FEW phone file system

Trabalho apresentado no âmbito do Mestrado em Engenharia Informática, como requisito parcial para obtenção do grau de Mestre em Engenharia InformáticaThe evolution of mobile phones has made these devices more than just simple mobile communication devices. Current mobile phones include such features as built-in digital cameras, the ability to play and record multimedia contents and also the possibility of playing games. Most of these devices have support for Java developed applications, as well as multiple wireless technologies (e.g. GSM/GPRS, UMTS, Bluetooth, and Wi-Fi). All these features have been made possible due to technological evolution that led to the improvement of computational power, storage capacity, and communication capabilities of these devices. This thesis presents a distributed data management system, based on optimistic replication,named FEW Phone File System. This system takes advantage of the storage capacity and wireless communication capabilities of current mobile phones, by allowing users to carry their personal data “in” their mobile phones, and to access it in any workstation, as if they were files in the local file system. The FEW Phone File System is based on a hybrid architecture that merges the client/server model with peer-to-peer replication, that relies on periodic reconciliation to maintain consistency between replicas. The system’s server side runs on the mobile phone, and the client on a workstation. The communication between the client and the server can be supported by one of multiple network technologies, allowing the FEW Phone File System to dynamically adapt to the available network connectivity. The presented system addresses the mobile phone’s storage and power limitations by allowing multimedia contents to be adapted to the device’s specifications, thus reducing the volume of data transferred to the mobile phone, allowing for more user’s data to be stored. The FEW Phone File System also integrates mechanisms that maintain information about the existence of other copies of the stored files (e.g. WWW), avoiding the transfer of those files from the mobile device whenever accessing those copies is advantageous. Due to the increasing number of on-line storage resources (e.g. CVS/SVN, Picasa), this approach allows for those resources to be used by the FEW Phone File System to obtain the stored copies of the user’s files

Tinzenite: Encrypted Peer to Peer File Synchronization via the Tox Protocol

We proposed and implemented an open source, peer to peer, file synchronization software based on the Tox communication protocol. Targeted features include full secure communication between peers, an encrypted server peer, and a focus on ease of use while retaining data security. The software suite was implemented based on the Tox protocol, with Golang as the programming language, and the server client built to offer free choice of storage mechanisms, for which we implemented support for the Hadoop distributed file system. The proof of concept implementation was shown to work and further possible work discussed

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

Network Synchronization of Data under OS Windows

Tato práce se zabývá problémem návrhu a implementace nástroje pro synchronizaci souborů v síťovém prostředí pro OS Windows. Je poukázáno na problémy, které se při synchronizaci mohou vyskytnout, jako například správná detekce konfliktních změn, a jejich řešení. Dále je přiblížen problém ustanovení přímého spojení mezi dvěma zařízeními v internetu, pokud jsou tato zařízení k internetu připojena prostřednictvím zařízení NAT. V práci je ukázána konkrétní implementace řešení konfliktů, detekovaných během synchronizace, a aplikace některých metod pro překonávání zařízení NAT. Testováním byla ověřena funkčnost části výsledného nástroje pro řešení konfliktů a překonávání NAT. V závěru jsou diskutovány výsledky testování a navrhnuty možná rozšíření.This thesis deals with an implementation of a tool for file synchronization over a network for OS Windows. It also illustrates what issues are associated with synchronization of files, such as collision detection and resolution and the issue of setting up connection between two devices over the internet when connected to the internet via NAT devices. Thesis presents factual implementation of collision resolver and application of methods for NAT traversal. By testing the final solution correctness of collision resolver and NAT traversal technique was verified. Results of testing are discussed and possible extensions are proposed.

XWiki Concerto: A P2P Wiki System Supporting Disconnected Work

International audienceThis paper presents the XWiki Concerto system, the P2P version of the XWiki server. This system is based on replicating wiki pages on a network of wiki servers. The approach, based on the Woot algorithm, has been designed to be scalable, to support the dynamic aspect of P2P networks and network partitions. These characteristics make our system capable of supporting disconnected edition and sub-groups, making it very flexible and usable

What\u27s in Unison? A Formal Specification and Reference Implementation of a File Synchronizer

A file synchronizer is a tool that reconciles disconnected modifications to a replicated directory structure. Trustworthy synchronizers are difficult to build, since they must deal correctly with both the semantic complexities of file systems and the unpredictable failure modes arising from distributed operation. On the other hand, synchronizers are often packaged as stand-alone, user-level utilities, whose intended behavior is relatively easy to isolate from the other functions of the system. This combination of subtlety and isolability makes file synchronizers attractive candidates for precise mathematical specification. We present here a detailed specification of a particular file synchronizer called Unison, sketch an idealized reference implementation of our specification, and discuss the relation between our idealized implementation and the actual code base

Communication Timestamps for File System Synchronization

The problem of detecting various kinds of update conflicts in file system synchronization following a network partition is well-known. All systems of which we are aware use the version vectors of Parker et al. These require O(R*F) storage space for F files shared among R replicas. We propose a number of different methods, the most space-efficient of which uses O(R*F) space in the worst case, but O(R+F) in the expected case. To gain experience with the various methods, we implemented a file synchronization tool called Tra. Based on this experience, we discuss the advantages and disadvantages of each particular method. Tra itself turns out to be useful for a variety of tasks, including home directory maintenance, operating system installation, and managing offline work. We discuss some of these uses.Engineering and Applied Science

Bidirectionally Tolerating Inconsistency: Partial Transformations

Abstract. A foundational property of bidirectional transformations is that they should be correct: that is, the transformation should succeed in restoring consistency between any models it is given. In practice, how-ever, transformation engines sometimes fail to restore consistency, e.g. because there is no consistent model to return, or because the tool is unable to select a best model to return from among equally good candi-dates. In this paper, we formalise properties that may nevertheless hold in such circumstances and discuss relationships and implications.