The Cover PagesThe OASIS Cover Pages: The Online Resource for Markup Language Technologies
Advanced Search
Site Map
CP RSS Channel
Contact Us
Sponsoring CP
About Our Sponsors

Cover Stories
Articles & Papers
Press Releases

XML Query

XML Applications
General Apps
Government Apps
Academic Apps

Technology and Society
Tech Topics
Related Standards
Created: June 16, 2005.
News: Cover StoriesPrevious News ItemNext News Item

DERI Announces Submission of Web Services Modeling Ontology (WSMO) to W3C.


The Digital Enterprise Research Institute (DERI), a leading European research institute in the field of Semantic Web and Semantic Web services technology, has announced the submission of its Web Services Modeling Ontology (WSMO) to the World Wide Web Consortium (W3C). The multi-part submission package was made on April 04, 2005 by five institutions: DERI Innsbruck at the Leopold-Franzens-Universität Innsbruck, Austria; DERI Galway at the National University of Ireland, Galway, Ireland; British Telecom (BT, UK), The Open University (UK), and SAP AG (Germany).

The Web Service Modeling Ontology, according to DERI's announcement, "has been under development over the past two years within the WSMO working group. It provides a comprehensive framework for addressing Semantic Web services challenges and it is designed to help overcome the current problems of Enterprise Application Integration (EAI) and Service-Oriented Architectures (SOA). WSMO provides a conceptual framework and a formal language for semantically describing all relevant aspects of Web services in order to facilitate the automation of discovering, combining and invoking electronic services over the Web."

The Web Service Modeling Ontology Primer presented as part of the Member Submission describes the objective of WSMO as an attempt "to solve the application integration problem for Web services by defining a coherent technology for Semantic Web services. WSMO takes the Web Service Modeling Framework (WSMF) as starting point and further refines and extends its concepts. In order to achieve automated discovery, composition, and execution of Web services a conceptual model alone is insufficient. In addition, a formal language is required to write down annotations of Web services according to the conceptual model. Logical inference-mechanisms can be applied to the descriptions in this language. In order to allow appropriate, satisfactorily logic-based reasoning on Semantic Web services, the description language has to provide reasonable expressivity, together with well-defined formal semantics. The Web Service Modeling Language (WSML) is a family of languages which formalizes WSMO."

Three primary prose specifications are included in the WSMO Submission. The Web Services Modeling Ontology (WSMO) document provides ontological specifications for the core elements of Semantic Web services. This document "describes the overall structure of WSMO by its four main elements: ontologies, which provide the terminology used by other WSMO elements; Web service descriptions, which describe the functional and behavioral aspects of a Web service; goals that represent user desires; and mediators, which aim at automatically handling interoperability problems between different WSMO elements. Along with introducing the main elements of WSMO, the syntax of the formal logic language used in WSMO is provided."

The Web Service Modeling Language (WSML) document provides the language to formally describe all the elements defined in WSMO. It "introduces the Web Service Modeling Language WSML which provides a formal syntax and semantics for the Web Service Modeling Ontology WSMO. WSML is based on different logical formalisms, namely: Description Logics, First-Order Logic and Logic Programming, which are useful for the modeling of Semantic Web services. WSML consists of a number of variants based on these different logical formalisms, namely WSML-Core, WSML-DL, WSML-Flight, WSML-Rule and WSML-Full. WSML-Core corresponds with the intersection of Description Logic and Horn Logic. The other WSML variants provide increasing expressiveness in the direction of Description Logics and Logic Programming. Finally, both paradigms are unified in WSML-Full, the most expressive WSML variant."

WSML "is specified in terms of a normative human-readable syntax. Besides the human-readable syntax, WSML has an XML and an RDF syntax for exchange over the Web and for interoperation with RDF-based applications. Furthermore, we provide a mapping between WSML ontologies and OWL ontologies for interoperation with OWL ontologies through a common semantic subset of OWL and WSML."

The Web Service Execution Environment (WSMX) document included in the submission describes "an execution environment that enables discovery, selection, mediation, invocation and interoperation of Semantic Web Services and provides a reference implementation of WSMO. The development process for WSMX includes defining its conceptual model (i.e. WSMO), modeling its execution semantics (implemented by a dynamic execution semantic engine capable of interpreting any formal definition of system behaviour provided by third parties) and designing the WSMX system architecture. For the initial version of WSMX a complete architecture including discovery, mediation, selection and invocation components has been designed including all required supporting components enabling exchange of messages between the requesters and the providers of services."

