Communication Adapters

Communication adapters are auxillary CANS components, which transmit data physically across the network to connect drivers that span different nodes. To achieve this, these components expose the same DPort interface, appearing to other drivers just as a regular driver. Communication adapters also support two additional kinds of logical connections: (1) between applications and drivers; and (2) between a driver and a service that exports data using an interface other than DPort. To provide the above functionality, adapters establish physical communication links between application wrappers (see below) and execution environments, between two execution environments, and between an execution environment and a service. Multiple logical connections can be multiplexed on this single physical link; the latter can exploit transport mechanisms best matched to the characteristics of the underlying network. Communication adapters can additionally encapsulate behaviors that permit them to adapt to and recover from minor variations in network characteristics. For instance, these adapters can be written to use one of several network alternatives, automatically transitioning between them to improve performance. The continuity semantics upon such reconnection are dictated by the requirements of the data types associated with the adapter's ports.