In this poster, we present (i) a proposal for a metadata standard, known as Ontology Metadata Vocabulary (OMV) which is based on discussions in the EU IST thematic network of excellence Knowledge Web1 and (ii) two complementary reference

implementations which show the benefit of such a standard in

decentralized and centralized scenarios, i.e. the Oyster P2P

system and the Onthology metadata portal

Gómez-Pérez, A.

Hartmann, J.

Palma, R.

English

Servicio de Coordinación de Bibliotecas de la Universidad Politécnica de Madrid

Towards an Ontology Metadata Standard 
Raul Palma 
Facultad de Informática. Universidad 
Politécnica de Madrid 
Campus Montegancedo, s/n 28860 
Boadilla del Monte. Madrid. Spain 
34-913367439 
rpalma@fi.upm.es 
Jens Hartmann 
Institute AIFB 
University of Karlsruhe 
Germany 
49-721 608 6554 
hartmann@aifb.uni-karlsruhe.de 
Asunción Gómez-Pérezi 
Facultad de Informática. Universidad 
Politécnica de Madrid 
Campus Montegancedo, s/n 28860 
Boadilla del Monte. Madrid. Spain 
34-913367439 
asun@fi.upm.es 
ABSTRACT 
In this poster, we present (i) a proposal for a metadata standard, 
known as Ontology Metadata Vocabulary (OMV) which is based 
on discussions in the EU IST thematic network of excellence 
Knowledge Web1 and (ii) two complementary reference 
implementations which show the benefit of such a standard in 
decentralized and centralized scenarios, i.e. the Oyster P2P 
system and the Onthology metadata portal. 
Categories and Subject Descriptors 
I.2.4 [Knowledge Representation Formalisms and Methods]: 
Representation languages. 
K.6.4 [System Management]: Centralization/descentralization 
General Terms 
Management, documentation, design, reliability, experimentation, 
standardization. 
Keywords 
Ontology, Metadata, Peer-to-Peer, Repository 
1. INTRODUCTION 
Ontologies have undergone an enormous development and 
application in many domains within the last years, especially in 
the context of the Semantic Web. Currently however, efficient 
knowledge sharing and reuse, a pre-requisite for the realization of 
the Semantic Web vision, is a difficult task since it is hard to find 
and share existing ontologies because of the lack of standards for 
documenting and annotating ontologies with metadata 
information. Without an ontology-specific metadata developers 
are not able to exploit existing ontologies, which leads to 
problems of interoperability as well as duplicate efforts. Then, in 
order to provide a basis for an effective access and exchange of 
ontologies across the web it is necessary to agree on a standard 
for ontology metadata, that is a common set of terms and 
definitions describing ontologies, that is called metadata 
vocabulary. Furthermore, an appropriate technology infrastructure 
is required, e.g. tools and metadata repositories, compatible to the 
ontology metadata standard, must be developed to support the 
creation, maintenance and distribution of ontology metadata. 
2. OMV 
Some of the aspects captured by OMV2 (the complete ontology is 
                                                                 
1 http://knowledgeweb.semanticweb.org 
described in [1]) are similar to other metadata standards, like 
Dublin Core [2]. However, some important differences like the 
conceptual models (semantics) behind ontologies require a 
detailed analysis and a different representation of metadata about 
ontologies.  From a conceptual design point of view, OMV 
distinguishes between the OMV Core, which captures information 
relevant to the majority of ontology reuse settings and various 
OMV Extensions that allow ontology developers/users to specify 
task/application-specific ontology-related information.   
2.1 Overview 
OMV core distinguishes between an ontology conceptualisation 
and its implementation(s) in concrete representation languages. 
From an ontology engineering perspective, a person first develops 
such core idea of what should be modeled (and maybe how) in his 
mind. Further, this initial conceptualisation might be discussed 
with other persons and then, an ontology will be built using an 
ontology editor and stored in a specific format. Over time, several 
realizations of this initial conceptualisation might be created in 
many different formats, e.g. in RDF(S) or OWL. The two 
concepts are defined as follows: 
Ontology Conceptualisation: (OC) represents the (abstract) core 
model or idea behind an ontology. It describes the core properties 
of an ontology, independently of any implementation details.  
Ontology Implementation: An (OI) represents a specific 
realization of a conceptualisation. It describes properties of an 
ontology that are related to the realization or implementation.  
The distinction between the two concepts provides an efficient 
mechanism for the realization of several ontology management 
utilities, such as the tracking of several versions, the evolution 
flow of an ontology or the handling of different representations of 
the same knowledge model. OMV also models additional classes 
that are required to represent and support the reuse of ontologies 
by such metadata vocabulary, especially in the context of the 
Semantic Web. Hence, we modeled further classes and properties 
representing environmental information and relations such as: 
Party, Organisation, Person, OntologyType, LicenseModel,  
OntologyLanguage, etc. The main classes and properties of the 
OMV ontology are illustrated in Figure 1.  
3. USE CASES 
We shortly introduce two complementary applications based on 
OMV, namely the decentralised P2P system Oyster3 and the 
centralized metadata portal Onthology4, to show the benefits of 
using such a vocabulary in real life scenarios. Both applications 
                                                                                                           
2 OMV ontology is available at http://ontoware.org/projects/omv/ 
3 Available at http://oyster.ontoware.org/ 
4 http://www.onthology.org/ 
 
