14.3. On to Object Design
During object design, a logical solution based on the object-oriented paradigm is developed. The heart of this solution is the creation of interaction diagrams, which illustrate how objects collaborate to fulfill the requirements.
After—or in parallel with—drawing interaction diagrams, (design) class diagrams can be drawn. These summarize the definition of the software classes (and interfaces) that are to be implemented in software.
In terms of the UP, these artifacts are part of the Design Model.
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In practice, the creation of interaction and class diagrams happens in parallel and synergistically, but their introduction is linear in this case study, for simplicity and clarity. |
The Importance of Object Design Skill vs. UML Notation Skill
The following chapters explore the creation of these artifacts, or more precisely, the object design skills underlying their creation. What is important is knowing how to think and design in objects, which is a very different and much more important ability than knowing UML diagramming notation. At the same time, a standard visual language is great, and thus the required UML notation to support the design work is presented.
Of the two artifacts that will be explored, interactions diagrams are the most important—from the point of view of developing a good design—and require the greatest degree of creative effort. The creation of interaction diagrams requires the application of principles for assigning responsibilities and the use of design principles and patterns. Therefore, the emphasis of the following chapters is on these principles and patterns in object design.
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Object Design Skill vs. UML Notation Skill Drawing UML interaction diagrams is a reflection of making decisions about the object design. The object design skills are what really matter, rather than knowing how to draw UML diagrams. Fundamental object design requires knowledge of:
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