UML PROFILE FOR SAVECCM - Research

SaveCCM
Quality attributes
In addition to ports, the interface of an element may contain quality attributes
each associated with a value and possibly a confidence measure. These attributes
hold the information about the (worst case) execution time, reliability estimates,
safety models etc. The quality attributes are used for analysis, model extraction
and for synthesis. A list of quality attributes is included in the definition of
components.
5.3.1 Components
Components are the main architectural element in SaveCCM, it is the basic unit
of encapsulated behaviour. The functionality of a component is usually
implemented by a single entry function in C, but it is also possible to have more
complex components that consist of a number of possibly communicating tasks.
Component is defined by an entry function, associated ports and optional quality
attributes. The only allowed dependencies between components are the ones
explicitly captured through component ports.
Each port providing data that is used as a parameter of the entry function is
marked as a bind port.
Execution model
On a high level, a component is either waiting to be activated (triggered) or is
executing. Initially, component is inactive. When all trigger input ports are
activated, component has been triggered and it changes its state from inactive to
executing state. The first phase of execution is read phase – the current value at
each input data port is stored internally to ensure consistent computation. Then
component performs its computations based on this inputs and possibly an
internal state. After a computation (execute) phase is finished (the function has
been computed, or in case of a complex component – when all tasks have
finished), starts the write phase where the output is written to the output data
ports. Finally, the component activates the outgoing trigger ports and returns to
idle state by resetting input trigger ports.
This execution model, with "read – execute – write" semantics ensures that
when a component is activated (triggered), the execution is independent of any
concurrent activities.
Component realization
Each component can have any number of models associated to it. A model is
an element which implements component’s behaviour. It presents an instance of a
component. A model can be an external file, or embedded as text within the
element.
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