Modeling

After the process of gathering information about how a organization work and identify what the user need, modeling comes as a following. With the method of modeling, it is capable of abstracting a complex problem into small ones, which is easier for analysts to find solutions and solve them one by one, helping analysts concentrate on specific domain. Most importantly, it helps analysts get a clear understanding of a system, allowing them to communicate with customers more easily.

The UML provides several different kinds of diagrams aiming to view system requirement in different ways, which help analysts focus on specific information in different levels. First of all, the process of events collection is essential, which identify all the operations in or out of a company. It forms foundation for drawing UML diagrams. With the completion of events documentation, domain model class diagram follows, identifying the "things" in an organization based on the documentation of events. Class diagram plays a potential important role in drawing the sequence diagram and state machine diagram, as both of them required to access the data and methods that classes possess, while activity diagram is fully dependent on use case diagram only.

In terms of level of views, use case is the highest. It is easy to understand for customers, a good way to communicate and clarify the understanding of system requirement. Following this level of view, activity diagram details the flows of activities. But it only mention what kinds of work will be done and how they interact with each other. Therefore, a more low level of view, sequence diagram, details what information and what actions will be passed between system and user. It has relationships with both activity diagram and state machine diagram, which is fully dependent on domain model class diagram, while activity diagram is dependent on use case. Another view is state machine. It shows in detail how the actions flow and changes states of objects. The most difference with activity diagram and sequence diagram is that it can show how the objects' state change.