Editing Round-trip engineering (section)

== Overview ==
Round-trip engineering is closely related to traditional [[software engineering]] disciplines: forward engineering (creating software from specifications), [[reverse engineering]] (creating specifications from existing software), and [[Reengineering (software)|reengineering]] (understanding existing software and modifying it). Round-trip engineering is often wrongly defined as simply supporting both forward and reverse engineering. In fact, the key characteristic of round-trip engineering that distinguishes it from forward and reverse engineering is the ability to synchronize ''existing'' artifacts that evolved ''concurrently'' by ''incrementally'' updating each artifact to reflect changes made to the other artifacts. Furthermore, forward engineering can be seen as a special instance of RTE in which only the specification is present and reverse engineering can be seen as a special instance of RTE in which only the software is present. Many reengineering activities can also be understood as RTE when the software is updated to reflect changes made to the previously reverse engineered specification.

=== Types ===
Various books describe two types of RTE:<ref>{{Cite book |last=Sobh |first=Tarek M. |title=Advances in computer and information sciences and engineering |date=2008 |publisher=Springer |others=International Conference on Systems, Computing Sciences and Software Engineering |isbn=978-1-4020-8741-7 |location=New York?}}</ref>{{Rp|page=459}}

* '''partial''' or '''uni-directional''' RTE: changes made to a higher level representation of a code and model are reflected in lower level, but not otherwise; the latter might be allowed, but with limitations that may not affect higher-level abstractions
* '''full''' or '''bi-directional''' RTE: regardless of changes, both higher and lower-level code and model representations are synchronized if any of them altered

=== Auto synchronization ===
Another characteristic of round-trip engineering is ''automatic'' update of the artifacts in response to ''automatically'' detected inconsistencies. In that sense, it is different from forward- and reverse engineering which can be both manual (traditionally) and automatic (via automatic generation or analysis of the artifacts). The automatic update can be either ''instantaneous'' or ''on-demand''. In instantaneous RTE, all related artifacts are immediately updated after each change made to one of them. In on-demand RTE, authors of the artifacts may concurrently update the artifacts (even in a distributed setting) and at some point choose to execute matching to identify inconsistencies and choose to propagate some of them and reconcile potential conflicts.

=== Iterative approach ===
Round trip engineering may involve an iterative development process. After you have synchronized your model with revised code, you are still free to choose the best way to work – make further modifications to the code or make changes to your model. You can synchronize in either direction at any time and you can repeat the cycle as many times as necessary.