Traditional science searched for new objects and phenomena that led to discoveries. Tomorrow's science will combine together the large pool of information in scientific archives and make discoveries. Scientists are currently keen to federate together the existing scientific databases. The major challenge in building a federation of these autonomous and heterogeneous databases is system integration. Ineffective integration will result in defunct federations and under utilized scientific data. Astronomy, in particular, has many autonomous archives spread over the Internet. It is now seeking to federate these, with minimal effort, into a Virtual Observatory that will solve complex distributed computing tasks such as answering federated spatial join queries. In this paper, we present SkyQuery, a successful prototype of an evolving federation of astronomy archives. It interoperates using the emerging Web services standard. We describe the SkyQuery architecture and show how it efficiently evaluates a probabilistic federated spatial join query. 1.

We are currently witnessing the emerging of a new generation of software systems: Federated information systems. Their main characteristic is that they are constructed as an integrating layer over existing legacy applications and databases. They can be broadly classified in three dimensions: the degree of autonomy they allow in integrated components, the degree of heterogeneity between components they can cope with, and whether or not they support distribution. Whereas the communication and interoperation problem has come into a stage of applicable solutions over the past decade, semantic data integration has not become similarly clear. This report

InfoSleuth is an agent-based system that can be configured to perform many di#erent information management activities in a distributed environment. InfoSleuth TM agents provide a number of complex query services that require resolving ontology-based queries over dynamically changing, distributed, heterogeneous resources. These include distributed query processing, locationindependent single-resource updates, event and information monitoring, statistical or inferential data analysis, and trend discovery in complex event streams. It has been used in numerous applications, including the Environmental Data Exchange Network and the Competitive Intelligence System. Keywords: Multi-agent systems, agent-based systems, information agents, heterogeneous data, query processing, information subscription. 1. Introduction In the past 15-20 years, numerous products and prototypes have regularly appeared to provide uniform access to heterogeneous data sources. As a result, that access to...

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This paper describes how a set of autonomous computational agents can cooperate in providing coherent management of transaction workflows in environments where there are many diverse information resources. The agents use models of themselves and of the resources that are local to them. Resource models may be the schemas of databases, frame systems of knowledge bases, domain models of business environments, or process models of business operations. Models enable the agents and information resources to use the appropriate semantics when they interoperate. This is accomplished by specifying the semantics in terms of a common ontology. We discuss the contents of the models, where they come from, and how the agents acquire them. We then describe a set of agents for telecommunication service provisioning and show how the agents use such models to cooperate. The agents implement virtual state machines, and interact by exchanging state information. Their interactions produce an implementation of relaxed transaction processing. 1

Redux 0 is a subset of the full REDUX model[7]. The latter performs problem solving. In contrast Redux 0 does not and acts only as a decision maintenance server. It takes objects of types defined in an ontology of decision components and maintains dependencies between them. Redux 0 is domain-independent. The dependency relationships are maintained on the basis of proposition type and not content, except for some string matching. Redux 0 servers are proposed as a mechanism for federating heterogeneous design agents by encapsulating their design decisions within a simple model and providing coordination services, especially for design revision. This proposal is described within the context of the SHADE and PACT projects. 1 Introduction The SHADE and PACT[10] projects take a federating[6, 9] approach to the problem of coordinating distributed design. Individual software systems, used by the people to accomplish their part of the design, are idiosyncratic and may not work with e...

In this paper we describe how a set of autonomous computational agents can cooperate in providing coherent management of information in environments where there are many diverse information resources. The agents use models of themselves and of the resources that are local to them. Resource models may be the schemas of databases, frame systems of knowledge bases, or process models of business operations. Models enable the agents and resources to use the appropriate semantics when they interoperate. This is accomplished by specifying the semantics in terms of a common ontology. We discuss the contents of the models, where they come from, and how the agents acquire them. We then describe a set of agents for telecommunication service provisioning and show how the agents use such models to cooperate. Their interactions produce an implementation of relaxed transaction processing. 1

s Service (CAS) registry number (7439-97-6), "raw" CAS number (dashes removed---7439976), and common name ("quicksilver "). Within an ontology, each class has one or more slots, where each slot has a conceptual domain name with a canonical value domain over which all agents communicate when referring to that slot. This mapping problem has several manifestations, which we relate roughly in the order they have been addressed in the literature (insofar as they are addressed at all): ffl Traditional: Mapping between schemas can take place by imposing a view on that information and/or defining functions to translate the data from one value domain to another, as is currently done in relational databases, e.g., [9]. This type of mapping provides little support for semantics, but rather relies on the structure of the data. ffl Ontology-based: A common ontology is defined with well-specified semantics for the concepts it describes. Mapping between a schema and an ontology is done on a semantic...

Abstract. We discuss the applicability of schema integration techniques developed for tightly-coupled database interoperation to interoperation of databases stemming from different modelling contexts. We illustrate that in such an environment, it is typically quite difficult to infer the real-world semantics of remote classes from their definition in remote databases. However, defining relationships between the real-world se-mantics of schema elements is essential in existing schema integration techniques. We propose to base database interoperation in such environ-ments on instance-level semantic relationships, to be defined using what we call object comparison rules. Both the local and the remote classifi-cations of the appropriately merged instances are maintained, allowing for the derivation of a global class hierarchy if desired. 1

Abstract. Database transformations arise in many di erent settings including database integration, evolution of database systems, and implementing user views and data-entry tools. This paper surveys approaches that have beentaken to problems in these settings, assesses their strengths and weaknesses, and develops requirements on a formal model for specifying and implementing database transformations. We also consider the problem of insuring the correctness of database transformations. In particular, we demonstrate that the usefulness of correctness conditions such as information preservation is hindered by theinteractions of transformations and database constraints, and the limited expressive power of established database constraint languages. We conclude that more general notions of correctness are required, and that there is a need for a uniform formalism for expressing both database transformations and constraints, and reasoning about their interactions. Finally we introduce WOL, a declarative language for specifying and implementing database transformations and constraints. We brie y describe the WOL language and its semantics, and argue that it addresses many of the requirements on a formalism for dealing with general database transformations. 1