Mike P. Papazoglou

A semantic meta-modelling approach to schema transformation

This paper presents an intermediate meta-model that consists of a set of generic meta-classes that capture and describe the semantics of a variety of data models. A model is described by a set of intermediate model meta-classes (organized in the form of a directed acyclic graph (DAG) to achieve extensibility y), while irtst antes of these meta-classes are used to describe a schema in a given data model. The proposed approach supports dynamic meta-schema comparison and transformation by employing special-purpose transformation rules.

On the Representation of Objects with Polymorphic Shape and Behaviour

In this paper we present the concept of roles as an extension to object-oriented database models in which identifiable groups of objects are allowed to evolve by assuming transient behavior, while preserving their identity. This mechanism can be used to implement multi-faceted, or polymorphic, objects by allowing the same object to be represented under different perspectives — possibly at discrete points in time — with each perspective having its own state and behavior. The concept of roles is used to implement dynamic properties and aspects of objects and provides for added modeling power and flexibility.

On building a hyperdistributed database

Sharing data among disparate databases has so far mostly been achieved through some form of ad-hoc schema integration. This approach becomes less tractable as the number of participating database increases. Therefore, the complexity of making autonomous heterogeneous databases interoperate is dependent on adequately addressing the autonomy and heterogeneity issues. In this paper, we describe a prototype that implements an approach which addresses these issues in the context of large multidatabase systems. In particular, we describe a scheme that builds a Hyperdistributed Database using a two-staged approach. We also describe how conglomerations of databases are formed, modified, and evolved.

TrActorS: a transactional actor system for distributed query processing

A transaction management model for distributed information systems that utilizes actor-like objects (TrActor) which deviate from conventional actors in their objects types, messages types, and mail queue is described. The objects are used in conjunction with distributed blackboarding techniques for addressing the process of reasoning about the need for cooperation and negotiation between the disparate information sources in a distributed information network. A variant of the nested transaction model is proposed as an information processing framework for the management model. A language for this framework is also proposed, and the feasibility of this approach is demonstrated by means of a comprehensive example.<<ETX>>

The Next Generation of Information Systems: From Data to Knowledge

The next generation of information systems - from intelligence to distribution and cooperation.- A data and operation model for advanced database systems.- An object-oriented data model to represent uncertainty in coupled artificial intelligence - database systems.- Common architectures for databases and knowledge-based systems.- The construction of maintainable knowledge bases.- Adding qualitative reasoning to an organizational database for management decision support.- Building human-centered intelligent cooperative information systems with IKEA.- Database organisation for qualitative analysis: the NUDIST(t) system.- Using a prolog engine to integrate multiple knowledge sources: the KCM/Help-desk project.- From relations to objects: A translation methodology for an object oriented front-end to RDBMSs.- A framework for cooperative adaptable information systems.- Problem solving in federative environments: The FRESCO concept of cooperative agents.- Heterogeneous database integration architecture based on a conversation theoretic skeleton.- Coarse-grained distributed agents for transparent access to remote information.- A forward-chaining information framework.- Using negotiation and coordination in multiagent Intelligent Cooperative Information Systems.- A distributed cooperative agents architecture for software development.- Knowledge selection in large knowledge bases.

R-OK: a reflective model for distributed object management

This paper introduces the R-OK (Reflective Object Knowledge) Model. Using this model, a new information system may be constructed by interconnecting pre-existing systems. The process is enabled by the introduction of a layer of metalevel software that surrounds each local DBMS, and which knows a systems capabilities and functionality. An object-oriented approach is taken to the description of the metalevel with the introduction of a group of special reflective objects that are used to describe and monitor every domain object in the system. Metaobjects allow the specification and implementation of a newly composed system to be intertwined. In this way a newly composed information system can draw upon the functionality of already existing systems.<<ETX>>

Language support for long-lived concurrent activities

Providing a general purpose programming environment that supports the definition of, and exercises control over, the flow of execution of long-running activities is highly beneficial for a variety of client/server distributed data-intensive applications. In this paper, we present a Transaction-Oriented Work-Flow Environment (TOWE) for the programming of long-lived activities through a set of class libraries. The TOWE is based on an amalgamation of object-oriented programming with distributed interprocess communication concepts. The concurrency abstractions provided by TOWE are objects, acting like processes, and involve an asynchronous, location-independent, mode of process invocation coupled with data-driven synchronization of processes.

A semantic-based nested transaction model for intelligent and cooperative information systems

Intelligent and cooperative information systems (ICIS) involve upgraded models for transaction support for large distributed data/knowledge intensive applications. The use of long-lived transactions results in the introduction of a flexible transaction model which employs weak integrity and optimistic commit mechanisms for transactions relying on compensating and contingency transactions to recover from potential semantic failures. An open-nested transaction model for ICIS is introduced. It provides linguistic facilities for defining and controlling long-lived complex transactions (comprising related units of work) by taking into account the semantics of distributed computations. The fact that the proposed transaction model is grafted on to an appropriately extended concurrent object-oriented programming language allows exhibiting a high degree of parallelism inherent in distributed transaction-oriented applications.<<ETX>>

A configurable approach for object sharing among multidatabase systems

The work presented in this research paper concentrates on the issues of determining the way of schema integration and knowledge organization to support interoperation in multidatabase systems (MDBSS). In particular the structure of the Data Correspondence Descriptor (DCD) is addressed aa the part of the knowledge base of each database to store schema correspondences and conflict resolutions. We also describe an experimental CABLE system, which demonstrates a configurable approach for object sharing among multiple database systems based their associated knowledge base. organizing inter-schema correspondences and object sharing. To demonstrate the methodology and techniques, we have developed a software prototype called CABLE a configurable approach for object sharing among multiple objectoriented database systems. The remainder of this paper is organized as follows: Section ‘2 gives an overview of our multidatabase structure. In Section 3, we outline the classification of correspondence between types, attributes and methods. Section-4 proposes a way to organize the inter-schema correspondences using data correspondence descriptor (DCD) approach. Section 5 explains the CABLE prototype to demonstrate our methodology discussed in this paper. Finally, Section 6 presents our conclusions and future research direct ions.

On the duality of distributed database and distributed AI systems

Distributed Database (DDB) and Distributed Artificial Intelligence (DAI) technologies have been conceived to addresses a variety of inherently complex problems involving spatial distribution. Although the types of problems addressed by these two technologies are quite different the technologies themselves present many similarities. In this paper we argue that DDB and DAI systems may be considered as duals of each other. The principal conclusion is that neither discipline has reached the point of maturity and that it would be useful to think in terms of systems developed by using a crossfertilization of these two disciplines. This paper focuses predominantly on DAI to DDB systems. 1 Mot ivat ion the technology transfer from for Coordinated Problem Solving To function effectively large organizations have to handle large volumes of information. To this end autcmated information servers have been deployed at an ever increasing rate within organizational functions or departments as the most effective way of dealing with this task. Typically, large companies (such as banks, corporate organizations, multi-nationals, etc) have developed over time independent information sysPermission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial edventqje, tha ACM copyright notice end the title of the publication and its data appaar, and notice is given that copying ia by permission of the Association for Computing Machinery. To copy otherwisa, or to rapublish, r, and/or specific permission. CIKM ’93-1 l/93/D. c., USA