1. A method executed by a central processing unit (CPU) for extracting a platform independent model (PIM) from a composite application, the method comprising: identifying existing implementation artifacts of the composite application, wherein the implementation artifacts comprise platform specific legacy code and artifacts; transforming the identified implementation artifacts for generating a platform specific model (PSM), wherein generating a PSM includes one or more transformations between the implementation artifacts and one or more meta-models of the PSM; and transforming the PSM for generating a PIM, wherein generating a PIM includes one or more transformations between the one or more meta-models of the PSM and one or more meta-models of the PIM; wherein one or more transformations between elements of the one or more meta-models of the PSM and elements of the one or more meta-models of the PIM include one or more mappings that define rules for mapping between the elements of the one or more meta-models of the PSM and the elements of the one or more meta-models of the PIM.