  This paper proposes Commutative Event Sourcing as a simple and reliable
mechanism for model synchronisation, bidirectional model to model
transformations, incremental updates, and collaborative editing. Commutative
Event Sourcing is a restricted form of a Triple Graph Grammar where the rules
or editing commands are either overwriting or commutative. This restriction
gets rid of a lot of Triple Graph Grammar complexity and it becomes possible to
implement model synchronisation manually. Thus, you are not restricted to Java
as your programming language and you do not need to use a proprietary library,
framework, or tool. You do not even have to dig into graph grammar theory.
