UML sequence diagram (sequence diagram) sequence DIAGRAM_UML

1. What is a sequence diagram

is an interaction diagram that emphasizes the time order of messages. A sequence diagram describes the interaction between classes and classes in a class system, and it models these interactions as message exchanges. A sequence diagram is a model that describes how objects collaborate over time with certain behaviors. (emphasis is on the time Order of messages) 2. function of sequence diagram

1. A sequence diagram is used to represent the order of behavior in a use case. When performing a routine last, each message in the sequence diagram corresponds to a class action or an event that causes a transformation in the state machine.
2. The sequence diagram shows the interactions between objects that occur in the event flow of a scene or use case. The sequence diagram belongs to Dynamic modeling.
3. The emphasis of the sequence diagram is on the message sequence, that is, describing how the message is sent and received between objects. Represents the chronological order in which messages are routed between objects.
4. The improvement of the class diagram. 3. Things in a sequence diagram

Message symbol:
1. Simple message: Solid line + regular arrows. Is the transfer of the control flow from one object to another.
2. Asynchronous message: Solid line + half arrow. After the message is sent, the sending object can continue its operation without waiting for the receiving object to reply.
3. Sync message: Solid line + solid triangle representation. After the message is issued, the sending object must wait for the receiving object to reply before continuing its operation. 4. Examples

Or for example, we operate the database under the command line of a computer. This includes logging in to the database and then doing an incremental check.

5. The difference between the collaboration diagram and the sequence diagram and the relationship between the collaboration diagram and the sequence diagram show the interaction between the objects, but they have different emphases. The sequence diagram clearly represents the time sequence (emphasis time) in the interaction, but does not explicitly represent the relationship between objects. A collaboration diagram clearly represents the relationship between objects (accent space), but the chronological order must be obtained from the order number. collaboration diagrams and sequence diagrams can be transformed into each other.