Semantic Data Integration in P2P Systems

Abstract

Abstract. In this paper, we study the problem of data integration in P2P systems. Differently from the traditional setting, data integration in these systems is not based on the existence of a global view. Instead, each peer exports data in terms of its own schema, and information integration is achieved by establishing mappings among the various peer schemas. We present a framework that captures this general architecture, and then we discuss the problem of characterizing the semantics of such framework. We show that the usual approach of resorting to a first-order logic intepretation of P2P mappings, leads both to a poor modeling of the whole system, and to undecidability of query answering, even for mappings of a restricted form. This motivates the need of a new semantics for P2P system. We then present a novel proposal, based on epistemic logic, and show that not only it adequately models the interactions among peers, but it also supports decidable query answering. In particular, for the restricted form of mapping mentioned above, query answering is polynomial with respect to the size of data stored in the peers.

A service-oriented system for distributed data querying and integration on Grids

“…According to these trends, several peer-to-peer data integration formalisms have been introduced [18][19][20][21][22][23]. All these systems focus on an integration approach not based on a global centralized schema.…”

Multi-modal nonmonotonic logics of minimal knowledge

“…In particular, several recent studies in the formalization of peer-to-peer distributed systems [2,5,12,7,6] have clearly pointed out that the intended semantics of information in this kind of applications is naturally captured by an epistemic logic approach based on the principle of minimal knowledge, in which each system is modeled as an autonomous epistemic agent, and the exchange of information in the system is represented by epistemic sentences that express the relationships among the epistemic states of the different agents. Moreover, such studies highlight that, in order to fully represent the peculiar aspects of such application scenarios, we need a logic incorporating first-order quantification that is also able to formalize typical nonmonotonic reasoning features of the epistemic agents [6].…”

A Semantic Overlay Network for P2P Schema-Based Data Integration

“…Little effort has been made with respect to rich semantic representations of data and query functionalities beyond simple keyword searches. Only in the last few years, several peer-to-peer data management infrastructures allowing for semantic data sharing have been emerging [1], [2], [4]. All those systems focus on a decentralized integration approach (i.e.…”

“…In the domain of semantic integration, formal integration models have been defined, query languages have been designed, schema mediation techniques have been proposed [1], [2], [3], [4], [5], [6]. These works however take little care of the underlying network whose topology is more than often abstracted.…”