- 學位論文
以Petri Net為基礎的網路服務組合前置驗證及簡化方法
A Petri Net-based Verification and Simplification Approach for Web Services Composition
摘要
網路服務組合是一個透過現存網路服務間的資訊共享、同步活動和協同合作所產生的新興分散式開發架構，運用工作流程來組合網路服務是目前最常見的解決方式。然而以流程為基礎的網路服務組合有很大的可能會因為流程設計的錯誤而產生deadlock、non-reachable等問題，導致網路服務組合在執行時期發生嚴重錯誤。這些流程結構設計的問題應該在網路服務組合執行之前透過驗證來察覺並更正。此外以流程為基礎的網路服務組合可能存在不必要的流程設計而影響網路服務組合的執行效能。 本研究提出一個以Petri Net為基礎的網路服務組合前置驗證及簡化方法，此方法包含塑模、驗證、簡化三個階段。首先以Petri Net配合工作流程樣板塑模網路服務組合；再結合safeness、reachability、deadlock三項Petri Net性質定義出網路服務組合結構正確性驗證模型，檢驗網路服務組合；最後運用流程簡化規則簡化網路服務組合。 在網路服務組合前置驗證及簡化方法的實作上，本研究透過BPEL文件與PNML文件的轉換完成網路服務組合的Petri Net塑模；再個別以Coverability Tree、Incidence Matrix and State Equation和Transitive Matrix分析方法驗證PNML文件的上述三項Petri Net性質。最後以網路服務組合代數方法配合簡化規則簡化BPEL文件。 本研究結果顯示，運用網路服務組合前置驗證及簡化方法可以確保網路服務組合流程設計的正確性及簡潔性，並且增加網路服務組合的可靠性。
並列摘要
Web services composition is a new distributed develop framework by sharing information, synchronizing activities and collaboration among existing Web services. Utilizing workflow to compose Web services is the most popular solution. While process-based Web services composition may take place some issues such as deadlock and non-reachable because of wrong flow design and result serious errors at Web services composition run time. These flow structure design problem should thorough verification to detect and correct before Web services composition execution. Besides, process-based Web services composition may have redundant flow design to effects Web services composition execution performance. This research presents a Petri Net-based verification and simplification approach for Web services composition. The approach consists of three steps involve modeling、verification and simplification. First, utilizing Petri Net to model Web services composition with workflow patterns. Then, combining safeness、reachability and liveness to define a Web services composition structure correctness verification model for verifying Web services composition. Finally, utilizing flow simplified rules to simplify Web services composition. About the implementation of the Petri Net-based verification and simplification approach for Web services composition, this research achieves Petri Net modeling of Web services composition by a series conversion between BPEL document and PNML document. Then, verifying above three Petri Net properties of PNML document individually by Coverability Tree、Incidence Matrix and State Equation and Transitive Matrix analysis method. Finally, utilizing Web services composition algebraic approach to simplify BPEL document with flow simplified rules. This research result using the Petri Net-based verification and simplification approach for Web services composition can assure the correctness and succinct of Web services composition flow design and enhance the reliability of Web services composition.