Demos and Posters of the 3rd European Semantic Web Conference 
(ESWC 2006), Budva Montenegro, 11th - 14th June, 2006 
have in common that they support single users and 
communities of users in identifying, reusing and providing 
ontology metadata. However, both applications are covering a 
variety of different tasks and have different usage perspective. For 
users who want to store metadata individually, a repository is 
required to which the user has full access and can perform any 
operation without any consequences to other users. In this 
situation a decentralised system is the technique of choice, as it 
allows the maximum of individuality while it still ensures 
exchange with other users. Centralized systems allow reflecting 
long-term community processes in which some ontologies 
become well accepted for a domain or community and others 
become less important. The benefit of connecting both systems 
lies mainly in the simple use of ontology metadata information 
existing within Oyster. So, while users are applying or even 
developing their own ontologies they can manage their own 
metadata along with other existing metadata in Oyster. If some 
metadata entries from Oyster have reached a certain confidence, 
they can be easily imported into Onthology.  
4. RELATED WORK 
We will briefly mention related metadata standards, in particular 
those relevant to the Semantic Web. The Dublin Core (DC) 
metadata standard [2] is a simple yet effective element set for 
describing a wide range of networked resources. The Reference 
Ontology [3] is a domain ontology that gathers, describes and 
links existing ontologies. However its focus is to characterize 
ontologies from the user point of view, and provides only a list of 
property-value pairs for describing ontologies. FOAF [4] 
provides a way to create machine-readable Web homepages for 
people, groups, companies and other things. The Semantic Web 
search engine SWOOGLE [5] makes use of particularly metadata 
which can be extracted automatically. There exist some similar 
approaches to our proposed solution to share ontologies, but in 
general their scope is quite limited. E.g. the DAML ontology 
library [6] provides a catalog of DAML ontologies that can be 
browsed by different properties. The FIPA ontology service [7] 
defines an agent wrapper of open knowledge base connectivity. 
Finally the SchemaWeb Directory [8] is a repository for RDF 
schemas expressed in RDFS, OWL and DAML+OIL. 
5. CONCLUSIONS AND FUTURE WORK 
A key issue for sharing knowledge on the Semantic Web is to 
reuse existing ontologies. Our contribution aims at facilitating 
reuse of ontologies which was previously unknown for ontology 
developers by providing an Ontology Metadata Vocabulary 
(OMV) and two applications for decentralized (Oyster) and 
centralized (Onthology) sharing of ontology metadata based on 
OMV. Our current work is DEMO [9], a framework for the 
development and deployment of ontology metadata, which 
comprises OMV and an inventory of methods to collaboratively 
extend OMV in accordance to the requirements of an emerging 
community of users, and tools for metadata management. Finally, 
our future work includes many challenges such as the application 
of OMV extensions, the evaluation of the application of OMV in 
different scenarios and pushing OMV to a community standard. 
6. ACKNOWLEDGMENTS 
Our thanks to our partners from the EU project Knowledge Web 
for their present and future collaboration. Especially we would 
like to thank Elena Paslaru (FUB), Denny Vrandecic (AIFB).  
7. REFERENCES 
[1] J. Hartmann, R. Palma OMV-Ontology Metadata 
Vocabulary for the semantic web.2005.v1.0. 
http://omv.ontoware.org 
[2] Dublin Core. http://dublincore.org. 
[3] J. Arpirez et al. Reference Ontology and (ONTO)2 Agent: 
The Ontology Yellow Pages. Knowledge and Information 
Systems. Volume 2. 2000. 387-412.  
[4] FOAF- “Friend Of A Friend”-. http://www.foaf-
project.org 
[5] Li Ding et al. Swoogle: A search and metadata engine for the 
semantic web. In Proceedings of the Thirteenth ACM 
Conference on Information and Knowledge Management, 
pages 58–61, November 2004. 
[6] DAML Ontology repository. http://www.daml.org/ontologies 
[7] H. Suguri et al. Implementation of fipa ontology service. In 
Proc. of the Workshop on Ontologies in Agent Systems, 5th 
Int. Conf. on Autonomous Agents Montreal, Canada, 2001. 
[8] SchemaWeb directory. http://www.schemaweb.info/ 
[9] J. Hartmann et al. DEMO-A Design Environment for 
Metadata Ontologies. In proc. of ESWC2006. June 2006 
                                                                 
i Additional Authors: York Sure (AIFB), M. Carmen Suarez-
Figueroa (UPM), Peter Haase (AIFB) and Rudi Studer (AIFB). 
Figure 1. OMV overview 


Towards an Ontology Metadata Standard

In this poster, we present (i) a proposal for a metadata standard, known as Ontology Metadata Vocabulary (OMV) which is based on discussions in the EU IST thematic network of excellence Knowledge Web1 and (ii) two complementary reference implementations which show the benefit of such a standard in decentralized and centralized scenarios, i.e. the Oyster P2P

system and the Onthology metadata portal

Archivo Digital UPM

DEMO-A Design Environment for Metadata Ontologies. In

Implementation of fipa ontology service.

Of A Friend”-.

Palma OMV-Ontology Metadata Vocabulary for the semantic web.2005.v1.0. http://omv.ontoware.org

Reference Ontology and (ONTO)2 Agent: The Ontology Yellow Pages. Knowledge and Information Systems.

Swoogle: A search and metadata engine for the semantic web.

Towards an Ontology Metadata Standard

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