Semantic integration is an active area of research in several disciplines, such as databases, information-integration, and ontologies. This paper provides a brief survey of the approaches to semantic integration developed by researchers in the ontology community. We focus on the approaches that differentiate the ontology research from other related areas. The goal of the paper is to provide a reader who may not be very familiar with ontology research with introduction to major themes in this research and with pointers to different research projects. We discuss techniques for finding correspondences between ontologies, declarative ways of representing these correspondences, and use of these correspondences in various semantic-integration tasks 1. ONTOLOGIES AND SEMANTIC INTE-

Ontology mapping, alignment, and translation has been an active research component of the general research on semantic integration and interoperability. In our talk, we gave our own classification of different topics in this research. We talked about types of heterogeneity between ontologies, various mapping representations, classified methods for discovering methods both between ontology concepts and data, and talked about various tasks where mappings are used. In this extended abstract of our talk, we provide an annotated bibliography for this area of research, giving readers brief pointers on representative papers in each of the topics mentioned above. We did not attempt to compile a comprehensive bibliography and hence the list in this abstract is necessarily incomplete. Rather, we tried to sketch a map of the field, with some specific reference to help interested readers in their exploration of the work to-date. 1 Survey Articles For more detailed descriptions and bibliography of the field we refer the readers to several recently published surveys:

With the rising popularity of Web services, both academia and industry have invested considerably in Web service description standards, discovery, and composition techniques. The standards based approach utilized by Web services has supported interoperability at the syntax level. However, issues of structural and semantic heterogeneity between messages exchanged by Web services are far more complex and crucial to interoperability. It is for these reasons that we recognize the value that schema/data mappings bring to Web service descriptions. In this paper, we examine challenges to interoperability; classify the types of heterogeneities that can occur between interacting services and present a possible solution for data interoperability using the mapping support provided by WSDL-S. We present a data mediation architecture using the extensibility features of WSDL and the popular SOAP engine, Axis 2. 1.

In such contexts as the Semantic Web, the components of an application increasingly rely on ontological models and content knowledge developed and maintained by independent contributors. These components also are designed to be building blocks of various applications. We advocate the use of a mediating component that defines and processes the knowledge transformations required to enable application components to exchange, and inter-operate on, knowledge and data. We present our approach and associated tools to support developers (1) in defining mapping relations between the ontologies involved in their application and (2) in running a mapping interpreter to mediate content knowledge and data among the corresponding ontology-based components.

The number of ontologies and knowledge bases covering different domains and available on the World-Wide Web is steadily growing. As more ontologies are available, it is becoming harder, and not easier, for users to find ontologies they need. How do they evaluate if a particular ontology is appropriate for their task? How do they choose among many ontologies for the same domain? We argue that allowing users on the Web to annotate and review ontologies is an important step in facilitating ontology evaluation and reuse for others. However, opening the system to everyone on the Web poses a problem of trust: Users must be able to identify reviews and annotations that are useful for them. We discuss the kinds of metadata that we can collect from users and authors of ontologies in the form of annotations and reviews, explore the use of an Open Rating System for evaluating ontologies and knowledge sources, and present a brief overview of a Web-based browser for Protégé ontologies that enables users to annotate information in ontologies. Ontologies On The Web Scale The number of ontologies and knowledge bases covering different domains and available on the World-Wide Web is steadily growing. Ontologies constitute the backbone of the Semantic Web and their number is steadily growing. The Swoogle crawler, 1 for example, indexes more than 4000 ontologies at the time of this writing. It is commonly agreed that one of the reasons ontologies became popular is because they hold a promise of facilitating interoperation between software resources by virtue of being shared agreed-upon descriptions of domains used by different agents. Such interoperation is, for example, a key requirement for the Semantic Web to succeed. Suppose we are developing a Semantic Web service that uses an ontology. If we choose to reuse an existing ontology to support our service rather than to create a new one, we get the interoperation with the others using the same ontology “for free. ” In addition,

We introduce a multiple-view tool called AlViz, which supports the alignment of ontologies visually. Ontologies play an important role for interoperability between organizations and for the semantic web because they aim at capturing domain knowledge in a generic way and provide a consensual understanding of a domain. Alignment is the process where for each entity in one ontology we try to find a corresponding entity in the second ontology with the same or the closest meaning. Existing ontology alignment tools do not adequately provide a way for users to analyse the results. While many alignment tools generate lists of mappings it is difficult to analyse these alignments without examining every pairwise correspondence in the output files and even then it is an overwhelming task. We propose the use of visualization techniques to facilitate user understanding of the ontology alignment results. AlViz is implemented as a tab plug-in for Protégé.

With the rising popularity of Web services, both academia and industry have invested considerably in Web service description standards, discovery, and composition techniques. The standards based approach utilized by Web services has supported interoperability at the syntax level. However, issues of structural and semantic heterogeneity between messages exchanged by Web services are far more complex and crucial to interoperability. It is for these reasons that we recognize the value that schema/data mappings bring to Web service descriptions. In this paper, we examine challenges to interoperability; classify the types of heterogeneities that can occur between interacting services and present a possible solution for data interoperability using the mapping support provided by WSDL-S, a key driver behind SAWSDL. We present a data mediation architecture using the extensibility features of WSDL and the popular SOAP engine, Axis 2.

The semantic web envisions the Internet as a globally linked database, one that supports data interoperability and machine readable semantics. The “back-bone ” of the semantic web is structural representations of domains of knowledge in the form of ontologies. A critical prerequisite to supporting this global information exchange is that mappings must exist between domain related ontologies. The process of mapping one ontology to another is far from a fully automated task. Generally, it is necessary for a human to verify and fine-tune the mappings generated by ontology mapping tools. The research focus has been primarily on the automation of this process and has largely ignored the user. We believe that in order for mapping tools to move beyond research labs we need to begin focusing on the user’s needs during the mapping process. In this project, we discuss the first step towards reaching this goal, a pilot user study where we investigate the human decision making process during an ontology mapping task. Based on the data collected, our goal is to gain a detailed understanding of the aforementioned process and develop design requirements that if implemented, will help reduce the cognitive load of the mapping users.

Abstract. Recently, the advantages of metamodeling as a foundation for the graphical specification of ontologies have been recognized by the semantic web community. This has lead to a number of activities concerned with the development of graphical modeling approaches for the Web Ontology Language based on the Meta Object Facility (MOF) and the Unified Modeling Language (UML). An aspect that has not been addressed by these approaches so far is the need to specify mappings between heterogenous ontologies. With an increasing number of ontologies being available, the problem of specifying mappings is becoming more important and the rationales for providing model based graphical modeling support for mappings is the same as for the ontologies themselves. In this paper, we propose a MOF-based metamodel for mappings between OWL DL ontologies as well as a UML based graphical language for modeling mappings independent of a specific mapping formalism. 1

With the rise of model-driven software development, more and more development tasks are being performed on models. A rich variety of modeling tools is available supporting different tasks, such as model creation, model simulation, model checking, and code generation. Seamless exchange of models among different modeling tools increasingly becomes a crucial prerequisite for effective software development processes. Due to lack of interoperability, however, it is often difficult to use tools in combination, thus the potential of model-driven software development cannot be fully utilized – unless we find some scalable way of integration. We are aiming at providing a semantic infrastructure for model-based tool integration, enabling to facilitate any tool appropriate for the modeling task at hand. The key innovations provided are a set of scalable architectural model integration patterns supported by a highlevel metamodel integration language, thus going beyond existing low-level model transformation approaches. Ontology-based metamodel integration considerably lowers the manual effort required for tool integration, enabling a novel synergic use of technologies