Operational Views (OV) [Logical Views]

OV-6c Operational Event-Trace Description v1.2

The Operational Event-Trace Description provides a time-ordered examination of the information exchanges between participating Operational Nodes as a result of a particular scenario. Each event-trace diagram will have an accompanying description that defines the particular scenario or situation.

Background:

Operational Event/Trace Descriptions, sometimes called sequence diagrams, event scenarios, or timing diagrams, allow the tracing of actions in a scenario or critical sequence of events. The OV-6c can be used by itself or in conjunction with an Operational State Transition Description (OV-6b) to describe the dynamic behaviour of processes. The diagram below shows the components of an OV-6c. The items across the top of the diagram are operational nodes, usually roles or organisations, which must take action based on certain types of events.

Each operational node has a vertical timeline associated with it. Specific points in time can be labelled running down the left-hand side of the diagram. Directed lines between the node time lines represent events, and the points at which they intersect the timelines represent the times at which the nodes become aware of the events. The direction of the event lines represents the flow of control from one node to another based on the event.

Usage:

Data objects:

The data in an OV-6c can include:

Representation:

Detailed Product Description:

OV-6c is valuable for moving to the next level of detail from the initial operational concepts. An OV-6c Product helps define Node interactions and operational threads.

The OV-6c View can also help ensure that each participating Operational Node has the necessary information it needs at the right time in order to perform its assigned Operational Activity.

OV-6c allows the tracing of actions in a scenario or critical sequence of events. OV-6c can be used by itself or in conjunction with OV-6b to describe the dynamic behaviour of business processes or a mission/operational thread. An operational thread is defined as a set of operational activities, with sequence and timing attributes of the activities, and includes the information needed to accomplish the activities. A particular operational thread may be used to depict a military capability. In this manner, a capability is defined in terms of the attributes required to accomplish a given mission objective by modelling the set of activities and their attributes. The sequence of activities forms the basis for defining and understanding the many factors that impact on the overall military capability.

The following figure provides a schematic.


OV-6c Schematic

The Framework does not endorse a specific event-trace modelling methodology, however, UML sequence diagrams seem the most appropriate for this purpose. If UML is not used, an OV-6c Product may be developed using any modelling notation that supports the layout of timing and sequence of activities along with the information exchanges that occur between Operational Nodes for a given scenario. Different scenarios will be depicted by separate diagrams.


OV-6c Example (Source: DCSA)

The Figure below shows an example OV-6c Product using a UML Sequence Diagram. The items across the top of the diagram are Operational Nodes, usually organisations, organisations types, or human roles, which take action based on certain types of events. Each Operational Node has a lifeline associated with it that runs vertically. Specific points in time can be labelled on the lifelines, running down the left-hand side of the diagram. One-way arrows between the Node lifelines represent events, and the points at which they intersect the lifelines represent the times at which the Nodes become aware of the events. Events represent information passed from one lifeline to another and actions associated with the event. Labels indicating timing constraints or providing descriptions can be shown in the margin or near the event arrow that they label. The direction of the events represents the flow of control from one Node to another.


OV-6c Example

The information content of ‘messages’ that connect life-lines in an oV-6c View Product may be related, in modelling terms, with the information flows (OV-3, OV-5) and information entities (OV-7) modelled in other views.

Service-Oriented Architectures

If the architect is developing a Service-Oriented Architecture (SOA), an OV-6c product may be used to show the sequence of interactions required to support operational activities. An SOA OV-5 product shows which services support which operational activities, however it may be useful to show how those services are required to interact in order to support operations. An SOA OV-6c shows lifelines for services, and the sequence of interactions between those services:


OV-6c Services Example

Page version 1.2, dated 20th June 2008

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