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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.
Next: Support for Legacy Applications
Up: CANS Components
Previous: Services
Weisong Shi
2001-01-08