The SvcV-10b “Services State Transition Description” is a graphical method of describing a resource (or function) response to various events by changing its state. The diagram basically represents the sets of events to which the resources in the Activities respond (by taking an action to move to a new state) as a function of its current state. Each transition specifies an event and an action. [1]

DoDAF Architecture Framework Version 2.02 – Page 193

The explicit time sequencing of service functions in response to external and internal events is not fully expressed in SvcV-4 Services Functionality Description. SvcV-10b can be used to describe the explicit sequencing of the service functions. Alternatively, SvcV-10b can be used to reflect explicit sequencing of the actions internal to a single service function, or the sequencing of service functions with respect to a specific resource. [1]

The intended usage of the SvcV-10b includes: [1]

  • Definition of states, events, and state transitions (behavioral modeling)
  • Identification of constraints

The SvcV-10b relates events to resource states and describes the transition from one state to another.

The SvcV-10b is based on the state chart diagram. A state machine is defined as “a specification that describes all possible behaviors of some dynamic view element. Behavior is viewed as a traversal of a graph of specific states interconnected by one or more joined transition arcs that are triggered by the dispatching of series of event instances. During this traversal, the state machine executes a series of actions associated with various elements of the state machine.” State chart diagrams can be unambiguously converted to structured textual rules that specify timing aspects of events and the responses to these events, with no loss of meaning. However, the graphical form of the state diagrams can often allow quick analysis of the completeness of the rule set, and detection of dead ends or missing conditions. These errors, if not detected early during the solution analysis phase, can often lead to serious behavioral errors in fielded capabilities and to expensive correction efforts. [1]

The SvcV-10b models state transitions from a resource perspective, with a focus on how the resource responds to stimuli (e.g., triggers and events). As in the OV-6b “Operational State Transition Description”, these responses may differ depending upon the rule set or conditions that apply, as well as the resource’s state at the time the stimuli is received. A change of state is called a transition. Each transition specifies the response based on a specific event and the current state. Actions may be associated with a given state or with the transition between states. A state and its associated actions specify the response of a resource or service function, to events. When an event occurs, the next state may vary depending on the current state (and its associated action), the event, and the rule set or guard conditions. [1]

The SvcV-10b can be used to describe the detailed sequencing of service functions described in SvcV-4 “Services Functionality Description”. However, the relationship between the actions included in SvcV-10b and the functions in SvcV-4 depends on the purposes of the Architectural Description and the level of abstraction used in the models. The explicit sequencing of functions in response to external and internal events is not fully expressed in SvcV-4 Services Functionality Description. SvcV-10b can be used to reflect explicit sequencing of the functions, the sequencing of actions internal to a single function, or the sequencing of functions with respect to a specific resource. [1]

States in a SvcV-10b model may be nested. This enables quite complex models to be created to represent Services behavior. Depending upon the architecture project’s needs, the SvcV-10b may be used separately or in conjunction with the SvcV-10c “Services Event-Trace Description”. [1]

AcqTips:  

  • The DoDAF descriptions in this website are very generic and are mostly taken from the DoDAF Architecture Framework website. Make sure you visit the actual website for the most update information and a more thorough explanation of each viewpoint.
  • DoDAF Version 1.0, although outdated, has some good examples on how to construct AV’s, OV’s, and SV’s.

AcqLinks and References:

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