Rainer Unland

On the semantics of complex events in active database management systems

Active database management systems have been developed for applications needing an automatic reaction in response to certain events. Events can be simple in nature or complex. Complex events rely on simpler ones and are usually specified with the help of operators of an event algebra. There are quite a few papers dealing with extensions of existing event algebras. However, a systematic and comprehensive analysis of the semantics of complex events is still lacking. As a consequence most proposals suffer from different kinds of peculiarities. Independent aspects are not treated independently, leading to shady mixtures of aspects in operators. Moreover, aspects are not always treated uniformly. Operators may have other semantics than expected. The paper addresses these problems by an extensive and in-depth analysis of the foundations of complex events. As a result of this analysis, a (formal) meta-model for event algebras is introduced that subdivides the semantics of complex events into elementary, independent dimensions. Each of these dimensions are discussed in detail. The resulting language specification fulfils the criteria for a good language design (like orthogonality, symmetry, homogeneity, lean set of language constructs) to a large extent.

A concise introduction to autonomic computing

1. IntroductionThe advances in computing and communication tech-nologies and software have resulted in an explosive growthin computing systems and applications that impact allaspects of our life. However, as the scale and complexity ofthese systems and applications grow, their development,configuration and management challenges are beginning tobreak current paradigms, overwhelm the capabilities ofexisting tools and methodologies, and rapidly render thesystems and applications brittle, unmanageable andinsecure.This has led researchers to consider alternativeapproaches based on strategies used by biological systemsto successfully deal with similar challenges of complexity,dynamism, heterogeneity and uncertainty. Autonomiccomputing is emerging as a significant new strategic andholistic approach to the design of complex distributedcomputer systems. It is inspired by the functioning of thehuman nervous system and is aimed at designing andbuilding systems that are self-managing. Morespecifically, an autonomic system is a self-managing,autonomous and ubiquitous computing environment thatcompletely hides its complexity, thus providing the userwith an interface that exactly meets her/his needs. Thesystem will always decide on its own, using high-levelguidance from humans, what needs to be done to keep itstable. It will constantly check and optimize its status,and automatically adapt itself to changing conditions.Self-management is achieved through key aspects such asself-governing, self-adaptation, self-organization, self-optimization, self-configuration, self-diagnosis of faults,self-protection, self-healing, self-recovery, and autonomy.Achieving these goals come down to bringing pre-emptiveand proactive approaches to all areas of a computingsystem. Meeting these challenges of autonomic computingrequires scientific and technological advances in a widevariety of fields, and new architectures that supporteffective integration of the constituent technologies.2. ConceptsBiological systems have inspired systems design in manyways—Artificial Intelligence, Artificial Neural Networks,Genetic Algorithms, Genetic Programming, and HolonicSystems to name a few. The most recent is the inspiration tocreate self-managing systems.2.1. Autonomic nervous systemThe human body’s Autonomic Nervous System (ANS) isthe part of the nervous system that controls the vegetativefunctions of the body such as circulation of the blood,intestinal activity and secretion, and the production ofchemical ‘messengers’, i.e. hormones, that circulate in

Database and XML Technologies

XML Twig Queries.- Ordered Backward XPath Axis Processing against XML Streams.- BPI-TWIG: XML Twig Query Evaluation.- On the Efficiency of a Prefix Path Holistic Algorithm.- Query Execution.- KSRQuerying: XML Keyword with Recursive Querying.- The XML-? XPath Processor: Benchmarking and Results.- XPath+: A Tool for Linked XML Documents Navigation.- XML Document Parsing and Compression.- A Data Parallel Algorithm for XML DOM Parsing.- Optimizing XML Compression.- XML Lossy Text Compression: A Preliminary Study.- XQuery.- XQuery Full Text Implementation in BaseX.- Recommending XMLTable Views for XQuery Workloads.- An Encoding of XQuery in Prolog.- Universal XForms for Dynamic XQuery Generation.- XML Transaction Management and Schema Design.- From Entity Relationship to XML Schema: A Graph-Theoretic Approach.- Atomicity for XML Databases.

Web, Web-Services, and Database Systems

GRIDs are both a new and an old concept. Many of the components have been the subject of R&D and some exist as commercial products. The GRIDs concept represents many different things to different people: metacomputing, distributed computing, advanced networking, distributed database, information retrieval, digital libraries, hypermedia, cooperative working, knowledge management, advanced user interfaces, mobile and pervasive computing and many others. More importantly, end-users see the GRIDs technology as a means to an end to improve quality, speed of working and cooperation in their field. GRIDs will deliver the required information in an appropriate form to the right place in a timely fashion. The novelty of GRIDs lies in the information systems engineering required in generating missing components and putting the components together. Ambient computing provides new possibilities in connectivity of a person (with or without sensors or data detectors) to a GRIDs environment allowing previously unimaginable possibilities in information delivery, data collection, command and control, cooperative working, communications, learning and entertainment.

A transaction model supporting complex applications in integrated information systems

The use of database systems in new applications, e.g. computer aided design, software engineering, etc, leads to new requirements for the transaction management. Main characteristics of such environments are long duration of transactions and teamwork. In this paper we introduce a concept for lang transactions which especially supports the cooperative work of groups on a common set of data. The transaction model has two levels: on the one hand the team has to be protected from the outside world, on the other hand mechanisms are required which allow controlled teamwork an common objects. In the latter case rigid synchronisation mechanisms as used in database systems are not applicable. A main concept for the support of teamwork and for design databases in general is a user-oriented version mechanism. This paper presents such a mechanism and its integration into the transaction model.

