OOAD: Overly Abstract Design
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OOAD: Overly Abstract Design
OOAD: Overly Abstract Design
1月10日修改
Requirements Engineering
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One element of the Waterfall Model
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Requirements Engineering - Design - Implementation - Testing - Maintenance
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Model of the system: describing a system at a high level of abstraction
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Who designed OO notations?
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Grady Booch (BOOCH)
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Jim Rumbaugh (OML: Object Modeling Language)
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Ivar Jacobson (OOSE: Object Oriented Software Engineering)
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Who won Turing Award for software engineering?
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Fred Brooks (Mentioned, for The Mythical Man-Month / No Silver Bullet)
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Robert Floyd
Unified Modeling Language (UML)
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It is the "union" of all modeling languages, many loosely related styles under one roof
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Nearly everything in UML is optional
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Static Modeling: Captures the fixed, code-level stuff
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Class Diagram
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Behavioral Modeling: Captures the dynamic execution of a system
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Use-case Diagram
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Interaction diagrams, e.g. Sequence Diagram
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Statechart Diagram
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Activity Diagram
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The bad things about UML:
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A set of many ideas; visual syntax does not scale well; semantics not completely clear
Use-case Diagram
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Captures the requirements of a system from the user's perspective, and is at a higher level of abstraction than other UML elements
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Use case: a particular piece of functionality that the system must provide
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May include supplemental information: entry / exit conditions, nonfunctional requirements
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Marks
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Actor (stick figures): a role that a user takes when invoking a use case
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A single user may be represented by multiple actors
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Use cases (ovals): edges from actor to use case showing that the actor is involved in that use case
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Just an "association" relationship, e.g. Normal user cannot cancel session, but refund is related to him, so we also need to link to them other than the admin
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Relationships in Use-case
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Generalization, e.g. Push train button is a specialization of push button
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Extension is an exceptional variation of a use case, e.g. Derail is exceptional for riding
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Inclusion, e.g. Push button included in ride
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Note: generalization and extend point to parent (I extend my parent), while inclusion point to the children (I include my child)
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An example use-case diagram
Statechart Diagram
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Shows the various stages of an entity during its lifetime, to show the state transitions
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Marks
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State: a condition of a modeled entity