So the mobile app will have a page where a user enters in about 10 options for criteria. It then must perform some calculations based on a matrix of values and return results. The matrix is controlled by the application owners so the data for the calculations are stored server side. I was looking at using all REST services to access data because it is the most lightweight and seems to work well for mobile (easy to consume). However, this seems to violate the principles of REST. Should I create the server side component as a SOAP service? Or I suppose another option would be to download the matrix to the phone via a REST service, then do all the calculations within the app. This would have the disadvantage of not being quite as easily shared if it needed to be in the future, with say another website.