Operational Nodes of a system, which are where activities are performed, are modeled on an OV-2 diagram. Operational Activities, which are how things are performed, are modeled on OV-5 diagrams. The Activity Based Methodology specifies a step-by-step method on how to build the diagrams and specify the information.
There are two OV-5 diagrams:
▪Node Tree diagram: Build a functional decomposition of Operational Activities and their hierarchy.
▪Activity diagram: Show the flow of information between Operational Activities.
The flow of information between Operational Activities on an OV-5 Activity diagram is accomplished using Input, Control, Output, and Mechanism (ICOM) lines. You specify what Operational Activities are performed on what Operational Nodes using a matrix. (You do not specify this information directly in the Operational Node definition in System Architect; in fact the information isn't even displayed within the Operational Node definition — however it can be displayed on the node symbol. We removed display of it within the Operational Node definition due to performance issues.)
Once that information is specified, you can gain an understanding of the dependencies of Operational Nodes to one another. Remember ICOM arrows are drawn between Activities on an OV-5 diagram, denoting information flow between Activities. When an Activity on a Node (we'll call it the target Node) needs information from another Activity on another Node (we'll call it the source Node) to perform its tasks, then the target Node has an Information Exchange Requirement (IER) that is satisfied by the source Node. In his case a Need line should be modeled between the two Nodes to show that one passes information to the other, or conversely, that the target Node needs the source Node. The name of the ICOM arrow drawn between two Activities is mapped to an IER existing within a Need line drawn between the two corresponding Nodes. A Need line has no name.
Roles that perform the activities
You must also model the organizational chart that specifies line of command and decision making. On the OV-4 Org Chart, you model the hierarchy of Organizational Units and the Roles within them. You then specify the Roles that perform Activities on Nodes in the Operational Activity to Operational Node matrix.
When you have two activities with two or more nodes associated with each activity, then all combinations of Need lines and corresponding IER definitions will be auto-generated between them. However, it is possible that some of the IERs might be invalid for your particular modeling scenario — in that no information is consumed by an activity at a node. By default, all IER’s generated by System Architect are valid. The user can manually specify that the IER is invalid.
Activity Based Methodology (ABM)
The Activity Based Methodology specifies a step-by-step method on how to build the diagrams and specify the information.