[Design View / Design Solution]
UML 2.0 Incrementally Improves Scalability And Architecture
Soon you’ll be able to take advantage of elaborated interfaces and ports, interaction fragments and operators, plus better modeling of behavior over time.
DESIGN VIEW is the summary of the complete DESIGN SOLUTION contributed article, which begins on Page 2.
There's much hoopla surrounding the upcoming UML 2.0 specification. Soon enough you will be able to take advantage of elaborated interfaces and ports, interaction fragments and operators, plus beter modeling of behavior over time. However, UML 2.0 is many months from being released in its final form—let alone being voted on and adopted. A number of questions are being raised about the spec due to conflicting reports. This article offers some answers.
Four related requests for proposals (RFPs) exist for the UML 2.0: Infrastructure, Object Constraint Language (OCL), XML Metadata Interchange (XMI), and Superstructure. The superstructure RFP is the one that most users (those who construct real models and build systems that work in the real world) will care about, since the proposal contains the most "user-visible" parts of UML 2.0.
Two main forces drive the RFP's requirements: scalability and architecture. Changes made for architecture in UML 2.0 primarily involve the structural (class) model, while changes for scalability are best seen in the improved sequence diagrams.
According to the RFP, UML 1.x notions of interface and architecture must be enhanced to support and simplify support for standard component frameworks and architectures. Moreover, data-flow modeling must be added, relationship semantics have to be clarified, and sequence diagrams need enhancing.
Discussion within the article focuses on structured classes, statechart inheritance, and sequence and timing diagrams. A series of figures help to illustrate these segments.
Though UML 2.0's final release is months away, some major features and characteristics are already known, giving users a preview to improved architectural modeling.
HIGHLIGHTS:
UML Superstructure
The superstructure RFP is driven by scalability and architecture. These concepts are important to define metaclasses that work well as they scale from small to large.
Statechart Inheritance
"Substitutability" is the crux of inheritance. That is, an instance of a subclass may be freely substituted for an instance of the superclass, and the system still makes sense and works.
Sequence Diagrams
UML 2.0's changes to sequence diagrams improve the diagrams' "spec-ness" (the ability to specify things) and their scalability.
Timing Diagrams
Sequence diagrams effectively show the sequence of service invocations, but they come up short as a view of actions over time. The author came up with more effective timing diagrams that were incorporated into UML 2.0.
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