Slide 7 of 31
Notes:
This chart depicts the relationships among four Request for Proposal (RFP) elements—Activity Diagrams, Use Cases, Node Connectivity Diagrams, and Information Exchange Requirements (IERs). Activity Diagrams describe the complete functionality of the system and operators. This scope is reflected by the shaded polygon encompassing the system (cube) and its attendant operators (stick figures inside the polygon). Use cases describe the system behavior or interaction at its boundary with its actors (people or external systems depicted as stick figures) to accomplish a specific function or create a result of value. Therefore, they represent an agreement between the operator community and the developers describing how the system shall function from the user’s perspective and identify the dividing line between activities accomplished by the system and those accomplished by the operators. Node connectivity diagrams identify the primary logical nodes within the system or outside the system where information is produced, consumed, or transported. Lines between nodes indicate logical paths along which information flows. Information exchange requirements identify high level information that flows between nodes and the characteristics of that exchange such as frequency, size, and timeliness.
As indicated in the diagram there are IERs internal to the system that exist ultimately to support a user function, there are IERs that transfer information to or from external systems, and there are IERs that transfer information between the system and its operators. The first two are captured in the IER data base. The last two are explicitly represented by use cases. Because information flows only to support user needs, all three types may be associated with use cases.
