on to object design 徐迎晓 [email protected] 复旦大学软件学院 2005.11
TRANSCRIPT
OutlineAgile Modeling and UML
UML Case Tools
Limit time spent drawing
Dynamic and Static Models
CRC Cards
Agile Modeling and UMLTwo of the aims of Agile modeling:Reduce drawing overheadModel to understand and communicate
This is a change from a view of modeling as documentation. In a era of rapid change, documentation tends to have minimal value.
More Agile PrinciplesModeling with others
Create several models in parallel
Use temporary models such as diagrams on white boards
Digital photographs of white boards can be shared on a wiki. (See www.twiki.org)
Fig. 14.1
OutlineAgile Modeling and UML
UML Case Tools
Limit time spent drawing
Dynamic and Static Models
CRC Cards
UML Case ToolsYou can also do agile modeling with UML case tools like Rational Rose, or one that comes with a popular IDE such as Eclipse or Visual Studio.
Choose a tool that can read your code and reverse engineer it to create diagrams from your code.
Switch back and forth from diagramming to reverse engineering.
OutlineAgile Modeling and UML
UML Case Tools
Limit time spent drawing
Dynamic and Static Models
CRC Cards
Limit time spent drawingA few hours or at most one day of diagramming should do most of the work for a three week iteration.
Occasional short sessions of modeling during the iteration can clarify any concepts that still need to be understood.
OutlineAgile Modeling and UML
UML Case Tools
Limit time spent drawing
Dynamic and Static Models
CRC Cards
Dynamic and Static Models
Dynamic models such as interaction diagrams (sequence or communication diagrams) help design logic, code behavior, and method bodies.
Static Models such as class diagrams help define packages, class names, attributes, and method signatures.
Switch back and forth during modeling sessions.
Dynamic ModelsMost of the challenging, interesting, and useful design work comes during dynamic modeling. The interaction diagrams are typically where we apply design patterns such as the GRASP patterns.
If the most important skill in object design is assigning behavior to objects, this is when it usually takes place.
Dynamic Models (continued)
Dynamic UML models include sequence, communication, state machine and deployment diagrams.
Static ModelsIf behavior is designed during dynamic modeling, it is the static models, such as the class diagrams, which give the overall structure to our software, and allow us to divide the work into manageable and maintainable chunks.
Static UML models include class, package, and deployment diagrams.
Design Skill, not UML skillUML is only an ancillary tool to object design. The real skill is the design, not the diagramming.
Seeking a software design job because you are good at making UML diagrams is like seeking a career as a novelist because you have good penmanship.
OutlineAgile Modeling and UML
UML Case Tools
Limit time spent drawing
Dynamic and Static Models
CRC Cards
CRC CardsAn alternative to UML Object Design is the Class, Responsibility, Collaboration cards popularized by Kent Beck in eXtreme Programming.
There are some brief examples in the text, but you should get a book on eXtreme Programming or go to a Web site if you are interested.
Fig. 14.2
Fig. 14.3