一. Three main elements in UML
1. basic build block: thing, relationship, diagram
2. rule: name, scope, visibility, integrity, execution
3. common mechanism: specification, adornment, common division, extensiblity mechanism(stereotype, tag value, constraint)
二. Relationship: dependency, association, generalization, realization
三. 9 diagrams: use case, sequence, collaboration, class, object, statechart, activity, component, deployment.
四. Relationship between actor and use case :
1.assocation, demonstration sign: line， actor and use case
2.generalization, demonstration sign: line and clockwise triangle, actor and actor, use case and use case
3.include, demonstration sign: << include>> and broken line, use case and use case
4.extend, demonstration sign: <<extend>> and broken line, use case and use case
五. Relationship between class
1.association,uni-directional association 、bi-directional association、qualified association、reflexive、binary、N-ary, association class, constraint can be on association.
2.aggregation(聚集），demonstration sign: diamond and line, Circle and Style, circle disappears, but style still exists. Has-A
composition（组合）, demonstraion sign: solid diamond and line, Circle and Point, circle disappears, then Point（圆心）也就不存在了。Contains-A
3. generalization,
4. Dependency,
六. StateChart vs. Activity vs. Sequence
StateChart diagram describes the behavior about one object in its life cycle, that is, Object state's Transfer.
Activity diagram describes the control flow from activity to activity, application scenario - multi-thread, analysis of work flow, and concrete algorithm of one operation.
Sequence diagram describes the communication among multi-objects.
七. Component vs. Deployment
They are both diagrams about physical modeling for OO system.
Component diagram can be used for the relationship between original code, execute files.
Deployment diagram is used for understanding distributed system. It's described by Architecuture、Network Engineer, System engineer. Node and Connection are basic concept for deployment diagram. Node comprises processor and device：no computing ability.
Process schedule， preemptive（抢占式）, non-preemptive（非抢占式），cyclic（循环式），executive（算法控制方式）and manual（外部用户控制方式）。