服務導向架構 (Service-Oriented Architecture) 近年來被極度重視，服務導向架構藉由 Web Services 等標準化元件所組成，能使服務有彈性、可重複使用的透過網路供企業內部外部利用。 UDDI 為此架構中用於描述並發現服務的標準規範，提供服務提供者發佈網際服務、並提供服務要求者搜尋網際服務以及網際服務之相關資訊，因而讓網際服務可以被服務被要求者所使用。 BPEL 則可以描述商業流程，其中包含了與其他服務的互動。透過服務組合引擎則可以執行以 BPEL 描述之流程。由於這些流程可以呼叫其他網際服務，因此可以將許多各自獨立的網際服務組合到流程當中，並作為一個複合服務發佈於網際網路，達成服務組合 (Service Composition) 的目的。 本研究能針對記載於 UDDI 登錄資料庫中的服務進行服務品質 (QoS) 的偵測，檢測這些網際服務是否仍然可以正常提供服務，並設法檢測這些網際當前所提供的操作是否仍符合最初服務提供者發佈此服務時的狀態。同時並參考了 Extended Contract Net Protocol (ECNP) 設計一套機制，使得複合服務得以於 UDDI 登錄資料庫中找尋符合其需求的服務，將其作為候選服務 (Candidate Services)，並選出最合適的候選服務作為執行時使用的服務。用以確保複合服務的可靠性。 SOA (Service-Oriented Architecture) is the trend in recent year. SOA is composed of standard components such as web services. It makes services be used through Internet flexible and reusable. UDDI (Universal Description, Discovery, and Integration) is the standard specification for describing and discovering services. It provides the functions, which let Service Provider can publish Web Services, and let Service Requester can search Web Services and service’s information. By this mechanism, Web Services can serve their services to Service Requester. BPEL (Business Process Execution Language) is used to describe the business process including the interaction with other services. The business process can be executed by using Service Composition Engine and can be published to Internet as a Composite Service. It reaches the goal of Service Composition that enables one to aggregate existing services into a new composite service. We propose an approach to probe the QoS (Quality of Service) of services which be stored in UDDI Registry. And referring to ECNP (Extended Contract Net Protocol), we design a mechanism to find the candidate services groups of Composite Service, and select the suitable services from candidates. This mechanism ensures the reliability of Composite Service.
