UML Basics
Types of UML Diagrams:
- Use Case:
A use case diagram is a simple diagram that shows who is using your system and what processes they will perform in the system.
Best use: The use case diagram is an extremely important diagram for the Requirements Gathering and Analysis workflows. Throughout the entire development, all work should be traceable back to the Use Case diagram. - Class:
A Class diagram show a set of classes in the system and the associations and inheritance relationships between the classes. Class nodes might also contain a listing of attributes and operations.
Best Use: The Class Diagram is essential for showing the structure of the system and what needs to be programmed. Most UML case tools can generate code based on the class diagram. - Object:
An Object diagram shows specific object instances and the links between them. An Object diagram represents a snapshot of the system objects at a specific point in time.
Best Use: The Object diagram can be used to clarify or validate the class diagram. - Activity:
An Activity diagram is essentially a flow chart with new symbols. This diagram represents the flow of activities in a process or alogrithm.
Best Use: Even in an OO system, it can sometimes be useful to consider processes without thinking in terms of objects. Activity diagrams are especially useful for modeling real world business systems during the Requirements Gathering workflow. - Collaboration:
The Sequence diagram and the Collaboration diagram both show processes from an object oriented perspective. The main difference is that the layout of the Collaboration diagram puts more focus on the objects rather than the sequence.
Best Use: Sequence diagrams are typically easier to read than Collaboration diagrams. Many people prefer to only use Sequence diagrams. A Collaboration diagram might be preferable if you want more focus on the objects than the sequence. - Sequence:
Sequence diagrams show a process from an object oriented perspective by showing how a process is executed by a set of objects or actors.
Best Use: The Sequence diagram is essential for assigning responsibilities to classes by considering how they can work together to implement the processes in the system. - Statechart:
A statechart diagrams shows how a particular object changes behavioral state as various events happen to it. Best Use: The Statechart diagram is very useful in understanding objects that change behavioral states in significant ways.
- Deployment:
A Deployment diagram show the hardware nodes in the system. The Deployment diagram is useful for seeing how a distributed system will be configured. Software components might be displayed inside the hardware nodes to show how they will be deployed.
find actors(depend on system boundary):
Use case diagrams and use case relationships are secondary in use case work. Use cases are text documents. Doing use case work means to write text.
activity diagram with partitions:
