Querying non-conventional data sources is recognized as a major issue in new environments and applications such as those occurring in pervasive computing. A key issue is the ability to query data, streams and services in a declarative way. In this paper, we propose a framework that defines a data-centric view of pervasive environments: the classical notion of database is extended to come up with a broader notion, defined as relational pervasive environment, homogeneously integrating data, streams and active/passive services. It allows declarative definitions of service-oriented continuous queries using a SQL-like language, based on the so-called Serena algebra. We also tackle the design of a Pervasive Environment Management System that handles non-conventional data sources and service-oriented continuous queries.