Nec Corporation

Nec Europe Ltd.

Dan Dobre

Ghassan Karame

Wenting Li

Jens-Matthias Bohli

Marko Vukolić

Joao Girao

Nuno Filipe Vieira Dos Santos

Marko Vukolic

A method for replicating data in a cloud storage system supporting multiple clients, wherein the cloud storage system comprises a plurality of object storing entities (A, B, C) for storing data objects, includes requesting, by a client, values and associated timestamps for a first data object from a first quorum of the object storing entities (A, B, C). The method further includes determining, by the client, a most recent value of the first data object based on the associated timestamps. The method additionally includes performing, by the client, a compare-and-swap procedure, so that the determined value and its corresponding timestamp for the first data object updates the first data object with a value with a newer timestamp and stores the first data object in a second quorum of the object storing entities (A, B, C).

Method and system for replicating data in a cloud storage system

Methods and systems for storing a file on a plurality of servers are provided including a number of servers and a maximum number of servers which may fail. A predefined number of byzantine failures and a number of crashes of the servers is contemplated. The file is divided into a plurality of chunks, where the number of chunks is equal to or greater than the number of servers. The chunks of the file are sent to the servers, where at least one chunk is sent to each server. The number of replies from the servers indicating successful storage of the respective chunks are determined. The number of replies matching a terminating condition is checked. A new file is generated.

Method and system for storing a file on a plurality of servers

Methods and systems for storing a file on a plurality of servers are provided. The number of servers is n and the maximum number of servers which may fail is t. A predefined number b of byzantine failures and a number t&#x2212;b of crashes of the servers is contemplated, where n equals 2t+b+1. The file is divided into a plurality of chunks, where the number of chunks is equal to or greater than the number of servers. The chunks of the file are sent to the n servers, where at least one chunk is sent to each server. The number of replies r from the n servers indicating successful storage of the respective chunks are determined. The number of replies r matching a terminating condition is checked. A new file based is generated. The process is repeated for the new file.

A method for generating a dataset structure for location-based services includes partitioning a geographical area, including areas of interest, into tiles. The tiles are associated with servers, wherein each of the tiles is associated with at least one server based on a consistent hashing function. For each of the tiles, a first dataset is generated which includes the areas of interest intersecting the tile. The areas of interest of the first dataset are trimmed by edges of the tile or completely contained in the tile. For each of the tiles, a second dataset is generated which includes overflowed parts. Each of the overflowed parts is part of an areas of interest of the first dataset, is trimmed by an edge of the tile and is located outside of the tile. For each of the tiles, the first and second datasets are stored at the server(s) associated to the tile.

Method for generating a dataset structure for location-based services and method and system for providing location-based services to a mobile device

A method for preserving privacy within a communication system, wherein a location-based service concerning an area of interest is provided for at least one user by a database server and wherein location information represented by coordinates of objects and/or users and/or areas and/or queries, made to the location-based service, is concealed, includes concealing the location information by transforming coordinates by first splitting the area of interest up in tiles for providing at least one tiling of the area of interest, and then permuting the tiles by a pseudo-random permutation process.

Preserving privacy by concealing location information with a pseudo-random permutation process

A method for byzantine fault tolerant data replication with a plurality of 2f+1 data servers and one or more clients includes storing data in at least f+1 different data servers out of the 2f+1 data servers, and storing metadata of the stored data under a metadata-identifier in a metadata-service (MDS). The stored metadata includes a unique identifier of the stored data, a fingerprint of the stored data, and a list of the at least f+1 different data servers which have stored the data.

Method and system for byzantine fault tolerant data replication

A method is used to build a concurrent data structure in the form of a ranked register based on a Compare-And-Swap (CAS) functionality and an according ranked register, to allow reliable access of shared data within a storage by multiple clients. Read and write operations are defined within the ranked register. The read operation takes a rank as argument and returns a rank-value pair. The write operation takes a rank-value pair as argument and returns either commit or abort. The read operation returns a rank-value pair that was written in a previous write operation.

Method for building a ranked register and a compare-and-swap object, a ranked register and compare-and-swap-objects

A method and system for storing data in a key value storage having a plurality of n servers, wherein t&#x3c;n servers may fail arbitrarily and wherein 3t+1=n is satisfied, the method includes:

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Munich, Germany

Dan Dobre