Sequence diagram （Sequence Diagram） There are many meanings and usages . In biology , Sequence diagram can be referred to as the physical map of nucleotide sequence on genetic material , It is the most basic work in the human genome project , It's the highest level of the human genome at the molecular level , The most detailed physical diagram , The total length was determined to be 1M, By 30 A genome of 100 million pairs of nucleotides DNA sequence . In software engineering , Sequence diagram is a representation of object interaction .
UML There are two kinds of models ： Dynamic model and static model . Use case diagram , Both class and object diagrams are UML Static structure model in . And in the UML One of the system dynamic models is interactive view , It describes the sequential relationship between the roles that perform system functions to pass messages to each other . Sequence diagram is a form of interactive view .
Sequence diagrams are primarily used to follow the sequence in which interactions occur , Show these interactions between objects . It's like a class diagram , Developers generally think that sequence diagrams only make sense to them . however , Business people in an organization will find that , Sequence diagrams show how different business objects interact , It's useful for communicating how current business is going . In addition to recording the organization's current events , A business level sequence diagram can be used as a requirements document , Delivering requirements for a future system . In the requirements phase of the project , Analysts can do this by providing a more formal level of expression , Take use cases to the next level .
Sequence diagram （Sequence Diagram） By object （Object）, lifeline （Lifeline）, activation （Activation）, news （Messages）, It is composed of branches and subordinate flows