Aspect-Oriented Formal Specification for Real-Time Systems - Advances in Computational Science and Engineering - page 26

Collaboration Diagram
Collaboration diagram emphasizes on the structural organization of objects that send
and receive messages. A collaboration diagram shows a set of objects, links among
those objects, and messages sent and received by those objects. It shows classifier
roles and the association roles. A classifier role is a set of features required by the
collaboration. Classifier roles for core classes implement the core features required by
the system. Classifier roles for aspects are services required by the core classes which
are otherwise tangled with the roles of the core functional features[33]. The time
aspect is time service required by the core classes in real-time systems.
The elevator control system expresses the time features as an object of
TimeAspect. The behavior of the time object interacting on other objects of the sys-
tem is shown in Fig. 5.
Fig. 5. Collaboration Diagram of The Elevator Control System
Statecharts
Statecharts can model the intra-object aspectual behaviors well in the object-oriented
programming paradigm. However, current specification of statecharts doesn't support
aspect-oriented modeling. To support aspect-orientation within the context of state-
charts, we need to provide a mechanism by which the modeler can express these as-
pects. Statecharts modeling aspects should consider the association between aspects
and transitions instead of states. Orthogonal regions, which are shown as dashed lines
in statecharts, combine multiple simultaneous descriptions of the same object. The
aspects can be expressed as objects, which have their own sub-states. Interactions
between regions occur typically through shared variables, awareness of state changes
in other regions and message passing mechanisms such as broadcasting, and propa-
gating events [34]. The statecharts of the elevator control system is shown in Fig.6.
Timing behaviors are described by the advanced features of statecharts, and the time
concern is achieved implicit weaving with the core functionality of the system. State-
charts refine the model and aspects codes can be generated automatically by existing
CASE tools.