Current shared file systems (NFS and SAMBA) are based on the local area network model. To these file systems, performance is the major issue. However, as the Internet grows, so does the distance between users and the Local Area Network. With this increase in distance, the latency increases as well. This creates a problem when multiple users attempt to work in a shared environment. Traditionally, the only way to collaborate over the Internet required the use of locks. These requirements motivated the creation of the State Difference Transformation algorithm that allows users non-blocking and unconstrained interaction across the Internet on a tree based structure. Fine Grain Locking, on the other hand, allows a user the ability to set a lock on a character or range of characters while using a form of the transformation algorithm listed above. This thesis proposes an implementation that integrates these two technologies as well as demonstrating the effectiveness and flexibility of State Difference Transformation. The implementation includes two applications that can be used to further research in both the transformation and locking communities. The first application allows users to create tests for SDT and Fine Grain Locking and verify the correctness of the algorithms in any given situation. The second application then furthers this research by creating a real-world groupware interface to a shared file system based on a clientserver architecture. This implementation demonstrates the usability and robustness of these algorithms in real world situations.

Cloud-based collaborative editors enable real-time document processing via remote connections. Their common application is to allow Internet users to collaboratively work on their documents stored in the cloud, even if these users are physically a world apart. However, this convenience comes at a cost in terms of user privacy. Hence, the growth of popularity of cloud computing application stipulates the growth in importance of cloud security. A major concern with the cloud is who has access to user data. In order to address this issue, various third-party services offer encryption mechanisms for protection of the user data in the case of insider attacks or data leakage. However, these services often only encrypt data-at-rest, leaving the data which is being processed potentially vulnerable. The purpose of this study is to propose a prototype software system that encrypts collaboratively edited data in real-time, preserving the user experience similar to that of, e.g., Google Docs.

L'importance des systèmes collaboratifs a considérablement augmenté au cours des dernières années. La majorité de nouvelles applications sont conçues de manière distribuée pour répondre aux besoins du travail collaboratif. Parmi ces applications, nous nous intéressons aux éditeurs collaboratifs temps-réel (RCE) qui permettent la manipulation de divers objets partagés, tels que les pages wiki ou les articles scientifiques par plusieurs personnes réparties dans le temps et dans l'espace. Bien que ces applications sont de plus en plus utilisées dans de nombreux domaines, l'absence d'un modèle de contrôle d'accès adéquat limite l'exploitation de leur plein potentiel. En effet, contrôler les accès aux documents partagés de façon décentralisée et sans alourdir les performances du système collaboratif représente un vrai challenge, surtout que les droits d'accès peuvent changer fréquemment et de façon dynamique au cours du temps. Dans cette thèse, nous proposons un modèle de contrôle d'accès générique basé sur l'approche de réplication optimiste du document partagé ainsi que sa politique de contrôle d'accès. Pour cela, nous proposons une approche optimiste de contrôle d'accès dans la mesure où un utilisateur peut violer temporairement la politique de sécurité. Pour assurer la convergence, nous faisons recours à l'annulation sélective pour éliminer l'effet des mises à jour illégales. Vu l'absence d'une solution d'annulation générique et correcte, nous proposons une étude théorique du problème d'annulation et nous concevons une solution générique basée sur une nouvelle sémantique de l'opération identité. Afin de valider notre approche tous nos algorithmes ont été implémentés en Java et testés sur la plateforme distribuée Grid'5000 / The importance of collaborative systems in real-world applications has grown significantly over the recent years. The majority of new applications are designed in a distributed fashion to meet collaborative work requirements. Among these applications, we focus on Real-Time Collaborative Editors (RCE) that provide computer support for modifying simultaneously shared documents, such as articles, wiki pages and programming source code by dispersed users. Although such applications are more and more used into many fields, the lack of an adequate access control concept is still limiting their full potential. In fact, controlling access in a decentralized fashion for such systems is a challenging problem, as they need dynamic access changes and low latency access to shared documents. In this thesis, we propose a generic access control model based on replicating the shared document and its authorization policy at the local memory of each user. We consider the propagation of authorizations and their interactions. We propose a optimistic approach to enforce access control in existing collaborative editing solutions in the sense that a user can temporarily violate the access control policy. To enforce the policy, we resort to the selective undo approach in order to eliminate the effect of illegal document updates. Since, the safe undo is an open issue in collaborative applications. We investigate a theoretical study of the undo problem and propose a generic solution for selectively undoing operations. Finally, we apply our framework on a collaboration prototype and measure its performance in the distributed grid GRID?5000 to highlight the scalability of our solution

