he application in the personalization process. In the first scenario, the application assigns all personalization tasks to the PAM-A. This scenario behaves similarly to the PAM-M. When a user submits a query, the application calls the query reformu- lation service before evaluating the enriched query. Another personalization step can be performed after the query evaluation by using the profile-content matching in order to filter the nonrelevant results. Personalization Paradigm in Service Delivery Platforms Contexts Contexts Contexts PAM-A PAM-A PAM-A Profiles Application Profiles Profiles Application Application Content Content Content Figure 10.11 Introducing personalization in applications. In the second scenario, the application aims to have more control on personal- ization. The PAM-A is thus more strongly coupled with the application and services are used during different steps of the query life cycle. For example, the user query can be enriched with profile preferences during the query compilation step and then the query execution can be done using the profile-content matching service. In the last scenario, the application performs all personalization tasks and uses only the PAM-A profile and context management components. For instance, the application may query the PAM-A to get a user profile adapted to a given context. 10.3.3.3 PAM-S: Providing Personalization as an Autonomous Service The PAM-S can be seen as a toolbox of reusable services which can be called by the applications (see Figure 10.12). The PAM-S only receives messages (service invoca- tions), executes the services, and sends the results to the applications. Every applica- tion can call the PAM-S services if messages conform to the meta models. Indeed, the PAMs services can only be applied on profiles, on contexts, and on contents which are instances of the profile or context meta model. Consequently, applica- tions have to be aware of the meta models. In this use case, the PAM-S does not store profile and context instances and is considered 