The proliferation of radio frequency identification systems in application domains such as supply chain management requires an IT infrastructure that provides RFID device and data management and supports application development. In this paper, we discuss these application requirements in detail. We also contend that the characteristics of passive RFID technology introduce constraints that are unique to the development of middleware for the RFID domain. These constraints include the occurrence of false negative reads, tag memory variations, the heterogeneous reader landscape, and the limited communication bandwidth available to RFID readers. To address these constraints and the application requirements for filtered and aggregated RFID data, we developed Accada, an open source RFID platform. The paper shows that the Accada implementation, which is based on a set of specifications developed by the EPCglobal community and a number of extensions, such as the surrogate concept and the virtual tag memory service, addresses the majority of the application requirements and limitations of passive RFID technology.