Concurrent Model Synchronization with Conflict Resolution Based on Triple Graph Grammars

Triple graph grammars (TGGs) have been used successfully to analyse correctness of bidirectional model transformations. Recently, also a corresponding formal approach to model synchronization has been presented, where updates on a given domain (either source or target) can be correctly (forward or backward) propagated to the other model. However, a corresponding formal approach of concurrent model synchronization, where a source and a target modification have to be synchronized simultaneously, has not yet been presented and analysed. This paper closes this gap taking into account that the given and propagated source or target model modifications are in conflict with each other. Our conflict resolution strategy is semi-automatic, where a formal resolution strategy – known from previous work – can be combined with a user-specific strategy. As first result, we show correctness of concurrent model synchronization, that is, each result of our nondeterministic concurrent update leads to a consistent correspondence between source and target models, where consistency is defined by the TGG. As second result, we show compatibility of concurrent with basic model synchronization: concurrent model synchronization can realize both forward and backward propagation. The results are illustrated by a running example on updating organizational models.