Synchronizing data stream processing

Synchronization of data stream processing has a significant impact on performance of systems where processing of long sequences of data items needs to be done simultaneously. In earlier works on stream processing, synchronization has been discussed to a limited extent or has been completely overlooked. This work describes a formal model of synchronization in a data stream processing network. We use a notation of data stream processing networks to identify circumstances that necessitate synchronization. We also express processing of groups of data items in terms of database transactions within a data stream processing network. A technique similar to timestamp ordering of database transactions is used to solve the problems. A solution is presented as a set of rules that govern processing of groups of data items. A proof of correctness has been provided for the strategy used to solve the problems.