Nous introduisons la stratégie de réécriture de termes k-bornée (bo(k), pour k entier) pour les systèmes linéaires. Cette stratégie est associée à une classe de systèmes dits k-bornés LBO(k). Nous démontrons que les systèmes de la classe LBO (union des LBO(k) pour tous les k), inversent-préservent la reconnaissabilité. Nous montrons que les différents problèmes de terminaison et d'inverse-terminaison pour la stratégie bo(k) sont décidables et utilisons ce résultat pour démontrer la décidabilité de ces problèmes pour des sous-classes de LBO: les classes de systèmes linéaires fortement k-bornés: LFBO(k). La classe LFBO (union des LFBO(k)) inclut strictement de nombreuses classes de systèmes connues: les systèmes inverses basiques à gauche, linéaires growing, et linéaires inverses Finite-Path-Overlapping. Le problème de l'appartenance à LFBO(k) est décidable alors qu'il ne l'est pas pour LBO(0). Pour les mots, nous prouvons que la stratégie bo(k) préserve l'algébricité. Nous étendons la notion de réécriture k-bornée aux systèmes de réécriture de termes linéaires à gauche. Comme dans le cas linéaire, nous associons à cette stratégie la classe des systèmes linéaires à gauche k-bornés BO(k) qui étend la classe LBO(k). Nous démontrons que les systèmes de cette classe inverse-préservent la reconnaissabilité.Comme dans le cas linéaire, nous définissons ensuite la classe des systèmes fortement kbornés FBO(k), qui étend la classe LFBO(k). Nous montrons que le problème de l'appartenance à FBO(k) est décidable. La classe FBO contient strictement la classe des systèmes growing linéaires à gauche. / We introduce k-bounded term rewriting for linear systems (bo(k), for k integer). This strategy is associated with the class of k-bounded systems LBO(k). We show that the systems in the class LBO (union of the LBO(k) for all k), inverse-preserve recognizability. We show that the problems of termination and inverse-termination for the bo(k) strategy are decidable and use this result to show the decidability of these two problems for subclasses of LBO: the classes of linear systems strongly k-bounded: LFBO(k). The class LFBO (union of the LFBO(k)) includes strictly many known classes: the inverse left-basic systems, the linear growing systems, the linear inverse Finite-Path-Overlapping systems. Membership to LFBO(k) is decidable but this is not hte case for LBO(0). For words, we show that the bo(k) strategy preserves algebricity. We extend k-bounded rewriting to left-linear systems. As in the linear case, we associate a class of systems to the strategy: the class of left-linear kbounded systems BO(k) which extends LBO(k). We show that the systems in BO(k) inversepreserve recognizability. As in the linear case, we define the class of strongly k-bounded systems FBO(k), which extends LFBO(k). Membership to FBO(k) is proved decidable. The FBO class contains stricly the class of left-linear growing systems.

We present a term rewriting procedure based on congruence closure that can be used with arbitrary equational theories. This procedure is motivated by the pragmatic need to prove equations in equational theories where confluence can not be achieved. The procedure uses context free grammars to represent equivalence classes of terms. The procedure rewrites grammars rather than terms and uses congruence closure to maintain certain congruence properties of the grammar. Grammars provide concise representations of large term sets. Infinite term sets can be represented with finite grammars and exponentially large term sets can be represented with linear sized grammars.

