Sergey A. Stupnikov

Heterogeneous Information Model Unification as a Pre-requisite to Resource Schema Mapping

An innovative technique for formation of collaborative consortia of enterprises in virtual organizations (VO) is considered. The technique is based on semantic integration of relevant enterprise information systems (EIS) in the VO specification treated as a subject mediator over the EISs involved. The paper explains how the canonical model for the VO specification is synthesized. Main part of the paper is devoted to the presentation of the process of EIS resource information models semi-automatic mapping into the canonical one assisted by the Heterogeneous Information Model Unifier. It is important to note that the Model Unifier is a universal tool that assists in development of mapping of various kinds of information. The process of mapping includes construction of a compiler from a resource model into the canonical one with the help of metacompilation tools. The mediation technique presented is applied in the astronomical Russian Virtual Observatory (RVO).

Extensible canonical process model synthesis applying formal interpretation

The current period of IT development is characterized by an explosive growth of diverse information representation languages. Applying integration and composition of heterogeneous information components it is required to develop the canonical information model serving for adequate expression of semantics of various information models used in the environment encompassing required heterogeneous components. Basic principles of the canonical model synthesis include fixing of its kernel, constructing the kernel extensions for each specific information model of the environment so that this extension together with the kernel could be refined by this information model, and forming the canonical model as a union of all such extensions. Previously these principles have been successfully applied to the synthesis of structural and object canonical models. This paper applies this technique to synthesis of the process canonical model. The method proposed is based on interpretation of process model semantics in logics, and specifically, in the Abstract Machine Notation that made possible to construct provable refinements of process specifications. This method has been applied to the environment of process models defined by workflow patterns classified by W.M.P. van der Aalst. Thus the canonical process model synthesized possesses a property of completeness with respect to broad class of process models used in various Workflow Management Systems as well as the languages used for process composition of Web services.

Query Rewriting Using Views in a Typed Mediator Environment

Query rewriting method is proposed for the heterogeneous information integration infrastructure formed by the subject mediator environment. Local as View (LAV) approach treating schemas exported by sources as materialized views over virtual classes of the mediator is considered as the basis for the subject mediation infrastructure. In spite of significant progress of query rewriting with views, it remains unclear how to rewrite queries in the typed, object-oriented mediator environment. This paper embeds conjunctive views and queries into an advanced canonical object model of the mediator. The “selection-projection-join” (SPJ) conjunctive query semantics based on type specification calculus is introduced. The paper demonstrates how the existing query rewriting approaches can be extended to be applicable in such typed environment. The paper shows that refinement of the mediator class instance types by the source class instance types is the basic relationship required for establishing query containment in the object environment.

Synthesis of the canonical models for database integration preserving semantics of the value inventive data models

Recently families of sets of dependencies treated as the Datalog extensions were discovered for which the interpretation of queries becomes tractable. Such families are intended for inference of new, unknown values in the process of query answering. This paper considers such decidable classes of dependencies as the assets for creation of new data models (called in the paper the value inventive data models) analogously to axiomatic extension of the canonical model kernel used so far for unification of structured and object data models aimed at heterogeneous database integration. The paper examines the decidable classes of dependencies reflecting the semantics of value inventive data models considering such classes to be the extensions of the canonical data model kernel. The issue of identifying of decidable subsets of the canonical model extension is considered.

Conceptual approach to astronomical problems

New technical capabilities have brought about the sweeping growth of the amount of data acquired by the astronomers from observations with different instruments in various parts of the electromagnetic spectrum. We consider conceptual approach to be a promising tool to efficiently deal with these data. It uses problem domain knowledge to formulate the tasks and develop problem-solving algorithms and data analysis methods in terms of domain concepts without reference to particular data sources, and thereby allows solving certain problems in general form. We demonstrate the benefits of conceptual approach by using it to solve problems related to search for secondary photometric standard candidates, determination of galaxy redshifts, creation of a binary and multiple star repository based on inhomogeneous databases, and classification of eclipsing binaries.We formulate and solve these problems over specifications of astronomical knowledge units such as photometric systems, astronomical objects, multiple stars, etc., and define them in terms of the corresponding problem domains independently of the existing data resources.

