Today's pervasive computing spaces are developed primarily with proprietary technology and seem to lack a long-term vision of evolution and interoperation. The future pervasive computing environment will comprise a wide variety of devices and services from different manufacturers and developers. We must therefore achieve platform and vendor independence as well as architecture openness before pervasive computing spaces become common places. The Open Services Gateway Initiative attempts to meet these requirements by providing a managed, extensible framework to connect various devices in a local network such as in a home, office, or automobile. By defining a standard execution environment and service interfaces, OSGi promotes the dynamic discovery and collaboration of devices and services from different sources. Moreover, the framework is designed to ensure smooth space evolution over time and to support connectivity to the outside world, allowing remote control, diagnosis, and management. We present the OSGi technology and examine several OSGi development toolkits and products. We also share our experience in using OSGi to build an open, assistive environment that supports independent living for elders.