Trace

The Trace is an optional part of a Fragment that contains change operations (deltas) that were performed to the Fragment in the past. The usage of the Trace is implementation specific and may be refined in future work. In general, the Trace targets the Model, but could target Instance changes as well. The coarse idea is the following: Each evolution step by the client (e.g. that increments the running version) produces a sequence of Deltas which are added to the Trace. This allows going back in time (reverse operations) and helps to (re-)construct model transformations between different variants and versions. If a new Fragment is created from an existing one, the Trace of the new Fragment is emptied.

Unlike a delta modes (see Ina Schäfer et al.) does a Trace not have the properties of a partially ordered set. A Traces has the properties of a totally ordered set, i.e., a sequence of change operations.