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.
9033123
Process Aggregation Using Web Services
This paper examines the opportunities and challenges related to data and process integration architectures in the context of Web Services. A primary goal of most enterprises in today's economic environment is to improve productivity by streamlining and aggregating business processes. This paper illustrates how integration architectures based on Web Services offer new opportunities to improve productivity that are expedient and economical. First, the paper introduces the technical standards associated with Web Services and provides business example for illustration. Abstracting from this example, we introduce a concept we call Process Aggregation that incorporates data aggregation and workflow to improve productivity. We show that Web Services will have a major impact on Process Aggregation, making it both faster and less expensive to implement. Finally, we suggest some research directions relating to the Process Aggregation 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.
2677077
Context interchange: new features and formalisms for the intelligent integration of information
The Context Interchange strategy presents a novel perspective for mediated data access in which semantic conflicts among heterogeneous systems are not identified a priori, but are detected and reconciled by a context mediator through comparison of contexts axioms corresponding to the systems engaged in data exchange. In this article, we show that queries formulated on shared views, export schema, and shared “ontologies” can be mediated in the same way using the Context Interchange framework. The proposed framework provides a logic-based object-oriented formalsim for representing and reasoning about data semantics in disparate systems, and has been validated in a prototype implementation providing mediated data access to both traditional and web-based information sources.
38159603
The COntext INterchange (COIN) Project: Data Extraction and Interpretation from Semi-Structured Web Sources
3110757
Context Knowledge Representation and Reasoning in the Context Interchange System
The Context Interchange Project presents a unique approach to the problem of semantic conflict resolution among multiple heterogeneous data sources. The system presents a semantically meaningful view of the data to the receivers (e.g. user applications) for all the available data sources. The semantic conflicts are automatically detected and reconciled by a Context Mediator using the context knowledge associated with both the data sources and the data receivers. The results are collated and presented in the receiver context. The current implementation of the system provides access to flat files, classical relational databases, on-line databases, and web services. An example application, using actual financial information sources, is described along with a detailed description of the operation of the system for an example query.
17041428
Context interchange in a client-server architecture
Abstract Many organizations today require information from diverse information systems, and government efforts are moving toward a national information infrastructure for sharing information. However, the systems used by these organizations lack the capabilities to meaningfully translate information among semantically heterogeneous environments. Because the meaning of data acquired from a source environment is usually different from that needed or expected in the receiver's environment, the effectiveness of information exchange is dependent on the system's capability for context interchange, i.e., the representation, exchange, comparison, and transformation of context knowledge. We show here a practical means for developing context interchange capabilities in a client-server architecture by use of semantic values (i.e., data and their context(as the unit of data exchange. The key components in this architecture are the context mediator server, whose job is to identify and construct the semantic values being sent, determine when the exchange is meaningful, and convert the semantic values to the form required by the client (i.e., receiver), and the data environment server, whose job is to assist in the location, access, development, and maintenance of the context knowledge for all clients and servers.
7986917
Translation Validation: From DC+ to C*
Translation validation is 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 produced 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. 
 
In this paper we demonstrate the feasibility of translation validation for industrial code generators from DC+ -a widely used intermediate format for synchronous languages- to C. We explain the compilation pattern from DC+ to C and advocate new abstraction techniques for a fragment of first order logic as part of the automation of our approach.
14822655
Translation Validation
17738680
Hierarchical Automata as Model for Statecharts
Statecharts are a very rich graphical specification formalism supported by the commercial tool Statemate. Statecharts comprises powerful concepts such as interlevel transitions, multiple-source/multiple-target transitions, priority amongst transitions and simultaneous execution of maximal non-conflicting sets of transitions. Every add-on tool which is supposed to be linked with the Statemate tool have to deal with the rather involved semantics of these concepts. We propose extended hierarchical automata as an intermediate format to facilitate the linking of new tools to the Statemate environment, whose main idea is to devise a simple formalism with a more restricted syntax than statecharts which nevertheless allows to capture the richer formalism. We define the format, give operational semantics to it, and translate statecharts to it.
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.
43742881
Erratum ("The small model property: how small can it be?" Volume 178, Number 1 [2002], pages 279-293)