This chapter has shown that transformations can be defined formally using a transformation definition language. To be able to do this, we need to have the metamodels of the source and target languages available.
The transformation definition language, as defined in section 9.2, is not the standard language as it will be defined by the OMG standardization process. At the time of writing, this standardization process is still under way and it seems likely that many different languages will be proposed. It will take some time before this process is finished. The purpose of the transformation definition language in this book is only to explain the formalization of transformation rules.
We have used the transformation definition language to formalize the simple transformations explained in Chapter 2. In the upcoming chapter, the language is used to define some of the example transformations from Chapter 5 and Chapter 6 in a formal manner.