Expressing different conceptual models of join point selections in aspect-oriented design

When specifying pointcuts, i.e. join point selections, in Aspect-Oriented Software Development, developers have in different situations different conceptual models in mind. Aspect-oriented programming languages are usually capable to support only a small subset of them, but not all. In order to communicate aspect-oriented design among developers, though, it is inevitable that the underlying conceptual model used in its join point selections remains unchanged. As a solution to this dilemma, we detail three different conceptual models in this paper that are frequently used in aspect-oriented applications. These models are illustrated using sample implementations from existing literature. Then, we introduce corresponding modeling notations based on Join Point Designation Diagrams (JPDDs) which are capable to express join point selections complying to those models. Finally, we discuss the suitability of these notations to express a desired join point selection.

Objects, Components, Architectures, Services and Applications for a Networked World

The contents of this volume can best be described by an excerpt from the original Call for Papers for NODe 2002. Ever evolving and increasingly powerful information and communication technologies have substantially changed the nature of global relationships, the sources of competitive advantage, and the opportunities for economic and social development. The Internet, portable computers/devices and wireless communication technologies have turned the globe into an interconnected network of individuals, firms, organizations and governments communicating and interacting with each other through a variety of channels. NODe 2002 especially focuses on topics such as object-oriented (distributed) technologies, concepts and systems, agent-related technologies and concepts, advanced database systems and the Web, and E-commerce, including both the engineering and the use of Web-based application systems. Since Java and Smalltalk play a key role in the above-mentioned areas, we considered them to be of particular interest for the conference. As systems ought to be engineered well to be able to cope with the influx of the above-mentioned technologies in a positive way, the integrative factor of software architectures and component-driven technologies, especially their demands with regards to structures (patterns and architectures) and processes (enhanced life-cycles and workflows), form additional focuses of NODe 2002. However, as in the years before, NODe 2002 was open to questions and aspects of object-oriented and Internet-based technology in general and invited submissions related to a wide variety of topics in these areas.

Organizational Intelligence and Negotiation Based DAI Systems — Theoretical Foundations and Experimental Results

A steadily increasing number of researchers believes that so-called organizational multi agent systems are a key technology to support information and knowledge processing activities in cooperative, networked organizations. This, in turn, necessitates their integration with the underlying human-centred organization. The concept of an organization has emerged as central to the structuring of activities of both decentralized industrial and commercial conglomerates and collections of intelligent problem solvers within Distributed Artificial Intelligence (DAI) systems. Of late a new discipline has begun to emerge, that of Organizational Intelligence (OI). Organizational Intelligence demands a greater synthesis between the principles of Organization Theory (OT) and DAI, by the explicit incorporation of theories of both organizations and DAI into the field of OI. This paper concentrates on two rather important features of OI, namely organizational memory and learning capabilities. It will first discuss the theoretical foundations. Then it will be shown how the contract net approach can be extended to meet these demands. Finally, it will be proved by some experimental results that the increased intellectual capabilities of the extended contract net will substantially contribute to the performance as well as the quality of solution processes.

Parametric introductions

Aspect-oriented software development allows the programmer to identify and treat separately concerns that, subsequently, can be woven to different target applications. For this, aspect-oriented languages like AspectJ and Hyper/J provide mechanisms for defining and composing such crosscutting concerns. An introduction is a mechanism for defining certain static crosscutting concerns, i.e., concerns that affect the type of the application they are woven to. This paper discusses the implementations of introductions in AspectJ and Hyper/J and reveals their limitations by presenting typical examples of static crosscutting code that cannot be handled adequately by them. To solve these deficiencies we will present the concept of parametric introduction, which are introductions that rely on parameters that are evaluated during weavetime.

Agent technologies, infrastructures, tools, and applications for e-services: revised papers from the International Conference Net.ObjectDays (NODe 2002) Agent-Related Workshops, Erfurt, Germany, 07-10 October 2002

Keynotes.- Software Agents: The Future of Web Services.- Building Automated Negotiators.- Emergence in Cyberspace: Towards the Evolutionary Self-Organizing Enterprise.- Regular Papers.- Requirements Analysis in Tropos: A Self-Referencing Example.- A Mechanism for Dynamic Role Playing.- Agent UML Class Diagrams Revisited.- The Behavior-Oriented Design of Modular Agent Intelligence.- Engineering JADE Agents with the Gaia Methodology.- Designing Peer-to-Peer Applications: An Agent-Oriented Approach.- Introducing Pattern Reuse in the Design of Multi-agent Systems.- Specifying Reuse Concerns in Agent System Design Using a Role Algebra.- Comparison of Some Negotiation Algorithms Using a Tournament-Based Approach.- State-Based Modeling Method for Multiagent Conversation Protocols and Decision Activities.- A Framework for Inter-society Communication in Agents.- Action Recognition and Prediction for Driver Assistance Systems Using Dynamic Belief Networks.- Collaborative Agent System Using Fuzzy Logic for Optimisation.- A Self-Organizational Management Network Based on Adaptive Resonance Theory.- Mobile Software Agents for Location-Based Systems.- Partner Detection and Selection in Emergent Holonic Enterprises.- A Multi-agent System for E-insurance Brokering.- An XML Multi-agent System for E-learning and Skill Management.- Integrating Mobile and Intelligent Agents in Advanced E-commerce: A Survey.- An Agent-Oriented Approach to Industrial Automation Systems.- Multi-agent Model to Control Production System: A Reactive and Emergent Approach by Cooperation and Competition between Agents.- Integrating Agents in Software Applications.- A Foundational Analysis of Software Robustness Using Redundant Agent Collaboration.