Transformations Have to be Developed ReST Assured

Model transformations do not simply appear. They have to be not-so-simply developed. In early phases of development, there may exist only an intuition or an educated guess on some of the characteristics of the transformation. Instead of assuming a pre-existing complete transformation specification, we embrace change and develop transformations incrementally, gradually refining them into more complete ones as the body of knowledge of the domain grows. We present an iterative process encompassing requirements capture, design and implementation of model transformations. We describe partial transformations as so called transformational patterns and iteratively refine them. We apply the approach to developing a transformation that is used in building APIs that comply with the ReST architectural style.