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Semantic Web Services: A Brokerage Architecture
Proposal
Gökay Burak AKKUŞ
Computer Engineering, M.S. Thesis Proposal, 2004
Thesis Supervisor: Dr. Ayşe BENER
It is obvious that the Internet could be more useful than it is today. One possible route forward is that
of W3C’s Semantic Web initiative, which states that the future Web will be a new network that is
interpretable by the machines. And the full power of the new network will be realized when agent
programs are created that collect content from diverse sources, process the information and exchange
the results with other programs. The effectiveness of such software agents will increase exponentially,
as more machine-readable web content and automated services become available.
Basic technologies will include XML, UDDI and SOAP together with Web Services, Ontologies, and
OWL. XML, UDDI and SOAP are known industry standards. But the core elements –Semantic Web
and Ontologies, in the thesis should be clarified. An ontology is a specification of a representational
vocabulary for a shared domain of discourse and it includes a vocabulary of terms, and some
specification of their meaning. The goal is to create an agreed-upon vocabulary and semantic
structure for exchanging information about that domain. Each word used (for a relation or property)
must explicitly declare its ontological commitment. In the case of the Semantic Web this means that
we have to use URIs to achieve precision and to show its ontological commitment in the case of
properties. The ontological commitment governs the use and meaning of the word, and as a
consequence the applications' use of it. Further, an ontology is only a formal approximation of the
world. Another important property is that the ontology is language-dependent while the
conceptualization is language-independent. Two different ontologies might share the same
conceptualization of a thing, e.g. the concept of price, but might map different words from their
vocabulary to that concept. This means that it will become possible to achieve interoperability between
different ontologies if the conceptualization is the same in some sense. But it also means that if two
applications use the same words it does not mean that they map to the same conceptualization.
Web services promise the dynamic creation of loosely coupled information systems that are built over
reusable components.
However, current approaches are logically centralized and lack key
functionality, especially to locate, select and bind services meeting certain criteria of quality. So, there
is a need of an architecture that allows clients of services to automatically select and bind with desired
services, and with minimal intervention by the designers and implementers or the end users. Further,
current approaches support no memory of service bindings and interactions, except whatever a
specific application programmer may include in an ad hoc manner. The clients cannot learn from their
past interactions to improve their future decisions, as there is no system that provides support from
learning from the past interactions of others.
Although much data handling and underlying protocols are automated through current standards, key
aspects that support flexible decision-making with respect to the composition and selection of services
are still treated in an ad hoc manner. The aim of this thesis is mainly to make these aspects
systematic by constructing methodologies over sample service brokerage architecture and generating
storable blueprints of workflows concerning web processes.
Web Processes are next generation workflow technology to facilitate the interaction of organizations
with markets, competitors, suppliers, customers etc. supporting enterprise-level and core business
activities. Web processes describe how Web services are connected to create reliable and
dependable business solutions and allow businesses to describe sophisticated processes that can
both consume and provide Web services. The role of Web processes within the enterprise is to
simplify the integration of business and application processes across technological and corporate
domains.
In this thesis, it is claimed that software development needs to progress from hand-made line-at-a-time
techniques to methodologies that support reuse of existing software assets. In other words, software
development needs to shift from paradigms that are purely creational to others that support
compositional approaches. So, new software development paradigms are remarkable: Componentbased software engineering, Agent-based software engineering. These two disciplines are related and
dependent upon each other. In the future, passive software components will be liberated by the
proactive and social nature of agents.
A framework for building up ontologies-based services and specialized brokering services to find Web
services, which form up the main element to be processed by software agents, will be proposed and a
guide for evolving in the path of next generation web services will be introduced from the Navigable
Web, to the Semantic Web and then Trusted Web, and finally Dynamic and Transparent Web. The
proposed framework will be compared with the existing specialized brokerage architectures such as
MONET project (Mathematical Web services Brokerage). The criteria of comparison will be
completeness of the architecture, flexibility, fault tolerance issues, applicability of the architecture
using current technology, side-effects to the environment and business processes, the level of domain
independence, and the level of human intervention.
References:
1. Fensel D, 2000, Ontologies: Silver Bullet for Knowledge Management and Electronic
Commerce, URL: http://www.cs.vu.nl/%7Edieter/ftp/paper/silverbullet.pdf
2. Paul A. Buhler, José M. Vidal, 2002, Semantic Web Services as Agent Behaviors
3. Danny Ayers, 2 July 2004, The Missing Webs, AIG SIGSEMIS Bulletin Vol. 1
No. 2 pp. 18-24.
4. E. Michael Maximillien, Munindar P. Singh, 2002, Conceptual Model of Web Service
Reputation, ITR-0081742
5. Sheila A. McIlraith, Tran Coa Son, Honglei Zeng, 2001, Semantic Web Services, IEEE
Intelligent Systems pp. 46-53.
6. W3C, 2000, Semantic Web, http://www.w3.org/sw/.