Mobile data sharing and high availability

This work introduces a model for decentralised and platform-independent data sharing for highly dynamic networks. The goal is not to deliver a solution that can be considered similar to database systems. Communication and replication challenges are presented and examined from the perspective of nomadic computing. The aim has been to provide highly available data sharing over features over mobile distributed systems. The primary functionality of the data-sharing model introduced here has been validated with simulations. A fully functional data-sharing model has been implemented and tested in a simulated environment. A simulated environment was chosen over real network conditions in order to offer data distribution pattern tracking in several different network topologies and environments. This study provides understanding of the data sharing factors that are important in decentralised distribution models. These factors include location determination for replica storing and control message propagation over weak connections. Smart data distribution is crucial for weakly connected networks to offer access to shared resources. In heterogeneous environments, it is also necessary to consider possible transmission resource savings, and an idea for partitioning data into small elements is introduced. A data distribution algorithm based on this understanding is designed and evaluated. According to technology surveys and the evaluation of data sharing implementation, it is clear that the optimistic replication schema is the choice for data distribution over weakly connected networks. This requires conflict solving for eventual consistency, or any equivalent method to provide the correct operation for applications. A decentralised data management model is the best alternative to operate in weakly connected networks, as it is able to function regardless of network partitions. The data sharing approach presented here provides full adaptability to different network topologies and computing platforms, and it is able to offer data sharing services for any device to some degree. A decentralised data sharing approach introduces new challenges; these are discussed, and their viability for implementation is estimated.