The design of data-centric pervasive applications in dynamic environments is raising more and more interests in many application domains. To design pervasive applications, we take advantage of recent advances in database management systems dealing with streams and services: new systems exist that simplify pervasive application deployment. We believe that the field is now mature and that conceptual data models like Entity-Relationship models could be revisited at the light of the pervasive application requirements. In this paper, we propose to extend an Entity-Relationship model to a new conceptual model, the so-called XD-ER equipped with some key notions: dynamic datasource types to model both streams and services and dynamic relationship types to link dynamic datasource types to classical entity types. Based on the SoCQ data model, we point out how to transform a conceptual XD-ER schema into XD-Relations straightly implementable in the SoCQ engine. The use of our model is shown through a running example.