1. NGSSC/OOSP/OOAD. OOAD part III. On OO methodologies,. UML,. Design
patterns. NGSSC/OOSP/OOAD. On OO methodologies. Historical perspectives.
Why do we model?
On OO methodologies Historical perspectives
OOAD part III On OO methodologies, UML, Design patterns
Methodologies (OOAD) • 1991 Booch • 1991 OMT Rumbaugh et al • 1992 OOSE Jacobsen • 1995 UML 0.9 • 2002 UML 1.4
Languages: • 1969 Simula • 1972 Smalltalk • 1985 C++ • 1995 Java
NGSSC/OOSP/OOAD
NGSSC/OOSP/OOAD
OOAD motivation
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NGSSC/OOSP/OOAD
• OOAD notation is graphical: 1 bitmap = 1 megaword.
Provide structure for problem solving Experiment to explore multiple solutions Furnish abstractions to manage complexity Reduce time-to-market for business problem solutions • Decrease development costs • Manage the risk of mistakes Remark: This page and several others in this presentation, is inspired by OMG tutorials on UML by Kobryn et al.
NGSSC/OOSP/OOAD
UML • A graphical language for – specifying – visualizing – constructing – documenting
• An OOAD methodology provides a and a . • There are many different processes, but UML represents the standard for notation.
• Analysis and design was important also before OO programming languages. • But OOP requires special analysis and design. • Earlier AD often used a “waterfall” approach. • Earlier AD often used different notations in A and D (and P). • OOAD provides a more incremental approach. • OOAD avoids “semantic gap” because notation is similar in both A and D (and P).
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• “Choose your own process, but use ~UML as a notation” NGSSC/OOSP/OOAD
the artifacts of software systems • OMG UML 1.4 Specification: • • • •
UML Summary UML Semantics UML Notation Guide Object Constraint Language
NGSSC/OOSP/OOAD
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Diagram: Classifier View
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– cf. elements, bonds and molecules in chemistry – cf. components, connectors and circuit boards in hardware NGSSC/OOSP/OOAD
Well-Formedness Rules • Well-formed: indicates that a model or model fragment adheres to all semantic and syntactic rules that apply to it. • UML specifies rules for: • • • • •
naming scoping visibility integrity execution (limited)
• However, during iterative, incremental development it is expected that models will be incomplete and inconsistent. NGSSC/OOSP/OOAD
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Well-Formedness Rules (cont’d) • Example of semantic rule: Class [1] • English: If a Class is concrete, all the Operations of the Class should have a realizing Method in the full descriptor. • OCL: not self.isAbstract implies self.allOperations-> forAll (op | self.allMethods-> exists (m | m.specification-> includes(op)))
NGSSC/OOSP/OOAD
Well-Formedness Rules (cont’d) • Example of syntactic rules: Class • Basic Notation: A class is drawn as a solid-outline rectangle with three compartments separated by horizontal lines. • Presentation Option: Either or both of the attribute and operation compartments may be suppressed.
• Example of syntactic guideline: Class • Style Guideline: Begin class names with an uppercase letter. NGSSC/OOSP/OOAD
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a relationship between two or more classifiers that involves connections among their instances. A special form of association that specifies a whole-part relationship between the aggregate (whole) and the component part. a taxonomic relationship between a more general and a more specific element. a relationship between two modeling elements, in which a change to one modeling element (the independent element) will affect the other modeling element (the dependent element).
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