Using the Bridge Design Pattern for OSGi Service Update

In the OSGi framework, components cooperate by sharing service objects. The suggested way to replace a service by a newer version consists of updating its containing components which requires a temporary shutdown of the component. Special care must be taken to avoid dangling references to old service instances. As this appears to be an overly expensive strategy, we describe the use of the well-known Bridge design pattern to decouple service replacement from component updates. Instead of registering services only references to instances of automatically generated bridge classes are registered. This solves not only the problem of dangling references but also avoids stopping and starting dependent bundles.