Chapter IV
The use case mode is to write a quality flag of a set of good use cases.
4.1 SharedClearVision (Visiting Consensus)
Lack of clear system vision may lead to an indecisive opinion, and it may soon make the project will be paralyzed.
the reason:
Time stress may make people's premature development system, their work is based on the wrong basis, so that it is very expensive to enter the right track.
The build staff has a natural tendency to extend system scope;
There are some mutual conflicts between the people;
The project goals are not clear;
There is a lack of communication between developers;
and so:
Prepare a statement clearly describe the system objectives to ensure their support for organization's mission and distribute them directly to everyone who participates in the project.
Vision statements should include:
System objective;
• The problem will be solved;
• The problem does not solve;
Who is the public?
• How system will benefit the public;
4.2 Visibleboundary (visible boundary)
If you don't know the boundary of the system, the system's scope will grow in an uncontrollable manner.
the reason:
There are different perspectives for system boundaries.
Defining a bad boundary will result in a range of creep, developers like to add some features that will not give the system;
Some people think that it is unnecessary when defining the boundary;
and so:
By listing people and equipment interacting with the system, a visible boundary is established between the system and its environment;
The early stage of development, because the vision of the system is not clear, the system boundary may be blurred, first determine a system boundary, become a document, and then the development of Spiraldevelopment.
Context:
system
Terminator
Terminator
Terminator
Terminator
4.3 ClearCastOfchaacters (clear recognition role)
If you only analyze the user's users, ignore the roles they play in the system, you might miss the behavior of important systems or introduce redundancy.
the reason:
The system must meet the needs of their users and protect their interests, such systems are useful;
Tie service and some users can make the system very dead;
The narrow focus or vision of the main expert expert may make us leaken the service required by the user;
Place the focus on the user may enable us to implement the details, not the understanding of the services they need to users;
Time pressure and weight meter encourage us only to analyze users;
and so:
Identifying the participants of the system must interact with each participant and the role played in each participant and system, and clearly describe each participant.
4.4 UserValuedTransactions
If the system does not provide valuable services for their users, the system is not supported by the purpose and targets of the system vision, the system is not perfect.
the reason:
A well-written use case should clearly accurately describe the basic features provided by the system, which enables customers to see it before building the system to determine if the system provides services they think that valuable services;
Identifying a low-level transaction is easy, but identifying valuable services;
In a high-level level, you can guarantee the relative stability of use;
Written in too high levels, useless system developers;
Write a use case on too low level; it is difficult to understand the system from a high level;
and so:
Identification system provides participants with valuable services to meet their business purposes; avoid form-based use cases;
4.5 EverunfoldingStory
The steps required to describe the behavior of the system have exceeded all readers' memories and interests.
the reason:
Different from different perspectives;
Each usage may have many readers and many ways, they need different detailed levels;
Writing cases in multiple hierarchies will make people feel confusing;
The writer needs to follow a principle to organize the needs;
and so:
The form of a group of uses is organized as a layered story, you can get more details, or fold it to hide detail, show more context;
Three levels:
l Summary: You need to use multiple user target sessions;
l User Target Level: Meet the currently particular value goals of the primary participants, generally executed by a primary participant;
L Subfunctional level: Partial objective that meets user target levels or another sub-function;
