ystems CS control (CSCFs, MGCF, (HSS, PCRF, layer MRF, etc.) Circuit-switching network CS transport IP-Connectivity Access Network (NGN, Transport layer NGMN) Figure 3.5 WIMS 2.0 SDP deployment. Service Delivery Platforms platform, IMS Exposure Layer, and User Profile) and also the existing ones (IMS Enablers and Core IMS). For instance, a case for the latter would be the "access control entity" in the WIMS 2.0 reference model; here it is mapped onto a general gateway for securing the access of third parties to the service delivery domain, that is, the integrator toward third parties of the SDP of the layered architecture. As for WIMS 2.0 specific entities, the IMS Exposure Layer is located at the Service Exposure Layer of the layered architecture, while the rest of WIMS 2.0 functional entities are considered service-platform and thus, they are represented in the Service Application Layer. That would be the case for the IMS Thin Client, containing service logic for providing end-user application online representations of an IMS phone; the functional entities of WIMS 2.0 related with content and media delivery or generation are gathered under a service platform called UGC 2.0 at the Service Application Layer, except for the database containing the user IDs and preferences, which is stored together with other user data at the User Profile direc- tory (a common enabler) at the Service Enabling Layer; and finally, the IMS 2.0 PSE platform is regarded as a container for end-user applications, in fact, the Portable Service Elements. 3.3 SDP in the Cloud One of the most important transitions from the Grid Infrastructure to the cloud infrastructure has been the change of the W3C Web Services (WS-*) for the REST {REST} way in designing services. This makes a small philosophical change from the plain SOA to a ROA (Resource Oriented Architecture) where the different ser- vices emerge as a set of Resources to be reused and composed by the different players; usually as a mash-up of resources. This approach has been proven qui