雲端運算環境的興起，軟體即服務(Software as a Service, SaaS)的營運模式也開始受到軟體開發商的注意，其中一項關鍵技術是支援多租戶的軟體開發。在設計多租戶應用程式時有許多需要考量的因素，包含每個租戶各自的客製化設定、資料安全性等等。本論文著重於資料層級的客製化部份，如何讓各個租戶之間可以共用資料庫，但又能提供租戶適度地更改其資料表綱要(schema)以達到客製化的需求。 為了解決資料層級客製化所面臨的問題，一種常見的作法是可延伸性表格(Extension Table Layout)。但是，在關聯式資料庫中實作可延伸性表格，軟體開發人員為了配合可延伸性表格的資料存放方式，所使用的SQL語句會變得相當複雜且易錯。因此，本研究實作一個系統工具協助軟體開發人員將SQL語句，從一租戶一資料表寫法自動轉換成以可延伸性表格邏輯表達的SQL語句，透過執行轉換後的語句來對儲存在可延伸性表格的資料進行增刪修改。 軟體開發人員在本系統工具的協助下，加入租戶識別碼(TenanId)的開發概念後，即可實際建立一個多租戶應用程式。為了評估本系統工具的效用，我們以其建置了一個多校(租戶)選課系統，並進行多項效能實驗以探討影響本系統工具效能的因素。初步的結果顯示，本系統工具可以協助軟體開發人員，以較低的代價滿足資料層級客製化應用的需求。 / Software as a service (SaaS) is an emerging service model of cloud computing. One of the key technology in SaaS is supporting multi-tenant applications. There are many considerations in the design of multi-tenant applications, including customized configuration of tenants and data security. In this thesis, we focus on data-level customized configuration, and propose an approach for not only sharing database between tenants but also supporting tenants to modify their table schemas within limits. Extension Table Layout is one solution for solving the problems in data-level customized configuration for multi-tenant applications. However, SQL statemenst based on the Extension Table Layout are rather complicated and error-prone. Thus, we develop a tool to help software developers that will automatically rewrite the SQL statements from the common Private Table Layout into those from the Extension Table Layout at runtime. In other words, our tool enable software developers to write SQL statements in a multi-tenant application like in a single tenant application. Indeed, software developers could develop a multi-tenant application easily by using our tool and the multi-tenant enabler - TenantId. In order to assess the feasibility of our tool, we develop an online multi-tenant course election application. Besides, we disscus the effectiveness of the factors that affecting our tool and work on a number of experiments and performance tests. The preliminary results show that our SQL rewriting tool can help software developers at a lower cost to meet the needs of data-level customized applications to a degree.

With the constant proliferation of information systems around the globe, the need for decentralized and scalable data sharing mechanisms has become a major factor of integration in a wide range of applications. Literature on information integration across autonomous entities has tacitly assumed that the data of each party can be revealed and shared to other parties. A lot of research, concerning the management of heterogeneous sources and database integration, has been proposed, for example based on centralized or distributed mediators that control access to data managed by different parties. On the other hand, real life data sharing scenarios in many application domains like healthcare, e-commerce market, e-government show that data integration and sharing are often hampered by legitimate and widespread data privacy and security concerns. Thus, protecting the individual data may be a prerequisite for organizations to share their data in open environments such as Internet. Work undertaken in this thesis aims to ensure security and privacy requirements of software systems, which take the form of web services, using query rewriting principles. The user query (SPARQL query) is rewritten in such a way that only authorized data are returned with respect to some confidentiality and privacy preferences policy. Moreover, the rewriting algorithm is instrumented by an access control model (OrBAC) for confidentiality constraints and a privacy-aware model (PrivOrBAC) for privacy constraints. A secure and privacy-preserving execution model for data services is then defined. Our model exploits the services¿ semantics to allow service providers to enforce locally their privacy and security policies without changing the implementation of their data services i.e., data services are considered as black boxes. We integrate our model to the architecture of Axis 2.0 and evaluate its efficiency in the healthcare application domain.

Biological data is accumulated at a fast pace. However, raw data are generally difficult to understand and not useful unless we unlock the information hidden in the data. Knowledge/information can be extracted as the patterns or features buried within the data. Thus data mining, aims at uncovering underlying rules, relationships, and patterns in data, has emerged as one of the most exciting fields in computational science. In this dissertation, we develop efficient approaches to the structure pattern analysis of RNA and protein three dimensional structures. The major techniques used in this work include term rewriting and clustering algorithms. Firstly, a new approach is designed to study the interaction of RNA secondary structures motifs using the concept of term rewriting. Secondly, an improved K-means clustering algorithm is proposed to estimate the number of clusters in data. A new distance descriptor is introduced for the appropriate representation of three dimensional structure segments of RNA and protein three dimensional structures. The experimental results show the improvements in the determination of the number of clusters in data, evaluation of RNA structure similarity, RNA structure database search, and better understanding of the protein sequence-structure correspondence.

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