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An AADL instance model represents an instantiated system. Such an instance model may
represent a fully instantiated system, i.e., a system that has been described in AADL down to
the level of individual threads and individual execution platform elements, or it may represent an
instantiation of a partially specified system, i.e., a system that has been described in AADL with
some of the subcomponents or implementations of subcomponents not yet specified.
In a fully specified instance model, the leaf components of the component instance hierarchy are
thread, device, processor, bus, and memory component instances. The leaf component
instances have their features instantiated as FeatureInstances. Port groups are recursively
instantiated into their contained features. Semantic port connections are represented in the
instance model as PortConnectionInstances between the port instances of these leaf component
instances.
In a partially specified instance model, the component instance hierarchy is expanded as much
as possible, i.e., down to subcomponents with a component type as classifier and either no
component implementation or a component implementation with no subcomponents or
subcomponents without classifiers. The leaf component instances have their features
instantiated. PortConnectionInstances are created between the port instances of these leaf
component instances. These port connection instances do not represent semantic connections
as defined in the standard as they do not connect threads, processors, and devices. However,
they permit partially specified instance models to be processed as low fidelity models of a
system.
Flow specifications are represented in an instance model through FlowSpecInstances and
EndToEndFlowInstances. Both are contained in component instances. An
EndToEndFlowInstance consists of a sequence of references to FlowSpecInstances of the leaf
component instances involved in the flow and PortConnectionInstances that represent the flow
between these leaf components. |
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