5563723
Data Integration Using Web Services
In this paper we examine the opportunities for data integration in the context of the emerging Web Services systems development paradigm. The paper introduces the programming standards associated with Web Services and provides an example of how Web Services can be used to unlock heterogeneous business systems to extract and integrate business data. We provide an introduction to the problems and research issues encountered when applying Web Services to data integration. We provide a formal definition of aggregation (as a type of data integration) and discuss the impact of Web Services on aggregation. We show that Web Services will make the development of systems for aggregation both faster and less expensive to develop. A system architecture for Web Services based aggregation is presented that is representative of products available from software vendors today. Finally, we highlight some of the challenges facing Web Services that are not currently being addressed by standards bodies or software vendors. These include context mediation, trusted intermediaries, quality and source selection, licensing and payment mechanisms, and systems development tools. We suggest some research directions for each of these challenges.
14385577
Context mediation on Wall Street
The paper reports on a practical implementation of a context mediator for the fixed income securities industry. The authors describe industry circumstances and the data and calculation services (DCS) mediator developed and deployed in the early 1990s. The mediator was designed as an interpretive engine controlled by a static declarative knowledge structure and client preference data. In addition to heterogeneous, autonomous data sources, the mediator integrated autonomously developed local and remote procedural components. Client access to both data and computational resources were provided through an active conceptual model. Structural and semantic context conversions were used to integrate disparate components and to support varying client needs. Lessons learned from the implementation and usage of this mediator provide insight into the requirements for a successful context mediator.
38331434
Rule Discovery for Query Optimization
11984448
Context interchange: overcoming the challenges of large-scale interoperable database systems in a dynamic environment
Research in database interoperability has primarily focused on circumventing schematic and semantic incompatibility arising from autonomy of the underlying databases. We argue that, while existing integration strategies might provide satisfactory support for small or static systems, their inadequacies rapidly become evident in large-scale interoperable database systems operating in a dynamic environment. This paper highlights the problem of receiver heterogeneity, scalability, and evolution which have received little attention in the literature, provides an overview of the Context Interchange approach to interoperability, illustrates why this is able to better circumvent the problems identified, and forges the connections to other works by suggesting how the context interchange framework differs from other integration approaches in the literature.
41563606
Conceptualizing Semantic Interoperability: A Perspective From the Knowledge Level
Currently, there is a proliferation of database integration approaches in response to the need to achieve semantic interoperability in heterogeneous, distributed and autonomous environments. To date, however, we lack abstract, formal descriptions of the task of semantic interoperation, independent of idiosyncratic implementation details. Such abstract descriptions are needed to aid our understanding of these various complex systems that are being constructed. Therefore, we argue that a knowledge level perspective of interoperable systems is desirable. The knowledge level serves as an abstract specification of what a system should do and facilitates the design and analysis of complex systems. In this paper, we show how an interoperable system, based on the Context Interchange Architecture, may be specified in terms of first-order logic which is an ideal specification language at the knowledge level. This specification represents a theoretical ideal which serves to formalize and communicate the key ideas behind the Context Interchange Approach, unencumbered by the details, limitations and compromises of specific implementations. As such, it provides a rigorous basis for implementing such systems. Similar specifications may also be developed for other models of interoperable systems. As a result, we have a rigorous means of understanding, comparing and analyzing these complex systems.
5683523
A Metadata Approach to Resolving Semantic Conflicts
In this paper we describe a rule-based approach to semantic specification that can be used to establish semantic agreement between a source and receiver. Query processing techniques use these specifications along with conversion routines and query modification to guarantee correct data semantics. This work also examines the effect of changing data semantics. These changes may occur at the source of the data or they may be changes in the specifications of the dat,a semantics for the application, Methods are described for detecting these changes and for determining if the database can continue to supply meaningful data to the application. These methods for semanlic reconcilia2ion are necessary for determining logical connectivity between a data source (database) and a data receiver (application). Though described in terms of the source-receiver model, these techniques can also be used for semantic reconciliation and schema integration for multidatabase systems. Keywords[data dictionaries, heterogeneous databases, metadata, query modification, schema integration, semantic conflicts]
43742881
Erratum ("The small model property: how small can it be?" Volume 178, Number 1 [2002], pages 279-293)
9192328
Translation Validation for Synchronous Languages
Translation validations an alternative to the verification of translators (compilers, code generators). Rather than proving in advance that, the compiler always produces a target code which correctly implements the source code (compiler verification), each individual translation (i.e. a run of the compiler) is followed by a validation phase which verifies that the target code producted on this run correctly implements the submitted source program. In order to be a practical alternative to compiler verification, a key feature of this validation is its full automation.
6090717
From Testing Theory to Test Driver Implementation
In this article we describe the theoretical foundations for the VVT-RT test system (Verification, Validation and Test for Reactive Real-Time Systems) which supports automated test generation, test execution and test evaluation for reactive systems. VVT-RT constructs and evaluates tests based on formal CSP specifications [6], making use of their representation as labelled transition systems generated by the CSP model checker FDR [3]. The present article provides a sound formal basis for the development and verification of high-quality test tools: Since, due to the high degree of automation offered by VVT-RT, human interaction becomes superfluous during critical phases of the test process, the trustworthiness of the test tool is an issue of great importance. The VVT-RT system will therefore be formally verified so that it can be certified for testing safety-critical systems. The present article represents the starting point of this verification suite, where the basic strategies for test generation and test evaluation used by the system are formally described and verified. VVT-RT has been designed to support automation of both untimed and real-time tests. The present article describes the underlying theory for the untimed case. Exploiting these results, the concepts and high-level algorithms used for the automation of real-time tests are described in a second report which is currently prepared [14]. At present, VVT-RT is applied for hardware-in-the-loop tests of railway and tramway control computers.
33236770
Formal Verification of Stabilizing Systems
This paper links too formerly rather disjoint areas: formal verification and stabilization. Stabilization is a vitally emerging paradigm in fault tolerant distributed computing; formal verification investigates mathematically rigorous techniques to reason about systems.
6836947
Deductive verification of stabilizing systems