L5 – Logical States

The L5 Logical States View is a graphical method of describing how a node changes in response to events that affect it.

Concerns Addressed

• Scenario Specification.
• User Requirements Specification.

Background

The L5 View specifies the typical states a node may have and the possible transitions between those states (i.e. changes of state). Triggers for state changes may also be defined. Actions may be associated with a given state or with the transition between states in response to stimuli (e.g. triggers and events).

Usage

• Analysis of business events.
• Behavioural analysis.
• Identification of constraints.

Representation

• Topological (Connected Shapes).
• UML state diagram.

Detailed View Description

The L5 View describes how operational nodes or activities respond to various events by changing state.

Figure 3-346 shows a simple L5 view. The black dot and incoming arrow point to initial states (usually one per diagram), while terminal states are identified by an outgoing arrow pointing to a black dot with a circle around it. States are indicated by rounded corner box icons and labelled by name or number and, optionally, any actions associated with that state. Transitions between states are indicated by one- way arrows labelled with event or action notation, which indicates an event-action pair and shows, when an event occurs, the corresponding action which is executed. This notation indicates the event that causes the transition and the ensuing action (if any) associated with the transition.

Figure 3-346: Example L5 State Transition View

A L5 view represents the sets of events to which the architecture will 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.

Figure 3-357: Example L5 View

States in a L5 view may be nested. This enables quite complex views to be created to represent operational behaviour. L5 states are logical states, specified independently of any given solution. P5, Resource States, provide the solution- specific equivalent to L5, detailing the states that derive from the L5 for a specific Physical Architecture.

Key Elements and Their Relationships

Figure

Meta-Model

The detailed meta-model and element list for L5, Logical States, is at paragraph 4.4.5.