臺灣博碩士論文加值系統

隨著網路的蓬勃發展，服務導向架構變成一種新的程式開發技術，隨著愈來愈多的網路服務被佈署在網路上，程式開發者可以選擇最合適的網路服務來實作出最符合本身要求的應用程式。但是隨著網路服務的增加，使用者必需不斷的在網路上搜尋所需的服務，光是查尋就是一件很費時的工作。另外，每個服務通常會用一些額外的屬性來描述本身的QoS，而不同的服務通常就會有不同的QoS，要從眾多的選擇中挑選可以符合使用者要求的服務品質的服務更是一件不容易的事情。
在本文中，我們改良原先網路服務的架構，提出一個可以減輕使用者負擔的UDDI系統。其中的Inter-Communication Module會將使用者的查尋要求傳送到網路上的其他UDDI系統，可以避免使用者在不同的UDDI中來回查尋所花的時間，進而達到分散式系統中的透通性。當使用者透過UDDI獲得網路上不同的服務之後，並不是所有的合成結果都會滿足使用者的預期，使用者仍需花時間來判斷那些服務可以提供可接受的服務品質。因此，系統中的Composition Analyzer Module藉由NSGA-II演算法來分析從網路上查尋而得的服務，用來找出所有滿足限制條件且可把多個目標最佳化的可行解。最後實驗結果用來顯示使用NSGA-II演算法來找出最佳解的可行性。

As more and more web services appearing on the Internet, how to locate an appropriate service has become
a research challenge and an emerging enterprise request. In this paper, we present a transparent web service
acquisition system by enhancing the functionality of UDDI to support various service requirements.
With this system, a service requester can transparently locate a service which meets multiple objectives.
As UDDI having been taken as the registry standard for both register and query of web services, our approach
is to deal with service composition processing in UDDI and to allow inter-UDDI communications.
With the employment of the NSGA-II algorithm, we are able to find out the feasible service compositions
which satisfy both cost and time constraints with maximized reliability and availability.
An experiment was carried out to demonstrate the feasibility of executing the NSGA-II algorithm in
obtaining the optimal service compositions.

1. Introduction 1
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Motivation and Objectives . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3. Thesis Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Related Work 3
2.1. Web Services Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1. SOAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.2. WSDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.3. UDDI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Service Selection Algorithms . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.1. Service Composition . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.2. QoS Issues in Web Services and Composition Service . . . . . 7
2.2.3. Selection Algorithm with Single QoS Constraint . . . . . . . . 8
2.2.4. Selection Algorithm with Multiple QoS Constraints . . . . . . 10
2.3. Genetic Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.1. Basic Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.2. Basic Operators of Genetic Algorithms . . . . . . . . . . . . . 11
3. An Enhanced Web Service Access System 14
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2. Propagation Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.1. Basic Idea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.2. Actions for Query Requests . . . . . . . . . . . . . . . . . . . 14
3.3. Multiobjective QoS Constraints . . . . . . . . . . . . . . . . . . . . . 16
3.3.1. Composition Analysis Problem Specification . . . . . . . . . . 17
3.3.2. Adopting NSGA-II for Composition Analysis Problem . . . . 18
3.4. System Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4.1. Standard UDDI Server . . . . . . . . . . . . . . . . . . . . . . 20
3.4.2. User Query Interface Module . . . . . . . . . . . . . . . . . . 20
3.4.3. Inter-UDDI Communication Module . . . . . . . . . . . . . . 20
3.4.4. Composition Analyzer Module . . . . . . . . . . . . . . . . . . 22
4. Implementation Details and Demonstrations 26
4.1. Experimentation Environment . . . . . . . . . . . . . . . . . . . . . . 26
4.2. System Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.2.1. User Query Interface Module . . . . . . . . . . . . . . . . . . 26
4.2.2. Standard UDDI Server . . . . . . . . . . . . . . . . . . . . . . 29
4.2.3. Composition Analyzer Module . . . . . . . . . . . . . . . . . . 29
4.2.4. Inter-UDDI Communication Module . . . . . . . . . . . . . . 29
4.3. Demonstration of Propagation Protocol . . . . . . . . . . . . . . . . . 30
4.3.1. Infinite Loop and Duplication Request Avoidance . . . . . . . 32
4.3.2. Dynamic Configuration . . . . . . . . . . . . . . . . . . . . . . 32
4.4. Results of Service Selection . . . . . . . . . . . . . . . . . . . . . . . 36
5. Conclusions 40
5.1. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.2. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
References 42

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