Contributions to efficiency of total order broadcast protocols and to RFID-based delay tolerant networks
In asynchronous distributed systems, logical clock and vector clocks are two core tools to manage data communication and data sharing between entities of these systems. The goal of this PhD thesis is to exploit these tools with a coding viewpoint. In the first part of this thesis, we focus on data communication and contribute to the total order broadcast domain. We propose trains protocol: Tokens (called trains) rotate in parallel between participating processes distributed on a virtual ring. Each train contains a logical clock to recover lost train(s) in case of process(es) failure. We prove that trains protocol is a uniform and totally ordered broadcast protocol. Afterwards, we create a new metric: the throughput efficiency. With this metric, we are able to prove that, from a throughput point of view, trains protocol performs better than protocols presented in literature. Moreover, this metric gives the maximal theoretical throughput which can be reached when coding a given protocol. Thus, it is possible to evaluate the quality of the coding of a protocol. Thanks to its throughput performances, in particular for small messages, trains protocol is a remarkable candidate for data sharing between the cores of a processor. Moreover, thanks to its temperance concerning network usage, it can be worthwhile for data replication between servers in the cloud. Part of this work was implemented inside a control-command and supervision system deployed among several dozens of industrial sites. In the second part of this thesis, we focus on data sharing and contribute to RFID domain. We propose a distributed shared memory based on RFID tags. Thanks to this memory, we can avoid installing a computerized global network. This is possible because this memory uses vector clocks and relies on the network made by the mobile users of the distributed application. Thus, the users are able to read the contents of remote RFID tags. Our RFID-based distributed shared memory is an alternative to the three RFID-based architectures available in the literature. This distributed shared memory was implemented in a pervasive game tested by one thousand users.