In order to support multimedia applications in mobile environments. it will be necessary for applications to be aware of the underlying,network conditions and also to be able to adapt their behaviour and that of the underlying platform. This paper focuses on the role of middleware in supporting such adaptation. In particular, Ive investigate the role of open implementation and reflection in the design of middleware platforms such as CORBA. The paper initially extends CORBA with the concept of explicit binding, where path of communication between objects is represented as first class objects. We then introduce the concept of open bindings which support inspection and adaptation of the path of communications. An implementation of open bindings is described, based on the Ensemble protocol suite from Cornell University.