Class diagrams are used to get an idea of how your system should be built. These diagrams will show the interactions of the different aspects of the system, and when making a class diagram, you should start getting an idea of all the data and attributes of each class needed. However, the Sequence diagram should start to give you a clearer picture of the data transfer.

Use Case Diagram We typically will want to start modeling our system with user stories or by developing use cases to be made into a use case diagram. This allows us to figure out all the different types of users that may interact with a system. For example, a e-charting system for a hospital may have adminstrators with special privileges like creating a chart, patients who can access their charts, and people who can make general updates to a chart.

Statechart Diagram State charts are looking at just the system as opposed to the activity diagram that will be explained below. So, typically the beginning state of the system will be waiting for input. We note the data given to the system that cause a transition from one system state to another.

Activity Diagram When creating an activity diagram, we want to consider all the actions that may take place between the start of a process and the end. Actors are not as important in activity diagrams as in other diagrams, the control and focus flows from each action taken to another. The outcomes of actions may split the path taken.

Sequence Diagram Sequence diagrams will show in more depth the data transfer between classes in the context of a single use case. We want to think about classes as being either entity, boundary, or control classes. Entity classes the specific objects and data being transfered around. Boundary classes are interfaces, and only control classes should be "talking" to the boundary class. Control classes are the interactive classes where they act as the inbetween the entity and boundary class; they are more of the "doers".

Communication Diagram Communication diagrams will show more generally the class interactions, but in a communication diagram, you consider actors in the system and their use cases. Also, we want to think about the steps involved in a single use case.

Deployment diagrams are typically created during development. These diagrams show how the software will actually be distributed. It shows the interaction between other systems or peripheral devices; for example, a software system needing to access a printer for some interaction would be shown in a deployment diagram.