一套結合語意網與Web 2.0技術的服務搜尋與組裝系統

Abstract

網路服務(Web Service)在近幾年蓬勃發展使得網路服務的數量與種類變得複雜龐大，然而由UDDI所提供的服務搜尋機制並無法有效找到使用者所需要的網路服務，如何精確地搜尋出合適的網路服務成了一大困難與挑戰。近年來，許多研究致力於結合語意網技術來實現自動化的服務搜尋與自動化的服務組裝。 然而以目前語意網為基礎的搜尋機制下，敘述邏輯(Description Logics)扮演了很重要的腳色，敘述邏輯廣泛地被應用在網路服務的描述，及以知識本體語言OWL之定義。但是對於一般的使用者來說，敘述邏輯過於複雜而不易理解，而造成系統使用上的門檻障礙。另外知識本體的維護也是一個重要的議題，傳統由小部分管理者負責的維護方式有兩個缺點: (1)知識本體的更新所需時間過長而且欠缺完整性，(2)管理者與一般使用者對於知識本體的解讀有所落差，造成更新的知識本體可能並不是使用者所需要。 在本論文中，我們的目的為三： (1)改進先前以語意網為基礎的服務組合架構服務搜尋與組裝系統，降低語意網應用系統的使用門檻 (2)提出一個具體的方法論有效地維護知識本體 (3)運用所提出的系統架構，我們以旅遊業為例，實作出一個客製化的旅遊行程規劃系統；動態組合現有網路服務，滿足使用者的需求。 我們使用現有的語意網與網路服務技術：WSDL、SWRL、OWL、BPEL4WS，結合Web2.0技術作為系統架構的基礎，我們希望可以提供使用者一套易於使用，共同維護的服務搜尋與組裝系統。我們相信，透過結合語意網與Web2.0技術，本論文能改進現階段地語意網應用系統架構，對於語意網技術未來的發展走向提供了一個實質上的參考。

Web Services which are specific functionalities and can be combined to meet a particular user's needs have become a mature technology in the past few years. However, the discovery and search mechanism provided by UDDI based on keyword matching may lead to an ambiguous answer. It is a challenge to target the suiting Web services precisely. Semantic Web technology provides another option for service matching. It enables a service profile to be described according to its functionalities in OWL, which is based on Description Logics. Recently, researchers are dedicated on studying Semantic Web technology as a primary tool for ontology-based Web Services searching and invocation. With help of precise semantics description, Web Services are able to be utilized automatically. Under such a Semantic Web search mechanism, Web Services profile and domain ontology are both described by Description Logics. However, potential users often do not have any knowledge about Description Logics. That creates a huge gap and critically imposes high entrance barriers for the user. Besides, ontology maintenance is another important issue for Semantic Web applications. Ontology maintenance is a time-consuming job. Ontology maintenance is usually controlled by a small group of people. But it has several drawbacks: (1) the addition can be time-consuming and lack of completion and (2) the ontology maintainer read the concept in the different manner from how potential user does. Accordingly, sometimes concepts become obsolete by the time they enter the ontology. In the long run, ontology maintenance cannot be ignored especially in such a Semantic Web application. In this thesis, we proposed: (1) an open system architecture to lower the entrance barriers of Semantic Web applications, (2) a practical approach to ontology maintenance, and (3) a new prototype system. The Traveller was implemented based on our ontology- based architecture and related methodologies. With the service composition and execution architecture, the user is able to find suiting Web Services, invoke services by defining BPEL4WS, and participate in collaborative ontology maintenance without knowing any Semantic languages.