Further Reading - Model-Driven and Software Product Line Engineering - page 227

Loughran et al . propose a language - VML , to express how
software components must be composed according to feature
configurations. VML includes constructs that correspond to
possible operations on components such as connect
(component-1, component-2) or disconnect(component-1,
component-2) . VML also supports the specification of
links between features and components, indicating how
the components of the reference architecture model must
be composed according to features selected in feature
configurations. For example, it is possible to specify that the
KeypadReader component must be connected to the common
component LockControlMng using the interface IAccess if
the Keypad feature was selected in a feature configuration.
Listing 8.1 presents the VML specification for this example.

1 Concern LockControl {
2 VariationPoint AuthenticationDevice {

3 Kind: a lternative ;

4 Variant Keypad {

5 SELECT:

6 connect(KeypadReader , LockControlMng)

7 using interface(IAccess );

8 UNSELECT:

9 remove( KeypadReader );

10 }

Listing 8.1. Example of a VML specification

Therefore, VML allows for creating decision models using
its well-structured constructs. Using the VML constructs, it is
possibletorelate(1)asetof effects onthereferencearchitecture
and (2) features in a determinate state (selected/unselected).
For instance, from Listing 8.1, if the Keypad feature is
SELECTED then VML executes commands from lines 6 and 7
elsethe Keypad featureis UNSELECTED andthenVMLexecutes
commands from line 9. Commands from lines 6, 7 and 9 imply
effects onthereferencearchitecture.UsingtheVMLconstructs,
it is not possible, however, to relate (1) a set of effects on the
reference architecture model and (2) a subset of features in