Data Consistency for P2P Collaborative Editing

http://portal.acm.org/Peer-to-peer (P2P) networks are very efficient for distributing content. We want to use this potential to allow not only distribution but collaborative editing of this content. Existing collaborative editing systems are centralised or depend on the number of sites. such systems cannot scale when deployed on P2P networks. In this paper, we propose a new model for building a collaborative editing system. This model is fully decentralised and does not depend on the number of sites

Proving Correctness of Transformation Functions in Real-Time Groupware

Colloque avec actes et comité de lecture. internationale.International audienceOperational transformation is an approach which allows to build real-time groupware tools. This approach requires correct transformation functions. Proving the correction of these transformation functions is very complex and error prone. In this paper, we show how a theorem prover can address this serious bottleneck. To validate our approach, we have verified the correctness of state-of-art transformation functions defined on Strings with surprising results. Counter-examples provided by the theorem prover have helped us to define new correct transformation functions for Strings

Towards Synchronizing Linear Collaborative Objects with Operation Transformation

A collaborative object represents a data type (such as a text document or a filesystem) designed to be shared by multiple geographi- cally separated users. Data replication is a technology to improve perfor- mance and availability of data in distributed systems. Indeed, each user has a local copy of the shared objects, upon which he may perform up- dates. Locally executed updates are then transmitted to the other users. This replication potentially leads, however, to divergent (i.e. different) copies. In this respect, Operational Transformation (OT) algorithms are applied for achieving convergence of all copies, i.e. all users view the same objects. Using these algorithms users can apply the same set of updates but possibly in different orders since the convergence should be ensured in all cases. However, achieving convergence with the OT approach is still a critical and challenging issue. In this paper, we address an open convergence problem when the shared data has a linear structure such as list, text, ordered XML tree, etc. We analyze the source of this problem and we propose a generic solution with its formal correctness

Real time group editors without Operational transformation

A real time group editor allows multiple users to edit the same text at the same time from multiple sites across Internet. The real time group editors community has developed a framework called Operational Transformation (OT) for maintaining consistency of shared data. OT differs from other optimistic replication systems by not only ensuring content consistency but also intention consistency. In this paper, we describe the WOOT (WithOut Operational Transformation) framework that ensures intention consistency without following the OT approach. However, thanks to its new viewpoint, WOOT is drastically simpler, more efficient and does not require vector clocks or central sites. The WOOT framework is particularly adapted to very large peer-to-peer networks

Development of Transformation Functions Assisted by a Theorem Prover

Colloque sans acte à diffusion restreinte. internationale.International audienceTransformational approach requires to write transformation functions that ensure properties C1 and C2. Proving these conditions on complex typed objects is a serious bottleneck for the application of this approach. We propose to use a theorem prover to assist the development of safe transformation functions. In this paper, we present how we have designed in that way a set of safe transformation functions for an XML typed object

Achieving Convergence with Operational Transformation in Distributed Groupware Systems

Distributed groupware systems provide computer support for manipulating shared objects by dispersed users. Data replication is used in such systems in order to improve the availability of data. This potentially leads to divergent (or different) replicas. In this respect, the Operational Transformation (OT) approach is employed to maintain convergence of all replicas, all users view the same object. Using this approach, users can exchange their updates in any order since the convergence should be ensured in all cases. However, designing correct OT algorithms is still an open issue. In this paper, we demonstrate that recent OT algorithms are incorrect. We analyse the source of this problem and we propose a generic solution with its formal correctness

The Java Learning Machine: A Learning Management System Dedicated To Computer Science Education

This paper presents the Java Learning Machine (JLM), a platform dedicated to computer programming education. This generic platform offers support to teachers for creating programming microworlds suitable to teaching courses. It features an integrated and graphical environment, providing a short feedback loop to students in order to improve the effectiveness of the autonomous learning process. This paper presents the motivations behind the platform and its main functionalities.Ce rapport présente la Java Learning Machine (JLM), une plate-forme dédiée à l'enseignement de la programmation. Cette plate-forme générique permet aux enseignants d'informatique de créer des micro-mondes utilisables dans leurs cours. Elle constitue un environnement graphique intégré, offrant aux apprenants d'obtenir un retour immédiat sur leur travail. Cela permet d'améliorer l'efficacité du processus d'apprentissage en autonomie. Ce rapport présente les motivations ayant mené à la création de la plate-forme, ainsi que les principales fonctionnalités de l'outil

Safe Generic Data Synchronizer

Rapport interne.Reconciliating divergent data is an important issue in concurrent engineering, mobile computing and software configuration management. Actually, a lot of synchronizers or merge tools perform reconciliations, however, which strategy they apply ? is it correct ? In this paper, we propose to use a transformational approach to build a safe generic data synchronizer

Peer-to-peer Collaboration over XML Documents

International audienceExisting solutions for the collaboration over XML documents are limited to a centralised architecture. In this paper we propose an approach for peer-to-peer collaboration over XML documents where users can work off-line on their document replica and synchronise in an ad-hoc manner with other users. Our algorithm for maintaining consistency over XML documents recursively applies the tombstone operational transformation approach over the document levels

Optimistic Replication for Massive Collaborative Editing

In recent times, Wikipedia has opened the way to massive collaborative editing. More specifically, it has demonstrated what can be achieved with a massive collaborative effort. Massive collaborative editing implies scalability and pessimistic replication scales poorly in the wide area. Optimistic replication offers better performance but has severe drawbacks for maintaining consistency. In this paper, we propose a new optimistic replication algorithm for massive collaborative editing called WOOT. It is designed to scale as well as to ensure eventual consistency and intention preservation. It is important to point out that WOOT's efficiency does not depend on a number of sites and can be deployed on a very large, pure peer-to-peer network