Application driven mediation middleware of the Russian Virtual Observatory for scientific problem solving over multiple heterogeneous distributed information resources

Dmitry Briukhov^I, Leonid Kalinichenko^I, Dmitry Martynov^I, Nikolay Skvortsov^I,

Sergey Stupnikov^I, Alexey Vovchenko^I, & Olga Zhelenkova^II

^IInstitute of Informatics Problems, Russian Academy of Sciences, Vavilov st. 44-2, Moscow, Russia, e-mail: brd@ipi.ac.ru, leonidk@synth.ipi.ac.ru, domartynov@gmail.com, nskv@ipi.ac.ru, ssa@ipi.ac.ru, itsnein@gmail.com

^IISpecial Astrophysical Observatory, Russian Academy of Sciences, Nizhnij Arkhyz, Zelenchukskaya, Karachaevo-Cherkesia, Russia, e-mail: olbo@nm.ru

The paper considers the middleware architecture of subject mediators in the hybrid grid-infrastructure of the Russian virtual observatory (RVO) for scientific problem solving over a set of heterogeneous distributed information resources (such as databases, services, ontologies) integrated by the mediators. The RVO hybrid infrastructure is constructed as a binding of the AstroGid VO system developed in the UK and of the middleware supporting subject mediators developed at the Institute of Informatics Problems of RAS. In the mediator middleware an approach driven by applications is implemented. According to this approach for a class of applications a specification of subject domain (a mediator) is formed independently of the pre-existing information resources. The following activities are supported by the application-driven mediation middleware. Specification of a mediator is a result of consolidation effort of community related to the respective application domain. Semantic identification (ontologically based), mapping and registration of relevant resources in the mediator are provided by the Information Resource Registration tool of the middleware. Mappings of information models of heterogeneous information resources into the canonical model of the middleware is provided by the Information Model Unifier tool.

Integrated access to the resources registered at the mediator applying the mediator program rewriting system is provided by the Executive Engine of the mediation environment. Principles of rewriting of the mediator programs into the plans of their implementation over registered resources are considered. An example of implementation in the hybrid architecture of a subject mediator for solving of distant radio galaxies discovery problem is presented (http://synthesis.ipi.ac.ru/synthesis/projects/Z_DGS/). The paper shows how in the mediator architecture the complicated problems of semantic integration of information resources and of query rewriting are solved. The distinguishing features of the presented approach comparing to the well known prototypes of database integration in virtual observatories are overviewed. The middleware architecture of subject mediators is planned to be used for solving of the RVO problems.