The trends of network convergence and mobile accessibility in the Internet are bringing new challenges to the connectivity management of end hosts. Concerning network convergence, the configuration of heterogeneous access networks should be taken into consideration. As for mobile accessibility, seamless handoff between diverse access points is a challenging issue. This article presents the design and implementation of connectivity management middleware (CMM), a channel-based architecture for context-aware connectivity management. This architecture can both provide network awareness to applications and manage network resources in an adaptive fashion. In the case of network awareness, the platform provides interfaces for applications to query network QoS and availability status, as well as subscribe connection events. As for adaptive resource management, channel-based transport services for seamless access switching and disconnection treatment are provided based on a policy mechanism. A prototype is implemented with which experiments were performed in a GPRS-WLAN integrated environment in order to demonstrate the operational correctness of the architecture. Performance metrics are measured and analyzed.