A 'Resource Manager' dederibed in WSMX is responsible for the management of the repositories that store definitions of any WSMO entity (Web services, goals, ontologies and mediators) and non-WSMO related objects in WSMX. Currently WSMX provides five repositories: Web Service Repository, Goal Repository, Ontology Repository, Mediator Repository and Data Repository. This document also recognizes that ebXML and UDDI repositories can be used for WSMX data persistence."

The WSMO Member Submission suggests that W3C consider the technology as "an input for work in a new Semantic Web Services Description Working Group at W3C. Although WSMO "has been developed and deployed in collaboration with a number of industrial partners and research groups making up the WSMO working group, further enhancements are planned in the light of feedback from the W3C, knowledge and insights from real world case studies, and from ongoing work in related research projects and networks of excellence."

W3C has acknowledged receipt of the WSMO Member Submission but has not yet allocated any resources to the issues addressed by it. The W3C Team Comment on Web Service Modeling Ontology (WSMO) Submission by Carine Bournez notes that the overall design, which "relies on a simple Class/Sub-Class/Attributes/Types of attributes data model, is not based on W3C recommendations in the Semantic Web area, such as OWL and RDF. The notion of choreography in WSMO is obviously very far from the definition and scope presented in WS-CDL, and there is also no connection to any description language at lower level, like WSDL." Therefore, W3C "would like to see more background for the whole piece of work, by means of real use cases for example, to describe the problems that this framework is trying to solve."

Bibliographic Information

The WSMO Submission request to W3C consists of five documents:

WSMO Design Principles

From the Web Service Modeling Ontology (WSMO) specification Introduction: "Appropriate frameworks for Semantic Web services need to integrate the basic Web design principles, those defined for the Semantic Web, as well as design principles for distributed, service-orientated computing of the Web. WSMO is therefore based on the following design principles:

  • Web Compliance: WSMO inherits the concept of URI (Universal Resource Identifier) for unique identification of resources as the essential design principle of the Word Wide Web. Moreover, WSMO adopts the concept of Namespaces for denoting consistent information spaces, supports XMLand other W3C Web technology recommendations, as well as the decentralization of resources.

  • Ontology-Based: Ontologies are used as the data model throughout WSMO, meaning that all resource descriptions as well as all data interchanged during service usage are based on ontologies. Ontologies are a widely accepted state-of-the-art knowledge representation, and have thus been identified as the central enabling technology for the Semantic Web. The extensive usage of ontologies allows semantically enhanced information processing as well as support for interoperability; WSMO also supports the ontology languages defined for the Semantic Web.

  • Strict Decoupling: Decoupling denotes that WSMO resources are defined in isolation, meaning that each resource is specified independently without regard to possible usage or interactions with other resources. This complies with the open and distributed nature of the Web.

  • Centrality of Mediation: As a complementary design principle to strict decoupling, mediation addresses the handling of heterogeneities that naturally arise in open environments. Heterogeneity can occur in terms of data, underlying ontology, protocol or process. WSMO recognizes the importance of mediation for the successful deployment of Web services by making mediation a first class component of the framework.

  • Ontological Role Separation: Users, or more generally clients, exist in specific contexts which will not be the same as for available Web services. For example, a user may wish to book a holiday according to preferences for weather, culture and childcare, whereas Web services will typically cover airline travel and hotel availability. The underlying epistemology of WSMO differentiates between the desires of users or clients and available services.

  • Description versus Implementation: WSMO differentiates between the descriptions of Semantic Web services elements (description) and executable technologies (implementation). While the former requires a concise and sound description framework based on appropriate formalisms in order to provide a concise for semantic descriptions, the latter is concerned with the support of existing and emerging execution technologies for the Semantic Web and Web services. WSMO aims at providing an appropriate ontological description model, and to be complaint with existing and emerging technologies.

  • Execution Semantics: In order to verify the WSMO specification, the formal execution semantics of reference implementations like WSMX as well as other WSMO-enabled systems provide the technical realization of WSMO.

  • Service versus Web service: A Web service is a computational entity which is able (by invocation) to achieve a users goal. A service in contrast is the actual value provided by this invocation. WSMO provides means to describe Web services that provide access (searching, buying, etc.) to services. WSMO is designed as a means to describe the former and not to replace the functionality of the latter.

Principal References

Hosted By
OASIS - Organization for the Advancement of Structured Information Standards

Sponsored By

IBM Corporation
ISIS Papyrus
Microsoft Corporation
Oracle Corporation


XML Daily Newslink
Receive daily news updates from Managing Editor, Robin Cover.

 Newsletter Subscription
 Newsletter Archives
Bottom Globe Image

Document URI:  —  Legal stuff
Robin Cover, Editor: