System Views (SV) [Physical, Specification or Solution Views]
SV-10c Resource Event-Trace Description v1.2
The Resource Event-Trace Description provides a time-ordered examination of the interactions between resources. Each event-trace diagram will have an accompanying description that defines the particular scenario or situation.
Background:
SV-10c Products are valuable for moving to the next level of detail from the initial solution design, to help define a sequence of functions and system data interfaces, and to ensure that each participating Resource or System Port role has the necessary information it needs, at the right time, in order to perform its assigned functionality.
Usage:
- Analysis of resource events impacting operation
- Behavioural analysis
- Identification of non-functional system requirements (input to SRD)
Data objects:
The data in an SV-10c can include:
- Lifelines (each associated with a Functional Resource or a System Port)
Representation:
- Topological (Connected Shapes)
- UML Sequence Diagram (Preferred)
Detailed Product Description:
The Resource Event/Trace Description specifies the sequence in which data elements are exchanged in context of a Resource or System Port.
The SV-10c is typically used in conjunction with the Resource State Transition Description (SV-10b) to describe the dynamic behaviour of resources.
Resource Event/Trace Descriptions are sometimes called sequence diagrams, event scenarios or timing diagrams. The diagram below shows the components of an SV-10c. The items across the top of the diagram are functional resources or system ports. The MODAF Meta-Model is an extension of the UML 2.1 Meta-Model which specifies that the lifelines show in a sequence diagram must be connectable elements – i.e. properties or ports. In practical terms, this means that the subject of each lifeline must be either a part (i.e. a subsystem, role, etc. which is part of another resource) or a System Port. For this reason, any MODAF SV-10c should, if possible, show the owning resource as well as the resource / port which is the subject for the lifeline.
Systems Event-Trace Description (SV-10c)
Specific points in time can be labelled running down the left-hand side of the diagram. Arrows between the lifelines represent events, positioned along the vertical access to show the time of the events. The direction of the event lines represents the flow of information from one resource / port to another. The Resource Event-Trace Description provides a time-ordered examination of the data elements exchanged between participating resources(external and internal) or system ports. Each event-trace diagram will have an accompanying description that defines the particular scenario or situation.
The data content of ‘messages’ that connect life-lines in an SV-10c View Product may be related, in modelling terms, with resource interactions (SV-1, 3), data flows (SV-4, 6) and data schema entities (SV-11) modelled in other views.
Page version 1.2, dated 1st July 2008