Edapt provides an extensible framework for reducing the migration effort that results from the evolution of Ecore models. Since the number of existing instances of a successful modeling language typically outnumbers the number of editors, interpreters and transformations, instance migration effort dwarfs tool reconciliation effort. Consequently, Edapt clearly focuses on the migration of instances in the first step. However, we plan to make it extensible with respect to the migration of other artifacts like editors, interpreters and transformations. The basic idea behind Edapt is to obtain the changes between two versions of an Ecore model, and to enrich them with information about how to automatically migrate existing instances. Edapt will support a pluggable mechanism to obtain the changes between two Ecore model versions along with two examples: the operation-based and the difference-based approach.
The operation-based approach is similar to code refactoring. The developer modifies the Ecore model using predefined operations which encapsulate the adaptation of the Ecore model as well as the migration of the instances. The execution of these operations is recorded in a history which can then be used to migrate existing instances. Being fully automated, these operations thus significantly reduce the effort associated with migration. Moreover, they provide a more systematic way to adapt Ecore models, e.g. they allow the developer to better assess the impact on instances. However, not all changes can be covered by existing operations. Therefore, Edapt provides a way to manually change the Ecore model and attach information on how to migrate instances.
The difference-based approach compares two versions of an Ecore model, and evaluates the differences using EMF Compare. As opposed to the operation-based approach, this neither requires the developer to modify the Ecore model in pre-planed steps nor editor integration. Furthermore, it makes the difference based approach easily applicable to Ecore models which are not the primary artifact of modification, but are derived from other artifacts.
Both approaches complement each other: The operation-based approach allows the developer to capture the migration of instances while adapting the EMF model. While this can be more systematic, it also causes some overhead. In contrast, the difference-based approach allows the developer to enrich the changes later on with instructions on how to migrate existing. While we will provide these two approaches as examples, Edapt will be extensible with respect to other mechanisms to obtain the changes.