Rookie practical UML - activity diagram

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Activity diagrams

Activity diagrams （activity diagram） It clarifies the workflow of business use case implementation . Business workflow describes what a business must do to provide the value it needs to the business actor it serves , Business use cases consist of a series of activities , Together they generate some artifacts for the business protagonists . A workflow usually consists of a basic workflow and one or more alternative workflows . The structure of the workflow is illustrated by an activity diagram .

purpose

The activity chart is UML Another common tool for modeling the dynamic behavior of a system , It describes the sequence of activities , Show the control process from one activity to another , Activity diagram is essentially a flow chart , Activity diagrams focus on the flow of control from one activity to another , It's an internal process driven process .

Activity diagram components

1、 Activity state diagram （activity）： Used to express the non atomic operation in the state machine

2、 Action state （actions）： It refers to the uninterrupted action of atoms , And after the completion of this action by completing the transition to another state

3、 Action state constraint （action constraints）： Used to constrain the action state , There are pre conditions and post conditions

4、 Action flow （control flow）： The transition between actions , Use a straight line with an arrow to show , The direction of the arrow points in the direction of turning

5、 The starting point ： Start node of the activity , Solid black dots

6、 End ： It means the end of the whole activity , Circle with black dot inside

7、 object ： A rectangular box

8、 Object flow ： Is the dependency between the action state or activity state and the object , Indicates that the action uses the object or the effect of the action on the object . An object can have multiple actions .

9、 Branching and merging ： Use a diamond to show , It has a transformation （ The arrow points out to the branch symbol ）, One or more departures from the switch （ The arrow points out from the branch symbol ）. Each departure transition will have a monitoring condition , Used to indicate what conditions are met when the transformation

10、 Diverge and merge ： Fork is used to say that the action flow is divided into two or more branches running concurrently , The join is used to synchronize these concurrent branches , In order to accomplish a thing together , Objects may have two or more concurrent control flows at run time , Modeling concurrent control flows ,UML The concept of intersection and confluence is introduced in

11、 lane ： Divide the activities in the activity diagram into groups , Each group is assigned a business organization responsible for this group of activities , Namely object . In the activity chart , Swimlane distinguishes the object responsible for the activity , It clearly indicates which activities are performed by which objects , In the activity chart that contains the swimlane , Each activity can only belong to one lane

actual combat —— Computer room charging system

One 、 Log in to the computer room to judge

Two 、 Getting on and off the machine

3、 ... and 、 Overall swimlane diagram of the machine room

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