José Ramón González de Mendívil

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Database replication protocols need to detect, block or abort part of conflicting transactions. A possible solution is to check their writesets (and also their readsets in case a serialisable isolation level is requested), which however burdens the consumption of CPU time. This gets even worse when the replication support is provided by a middleware, since(More)
Database replication is a way to increase system performance and fault-tolerance of a given system. The price to pay is the effort needed to guarantee data consistency, and this is not an easy task. In this paper, we introduce a description of two 1-Copy-Serializable (1CS) [1] eager update everywhere replication protocols. The preliminary results of their(More)
This paper describes user location and tracking on indoor scenarios through a wireless network. We propose a fuzzy location algorithm, using fuzzy inference systems, in order to deal with imprecise location based on radio-frequency trilateration estimations, providing high location rates near to 90. This indoor positioning approach is based on the pattern(More)
Database replication has been researched as a solution to overcome the problems of performance and availability of distributed systems. Full database replication, based on group communication systems, is an attempt to enhance performance that works well for a reduced number of sites. If application locality is taken into consideration, partial replication,(More)
Several previous works have proven that there is no way of guaranteeing a snapshot isolation level in symmetrical replicated database systems without blocking transactions when they are started. As a result of this, the generalized snapshot isolation (GSI) level was defined, relaxing a bit the freshness of the snapshot being taken when a transaction is(More)
— Data replication among different sites is viewed as a way to increase application performance and its data availability. In this paper, we propose an algorithm design for concurrency control and recovery in a middleware architecture called COPLA (Common Object Programmer Library Access). This architecture provides persistent object state replication. The(More)