ances. The relation- ships between GPM and CPM (respectively GCM and CCM) represent customiza- tion relationship; the version number discriminates between different customized models. Profiles and contexts are key elements of any personalization and/or contextu- alization application. Therefore, these concepts constitute a basis of our PAM for SDPs that provides a set of personalization services using them. In the next section, we introduce the PAM, present the services it provides, and discuss the different deployment architectures it supports. 10.3 A PAM for SDPs Our definition of a PAM aims to provide a generic set of concepts and techniques that should be deployed over a given system architecture to make the target applica- tions adaptable to users' profiles and contexts. Figure 10.5 gives an overview of the main components of a PAM. The PAM is composed of three layers: (1) a persistency layer, (2) a functional layer, and (3) a communication layer. Service Delivery Platforms Services access API Context Update of Instantiation Profile profiles and of profiles contextualization discovery contexts and contexts Profile and context Query Profile-context matching reformulation binding Profile and context access API Profile catalog Context catalog Figure 10.5 Personalized access model architecture. The persistency layer deals with the storage and the access to the profiles and contexts. It includes the profile and the context catalogs. The functional layer is composed of the profile management services, context management services, and personalized access services. Among these services, we distinguish offline services and online services. The former set is used at the design time of a personalized application, while the latter is used at the execution time. A more detailed description of the services offered by the platform follows. Finally, the communication layer provides a communication interface between the PAM and users or applications. The role of this layer is, on one hand, to give access to the profiles and 