I wanted to put this together as an easy guide for students for the diagrams required for MSC 525.

Purpose: To identify the entities within the system scope.

• Entities are really entities. Make sure none of the entities on your diagram are processes. The entity names should be nouns. They are "people, places or things about which we wish to collect information."
• The relationships between the entities are labeled. The labels show the relationship between the entities, not data flow.
• Cardinality is correctly diagrammed on the relationship lines.
• Primary and foreign keys are correctly identified.
• In a fully-attributed ERD, all attributed are identified.
• In a fully normalized ERD, the entities are in 3^rd normal form.

Purpose: To identify the major processes (functions) in the system and break them down (decompose them) all the way down to the "event" level. The FDD is a hierarchical chart that shows (in rectangular boxes) the System as a whole is the highest level, the next level identifies highest level processes, the next level identifies the next highest level processes and so forth.

Checklist:

• Does the very top box represent my entire system?
• Does each level of the hierarchy provide an additional level of detail?

Purpose: To show the detail of the system at the event level.

The system diagram is the compilation of all the events in the FDD and their inputs, outputs, and inter-relation.

• Are all the processes in the system within the scope of the system being designed?
• Are all data stores entities (things about which we wish to collect information?
• Do all processes have at least one input and at least one output?
• Do the lines going between the items (processes, actors, data stores, external entities, etc) identify the inputs and outputs of processes?

Purpose: To identify the scope of the system. In other words, to identify the "Context" of the system to be designed.

The Context Diagram should include a process box (rounded rectangle), normally roughly in the center of the page. The inputs and outputs of the system would normally be external entities (not entities within the system being designed). Think of the Context Diagram this way: What are the inputs and outputs to my system. The lines on the diagram represent what those inputs and outputs are.

• Is there only one process, which identifies the system being designed?
• Are all other items (entities, data stores, etc) not going to be a part of the system? The external agents could be external data stores, entities, or processes, but none should be within the boundary of the system as you define it.
• Do all the lines on the diagram identify inputs and outputs to the system as a whole (the process box roughly in the center of the diagram)?

Notice that the system itself is fully contained in "Member Services System."