work proposes a modern approach to workflow system construction. The approach is centered around a domain-specific software architecture metamodel (the REWORK metamodel) and a repository-based composition framework for workflow system construction out of reusable reactive components. The architecture metamodel defines the component and connector abstractions necessary for describing the static and dynamic aspects of a workflow system. The composition framework defines the lifecycle of a workflow system and supports the dynamic extension of a kernel workflow management system with application-specific elements. Appropriately, resulting systems are called REWORK systems.An event- and repository-based style underlies the REWORK framework. Events are the only component integration mechanism used in REWORK systems. Repositories support both system development by storing artifacts which are used for workflow system development and system operation by making explicit the structure of a running REWORK system.The iterative workflow system composition lifecycle proposed in this thesis comprises the following phases: the architecture analysis phase allows the identification and characterization of processing entities which participate in workflow execution; this phase is supported by a classification framework for processing entities in accordance to their integration-related properties. During the architecture definition phase workflow system components are defined and their behavior is tailored to specifications of workflows which are intended to be executed by the resulting system; furthermore, organizational relations and task assignment policies for these components are declaratively defined. The implementation phase is largely automated and consists in the instantiation of the defined components on top of an event-based operational infrastructure.As already mentioned the entire lifecycle is supported by repositories which store the workflow system artifacts. The iterative development comes into the picture once existing workflow systems have to be maintained either by adding new repository artifacts or by modifying existing ones. Thus, we dedicate a part of this thesis to the description of these repositories.