智慧家庭中的情境感知普及服務管理機制

Abstract

智慧家庭主要的願景為透過科技使人們的日常生活更加豐富。此一類型的智慧居住空間具備推測居住者意向並據以提供適切智慧居家服務的能力。大部份的智慧居家服務都由許多高異質性的元件所組成。本論文主要的研究目標即在於設計一組服務管理機制，使得智慧居家服務能夠具備高彈性、強健性、高效能及一致性的特色。 首先，系統的彈性與否大部份取決於其底層之架構型式(Architectural Style)，在比較過相關系統與文獻之後可發現訊息導向中介軟體架構(Message-Oriented Middleware, MOM)是最具備彈性且適合佈署於家庭網路之架構型式。在另一方面，雖然許多文獻都指出強健性為智慧家庭系統不可或缺之一環，但可發現在現存研究中對於加強訊息導向架構系統強健性著墨較少。因此，本論文提出一個兼具彈性與強健性的服務管理架構。本研究以嚴謹的正規程序代數(Process Algebra)的方式定義了一個可支援自主型組合、錯誤偵測及錯誤回復之訊息導向服務模型與其通訊協定，並對此一服務模型與協定進行強健性的正規驗證及實際的回復率與效能測試實驗。 其次，在智慧家庭中，無目錄式服務管理協定(如通用型隨插即用協定)被認為是較為適合管理智慧家庭服務的機制。此類協定大都以IP群播加以實現，但經常造成網路擁塞的問題。因此，基於前述之訊息導向服務模型，本研究提出一套可有效降低冗餘封包數量，進而提昇網路效能的機制來改善無目錄式服務管理協定所造成之網路擁塞的問題。經過分析與網路模擬實驗，可發現二者之間具有相當高的一致性，且均具備大幅提昇網路效能的效果。 近年來，有不少研究著重於普及服務的組合議題。在組合普及服務之前，使用者必須先行提出偏好(Preference)，但使用者之偏好不確定性高且可能彼此衝突。由於居家環境經當變動，也很可能造成所啟動之服務之間的相互衝突。為了解決這些問題，本研究提出一組可同時表達列舉/可數及必要/可商議概念之偏好表示式(Preference Expression)。此一機制配合本研究所發展之一套可驗證的邏輯結合規則(Unification Rules)，可將不一致的使用者偏好表示式整合為一致的表示式。接下來並提出一套以模糊邏輯為基礎的方法，基於環境式情境資訊，評估已啟動服務間相互衝突之嚴重程度。經過實驗可發現，藉由整合上述機制，可同時維持相當高的服務組合之品質及成功率。 最後，本研究整合上述機制進行實作，並實際將多個智慧居家服務佈署於二個不同智慧實驗屋，以驗證所提出之各項機制之可行性。

The concept of Smart Home envisions a technology-enriched living space that is capable of anticipating intensions of occupants and providing appropriate services accordingly. Most of the services in such space are context-aware and are realized by an assemblage of heterogeneous components. The objective of this thesis is to design a suite of service management mechanisms that makes such context-aware services flexible, robust, efficient, and consistent. The flexibility heavily depends on the underlying architecture style. After a thorough review on existing representative pervasive systems, it is concluded that the Message-Oriented Middleware (MOM) is one of the most flexible architecture styles for the Smart Home. Meanwhile, robustness is one of the key challenges for the Smart Home, but few researches have been done to improve the robustness of Message-Oriented Smart Home systems. Hence, this research work attempts to propose a flexible and robust service management framework by formally defining an MOM-based service application model and protocols that facilitate autonomous composition, failure detection and recovery of services. The proposed approach is evaluated by first proving the reliability property and then conducting experiments on recovery rate as well as performance. Decentralized service management protocols such as UPnP are believed to be more suitable for Smart Homes. These protocols are usually realized by using IP multicast, which, if not carefully designed, often suffer from network flooding problems. This research proposes several efficiency boosting techniques that reduce the replications of unnecessary messages. The analytical predictions agree well with the simulated and experimental results, which show that the traffic can be greatly reduced by the proposed approaches. Pervasive service composition also attracts increasing interests. When composing services, the criteria for scoring and electing services are usually specified by users, which tend to be vague and subjective. Moreover, the deployment of services in smart homes is usually not as well-planned as that in traditional enterprise environments. Hence, the criteria can be contradictory and the activated components can interfere with one another. This thesis addresses these issues by first proposing the Preference Expression that is capable of specifying both enumerative/numeric as well as mandatory/negotiable preferences. Then, a set of unification rules for unifying conflicting preferences is presented. Finally, this thesis proposes a Fuzzy-based approach to estimate the degree of interference based on available context information. By incorporating the above-mentioned mechanisms, an integrated service composition framework is presented. Experiments that evaluate the effectiveness of the proposed framework are also conducted and reported.