Composition Viewpoint

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Viewpoint

SAS_QP_COMP

SAS_QP_COMP : Composition Viewpoint
Purpose The Composition viewpoint describes the way the architecture subject is recursively structured into constituent parts (packages and classes in the object-oriented viewpoint) and establishes the roles of those parts.
Concerns allocation of functionality and responsibilities the major constituents of the architecture subject mechanisms for extension and reuse
Model Kind The UML class diagram shown in Figure SAS-COMP (static view) depicts core classes comprising QP Framework and their relation to classes in the QP Application shown at the bottom of Figure SAS-COMP. Remarks Because the class diagram in Figure SAS-COMP is drawn in a traditional way (with base classes on top and derived classes below), the layering in this class diagram is reversed compared to the package diagram in Figure SAS-CTXT. Figure SAS-COMP: Core classes in QP Framework and their relation to QP Application.

Views

The following traceable architectural views explain the main QP Framework sub-packages and classes, their responsibilities, and relationships:

SAS_QP_COMP_SLR

SAS_QP_COMP_SLR : QP Framework Sub-layers
Description The QP Framework internally is further decomposed into the following sub-layers: SAS-COMP [10] QEP Event Processor layer is a sub-package of QP Framework, which implements Events and State Machines. Note QEP Event Processor is intentionally separated out to allow QP Applications to directly use just the passive state machines (without Active Objects). QP Applications that use just the QEP Event Processor can still benefit from the QM modeling tool↑, which can generate code that requires only passive state machines. SAS-COMP [20] QF Active Object Framework layer is a sub-package of QP Framework, which implements Active Objects and Time Events.
Backward Traceability SRS_QP_NF_03: QP Framework shall be modular. SRS_QP_NF_04: QP Framework shall be layered.
Forward Traceability

SAS_QP_COMP_CLS

SAS_QP_COMP_CLS : QP Framework Classes
Description SAS-COMP [11] The QEvt class represents events in QP Framework. It can be instantiated directly (concrete class), in which case it represents events without parameters. QP Applications can also inherit and extend QEvt to add custom event parameters. Examples of events with parameters are provided as QP Application classes EventA and EventB (SAS-COMP [01]). SAS-COMP [12] The QAsm class is the abstract base class (ABC) for all state machines in QP Framework. The QAsm class specifies the abstract state machine interface. SAS-COMP [13] The abstract QHsm class derived from QAsm implements the state machine interface init() and dispatch() according to the State Machine Implementation Strategy optimized for manual coding. QHsm provides support for hierarchical nesting of states, entry/exit actions, initial transitions, and transitions to history in any composite state. This class is designed for ease of manual coding, but it is also supported by the QM modeling and code-generation tool↑. SAS-COMP [14] The abstract QMsm class derived from QAsm implements the state machine interface init() and dispatch() according to the State Machine Implementation Strategy optimized for automatic code generation. QMsm provides support for all hierarchical state machine features listed in SRS_QP_SM_20 and sub-requirements plus submachines and submachine states. This class is designed for automatic code generation, and requires the QM modeling and code-generation tool↑. SAS-COMP [23] The abstract QActive class is a base class for derivation of concrete Active Objects in the QP Application. QActive encapsulates the unique priority, event-queue, execution context, and state machine for the Active Object. QActive inherits QAsm, which means that an Active Object in QP can be treated as a state machine with the standard interface. QActive implements this interface by delegating to the QHsm state machine implementation. SAS-COMP [24] The abstract QMActive class derives from QActive base class, so it inherits all its properties. The only difference is that, QMActive implements the state machine interface by delegating to the QMsm state machine implementation. SAS-COMP [21] The QTimeEvt class derived from QEvt represents Time Events in QP (sometimes called timers). QTimeEvt can be instantiated directly (concrete class). Upon instantiation QTimeEvt gets associated with a given event signal, clock tick rate, and Active Object instance (owner). A QTimeEvt can be then armed to time out only once (one-shot) or periodically. Several QTimeEvt can time out simultaneously in parallel.
Backward Traceability SRS_QP_EVT_00: QP Framework shall provide Event abstraction to QP Application SRS_QP_SM_00: QP Framework shall provide support for hierarchical state machines both for Active Objects and for passive event-driven objects in the Application SRS_QP_AO_00: QP Framework shall provide the Active Object abstraction to QP Application SRS_QP_TM_00: QP Framework shall support Time Events.
Forward Traceability SDS_QP_QEvt: QEvt event class. QEvt: Event class QEvt::sig: Signal of the event (see Event Signal) QEvt::evtTag_: Event "tag" containing pool-ID (indicating which event pool it came from) plus event marker SDS_QP_QAsm: QAsm Abstract state machine class. SDS_QP_QHsm: QHsm State machine class. SDS_QP_QMsm: QMsm State machine class. SDS_QP_QActive: QActive Abstract Active Object class. SDS_QP_QMctive: QMctive Abstract Active Object class. SDS_QP_QTimeEvt: QTimeEvt time event class.

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