Extending SysML with AADL Concepts for Comprehensive System Architecture Modeling

Subcomponents and interactions. Subcomponents in a component implementation can be other component types or component implementations.
Connections and call sequences are used to describe the interactions among
subcomponents. In Figure 3, subcomponents of the component implementation
redundant pattern.primary backup are listed in lines 13-15. Connections
among these subcomponents are declared in lines 17-22.

Flow path implementations. A flow path implementation describes a sequence
of paths through and connections among subcomponents within a
component implementation. This path is a realization of the corresponding
flow path declared in the component type declaration [14]. In Figure 3, the
flow path implementation declared in line 24 refines the flow path specification
declared in line 7.

Modes. An AADL component implementation declaration may contain the
declaration of modes and mode transitions. Modes represent alternative operational states of a system or component [14]. Transition from one mode to
another is triggered by events. In Figure 3, lines 26-28 declare three modes
of redundant pattern.primary backup. In addition, lines 29-31 show the
mode transitions among these three modes.

In AADL, a mode is an explicit configuration of its contained elements, e.g.,
subcomponents and connections. The in modes clause in the declaration of
a component implementation is used to specify the active elements in each
mode. The declarations of the connections in lines 17-20, in Figure 3, also
contain the specification of the modes these connections are active in.