The thesis deals with methods of real-time data synchronization among multiple clients. The thesis focuses on methods in collaborative RIA systems running on the Internet This methods solve data transfer and conflict resolution caused by competitive clients work on one document. The introduction describes two methods: an established Operational transformation method and the new Differential synchronization method. The thesis describes the principles of both methods and their advantages and disadvantages. The aim of the work is implementing and comparison of Differential Synchronization method with Operational transformation method. These methods are compared in Node.js environment of JavaScript programming language and it is compared their performance in terms of response time and resource requirements. It's identified a problems associated with the method implementations in Node.js and it is described solutions of this problems. In the practical part thesis focus on the describing of performance data and behave of methods during measurement and refuted or confirmed the premises of methods definition assumptions. The Differential Synchronization method is extended by some parts based on the author often criticized issues of method.

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Real-time collaboration editing is research area that has been studied for over 20 years. It involves multiple users editing a document such as plain-text, rich-text or an image concurrently over a high-latency network. Many problems involving consistency between users are associated with concurrent document editing, and an innovative technique called Operational Transformation developed by the GROVE (GRoup Outline Viewing Editor) system in 1989 addresses some of these issues. This paper will compare and contrast current implementations of real-time collaborative editors, and on the basis of this analysis describe the creation of a new web-based editor with support for concurrent editing. The design of our web editor will focus on methods of mutual communication between the individual instances of the editors, propagation of text changes, how to solve conflicts between multiple operations, and communication failures.

Les éditeurs collaboratifs permettent à des utilisateurs éloignés de collaborer à une tâche commune qui va de l'utilisation d'un agenda partagé à la réalisation de logiciels. Ce concept est né avec SCCS en1972 et connait un engouement récent (ex: Wikipedia). L'absence de centralisation et l'asynchronisme sont des aspects essentiels de cette approche qui relève d'un modèle pair-à-pair (P2P).  D'un autre côté,le format XML est devenu une référence pour la manipulation et l'échange de documents. Notre travail vise à la réalisation d'un éditeur collaboratif P2P pour l'édition de documents semi-structurés qui sont une abstraction du format XML.  Le problème est difficile et de nombreuses propositions se sont révélées erronées ou ne passant pas à l'échelle. Nous rappelons les concepts et l'état de l'art sur l'édition collaborative, les modèles centralisés et le P2P.  Ensuite, nous explorons deux approches différentes : les transformées opérationnelles et le CRDT (Commutative Replicated Data Type) avec différentes structures de données arborescentes. L'objectif est de réaliser les opérations de base (ajout, suppression et ré-étiquetage) tout en garantissant la convergence du processus d'édition. Nous proposons un algorithme générique pour l'approche CRDT basée sur une notion d'indépendance dans la structure de données.  Nous avons étendu nos travaux afin de réaliser l'opération de déplacement d'un sous-arbre et de prendre en compte le typage XML. Peu de travaux abordent ces deux points qui sont très utiles pour l'édition de documents. Finalement, nous donnons les résultats expérimentaux obtenus avec un prototype permettant de valider notre approche. / Collaborative editors allow different users to work together on a common task. Such tasks range from using a shared calendar to realizing software programmed by users located at distant sites. This concept was invented in 1972 with SCCS. In the last years, this paradigm became popular (ex. Wikipedia). Decentralization and asynchronicity are essential in this approach, leading to peer-to-peer (P2P) models. Meanwhile, the XML format has arrived as the de facto standard for editing and exchanging documents. Our work aims at defining a collaborative editor for semi-structured documents, which provide an abstraction of the XML format. The problem is difficult since many previous approaches are flawed or not scalable. Firstly,we describe the basic concepts on collaborative edition and network models and we give the state of the art of this topic. Then, we investigate two different approaches : the operational transformation(OT) approach and the Commutative Replicated Data Type (CRDT) approach for different (tree-like) data structures. Our goal is to ensure the convergence of the editing process with the basic operations (Add, Deland rename a node. We have proposed a new generic algorithm based on semantic independence in data structure for CRDT approach. We have extended our results by dealing with the operation that moves a subtree and with XML schema compliance. Few works have been devoted to these extensions which are useful in collaborative edition. Finally, we provide experimental results obtained from our implementation that validate our approach.