In this work, we study the energy management system (EMS) in the customer domain of the Smart Grid. We discuss the desired features and design issues, highlight the characteristics and identify the challenges. To address the challenges, we propose the innovative framework of Pervasive Service-Oriented Networks (PERSON). The core idea is to utilize a heterogeneous network as the information infrastructure, abstract the functionalities into services, and deploy context- aware intelligence to address the system dynamics. Furthermore, based on the framework of PERSON, we implement a powerful yet cost-effective EMS. The effectiveness of the EMS is demonstrated by a demand response application.