Capture all changes to an application state as a sequence of events.
We can query an application's state to find out the current state of the world, and this answers many questions. However there are times when we don't just want to see where we are, we also want to know how we got there. ·
Jorge Ressia, Lukas Renggli, Tudor Gîrba, and Oscar Nierstrasz. Proceedings of the 5th Workshop on Models@run.time at the ACM/IEEE 13th International Conference on Model Driven Engineering Languages and Systems MODELS 2010, page 37--48. Oslo, Norway, (October 2010)