Rule-Based Multi-dialect Infrastructure for Conceptual Problem Solving over Heterogeneous Distributed Information Resources

An approach for applying a combination of the semantically different rule-based languages for interoperable conceptual programming over various rule-based systems (RS) and relying on the logic program transformation technique recommended by the W3C Rule Interchange Format (RIF) is presented. Such approach is coherently combined with the heterogeneous data base integration applying semantic rule mediation. The basic functions of the infrastructure implementing the multi-dialect conceptual specifications by the interoperable RS and mediator programs are defined. The references to the detailed description of the infrastructure application for solving complex combinatorial problem are given. The research results show the usability of the approach and of the infrastructure for declarative, resource independent and re-usable data analysis in various application domains.

Rule-Based Specification and Implementation of Multimodel Data Integration.

An approach for rule-based specification of data integration using RIF-BLD logic dialect that is a recommendation of W3C is presented. The approach allows to combine entities defined in different sources represented in different data models (relational, XML, graph-based, document-based) in the same rule. Logical semantics of RIF-BLD provides for unambiguous interpretation of data integration rules. The paper proposes an approach for implementation of RIF-BLD rules using IBM High-level integration language (HIL) as well. Thus data integration rules can be compiled into MapReduce programs and executed over Hadoop-based distributed infrastructures.

Semantics and Verification of Entity Resolution and Data Fusion Operations via Transformation into a Formal Notation

During all the period of development of data integration methods and tools the issues of formal semantics definition and verification were arising. Three levels of integration can be distinguished: data model integration, schema matching and integration and data integration proper. This paper is aimed at development of methods and tools for formal semantics definition and verification on the third level – level of data proper. An approach for definition of formal semantics for high-level data integration programs is proposed. The semantics is defined using a transformation into a formal specification language supported by automatic/interactive provers. The semantics is applied for verification of structured data integration workflows. Workflow properties to be verified are presented as expressions of the specification language chosen. After that a semantic specification of the data integration workflow is verified w.r.t. required properties. A practical aim of the work is to define a basis for formal verification of data integration workflows during problem solving in various integration environments.

Multi-dialect Workflows

The results presented in this paper contribute to the techniques for conceptual representation of data analysis algorithms as well as processes to specify data and behavior semantics in one paradigm. An investigation of a novel approach for applying a combination of semantically different platform independent rule-based languages (dialects) for interoperable conceptual specifications over various rule-based systems (RSs) relying on the rule-based program transformation technique recommended by the W3C Rule Interchange Format (RIF) is extended here. The approach is coupled also with the facilities for heterogeneous information resources mediation. This paper extends a previous research of the authors [1] in the direction of workflow modeling for definition of compositions of algorithmic modules in a process structure. A capability of the multi-dialect workflow support specifying the tasks in semantically different languages mostly suited to the task orientation is presented. A practical workflow use case, the interoperating tasks of which are specified in several rule-based languages (RIF-CASPD, RIF-BLD, RIF-PRD) is introduced. In addition, OWL 2 is used for the conceptual schema definition, RIF-PRD is used also for the workflow orchestration. The use case implementation infrastructure includes a production rule-based system (IBM ILOG), a logic rule-based system (DLV) and a mediation system.

Value Reconciliation in Mediators of Heterogeneous Information Collections Applying Well-Structured Context Specifications

Method for value reconciliation in Local as Views (LAV) mediators of heterogeneous information collections applying well-structured specifications is presented. This approach extends a procedure for heterogeneous information sources registration at subject mediators with LAV organization. Conflicts in value semantics and representation in contexts of the mediator and a collection should be recognized and explicitly specified. According to the proposed method, value semantics contexts should be defined for the mediator and for a collection. In such context for each value kind a type is to be specified that includes a generic function converting values from a collection context into the mediator context (and/or back). Each type attribute having the respective value semantics is to be typed with such type definition. Such structuring of type attribute semantics definition gives significant economy in development of value conversion functions needed to reconcile values between the mediator and collection contexts.