以共識為基礎的服務搜尋機制

Abstract

網路服務(Web services)廣泛的被應用在電子商務、網格服務(Grid Services)與電子化政府等各種不同的領域，它通常分散在異質網路環境之中，而且能夠透過整合(composition)被加以再利用並衍生出其他功能更強大的服務。有效率的服務搜尋機制是網路服務能否被充分利用的先決條件，然而網路服務的搜尋首先遭遇到的問題就是搜尋機制通常根據服務本身所提供的說明標籤、介面的特徵或者服務的功能性描述進行搜尋，無法根據服務本身所包含的內容(content)本身進行搜尋。換言之，服務使用者需要靠其他額外的判斷準則，方能在許多重複或者是相似的服務之中選取真正適合的服務；其次、目前的研究趨勢在於如何動態的搜尋，並同時整合既有的網路服務。唯大部分現有的服務搜尋方法，無論是由服務的功能性或者非功能性觀點進行搜尋，都無法有效解決認知差距所造成之搜尋不準確的問題。因為不論服務使用者對網路服務進行搜尋，或者服務提供者對服務進行宣傳時，對服務內容通常抱持著不同的主觀期待或是偏好，由於雙方對於服務內容有不同的觀點或評價，導致正確搜尋服務的效率顯得不盡人意。本研究提出一個以共識為基礎的服務搜尋方法，嘗試來降低因認知差距所引起的搜尋不準確問題。此法能夠收集個人主觀的意見，以模糊化的方式加以表達，並協助服務的使用者與提供者在進行搜尋之前先達成一個共識，藉以提升服務搜尋的準確率。本法採用一系列的模糊群體決策制定理論以及語意網路(Semantic Web)的技術，使得不同的主觀意見得以整合成為一個共識並利用它對服務內容進行分類與搜尋。本法可以重複的被執行，因此新的主觀意見得以被納入並且持續提升搜尋的效率。此外除了將研究開發成雛型系統之外，也將利用各種不同的數據實際測試之，期待實驗的結果能夠展示出本研究所提方法的效能。

Web services are used for developing and integrating highly distributed and heterogeneous systems in different domains such as e-business, Grid services, and e-government systems. Service discovery is a crucial process for Web service utilization. However, the issues associated with service discovery that involves the Web service having data repositories are not well addressed by the existing methods which focus on service capabilities, interface signatures, or functionalities. These methods are inadequate to identify appropriate services among the services which have similar functionalities, so it requires service consumers to include additional aspects (i.e. content of service or reputation) to evaluate the services. An effective service discovery mechanism is able to support the identification of the required services in a dynamic environment and form composite services that provide the required functionality. The service consumers and providers often have different views on the content of services. The existing service discovery approaches, based on either functional or non-functional attributes, do not address the issues associated with the impact of the diverse preferences and subjective expectations of the service consumers and providers which are generally used in searching for or in advertising Web services. This study attempts to alleviate such diversity by proposing a consensus-based service discovery approach to model subjective and fuzzy opinions. This will assist service consumers and providers in reaching a common consensus so that the efficiency of service discovery can be increased. The approach which is based on fuzzy group decision making methods and semantic web technologies can be executed iteratively and therefore further fuzzy opinions and preferences can be added to improve the precision of Web service discovery. The proposed approach will be implemented as a prototype system and to be tested through various experiments in order to demonstrate the effectiveness of the proposed approach.