Nine requirements use case analysis: Sequence diagram

Author: Zhang Keqiang author Weibo: Zhang Keqiang-Agile 307

Sequence diagram, also known as time series diagram, sequence diagram, English name sequence Diagram. In the Jacobson use case analysis approach, it is encouraged to express using a variety of graphs, but the sequence diagram is not explicitly mentioned. The Coburn use Case analysis method focuses on the structured/semi-structured text use case, emphasizes the text format based on the target, and does little to the UML diagrams.

In Rup and Ooad, the most basic positioning of UML sequence diagrams is to identify the transfer of information between classes and classes, which is the best place to identify the methods of a class. It plays a huge role after it has been preliminarily identified by the use case. A sequence diagram is a type of interaction diagram (interaction diagram) that can be converted into a assistance diagram (communication diagram). Using sequence diagram settings, you can precisely define the methods of classes and classes to generate source code.

In Pangayu's "Software Method" [7], the activity diagram and sequence diagram are compared, advocating the use of sequence diagram to express the business, called the business sequence diagram, and then based on the business sequence diagram to identify the system use case (different from the business use case, that is, the use case of this article). You can find that when working with multiple business roles, the sequence diagram does have the same expressiveness as the activity diagram.

Then, if the sequence diagram is used in the use case specification, what will be the scene.

Images from the Web

You can see that the content of the sequence diagram is the same as the basic flow text, more intuitive, but obviously needs more time, and does not fully explain the details of the interaction, after all, in the picture is not appropriate to hit the dense word. More critical of the above diagram is the "bank host", which is beyond the scope of a single use case.

In general, sequence diagrams are not a standard configuration of use cases, and using sequence diagrams in a use case specification can better present the flow of events, but it will take more time, and if other roles and other use cases are considered in a single use case, then more time is spent and may be duplicated with the previous business analysis and possibly with subsequent design analysis.

In writing an effective use case, it is clear that it is inappropriate to draw a sequence diagram in a use case specification.
more related articles requirements One use case analysis: Exception flow

Two requirements use case analysis: Level setting
Three requirements use case analysis: supplementary statute

Four requirements use case analysis: Business rules

Demand use case analysis: the rational system of business use cases

Requirements use case analysis of the six: business use case of the Department of the Bourne requirements use case Analysis VII: Business use case summary

Requirement use case Analysis eight: use case granularity