# Systematic OO Programming with Axiomatic Design by wuxiangyu

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```									Systematic OO Programming
with Axiomatic Design
Sung-Hee Do &
Nam P. Suh,
Axiomatic Design
Axiomatic Design
•   Offers a systematic and orderly way to
proceed through the software development
process
•   Provides for a methodology that ensures
developers make the best design decisions by
providing decision-making criteria in the form
of 2 axioms:
The independence axiom
The information axiom
Independence Axiom
• Suggests that the best designs maintain
the independence of the functional
requirements, ensuring that the design can
achieve each function without
(Coupling)
Information Axiom
• Suggests that the best designs minimize
their information content. Thus the
solution with the greatest likelihood of
success is the simplest solution.
Benefits of Axiomatic Design
• The quality of design can be determined
upon the degree to which it satisfies the
defined functional requirements;
• The design ensures that each function is
satisfied independently and that coupling
does not occur

(con’t.)
Benefits of Axiomatic Design
(con’t.)
• Job assignment and team management is
easier because they can use the system
architecture diagram to assign tasks and
define the inter-relationships between
various modules or classes
• Software change orders can be handled
quickly and easily because the system
architecture identifies the modules
affected by a change
The Process…
Investigate customer attributes to
discover customer’s needs.
Note these needs and determine the
design’s functional requirements (FRs)
must this design do to satisfy the
customers’ needs?”
and record the results as FRs in the
left column of a design matrix.
(here)
Developers record the design
parameters (DPs)- physical solutions
that satisfy each functional
requirement.

More than one design DP may satisfy
each FR, but the information axiom
will help determine the best solution.

This process is recorded across
the top of the design matrix.
Developers may indicate a relationship between the FRs and the DPs with an
X in the matrix or with an equation. The matrix checks that each DP satisfies
only one FR.

Developers decompose the design, working through each part to determine
the subfunctional requirements and subdesign of their previous design
until they’ve completed the entire design.

Axiomatic development pushes the
development team to define the
problem explicitly, envisioning the
entire design before writing a single
line of code.
Axiomatic Development Process
Axiomatic Design Example
The authors make use of a case study to
illustrate the effectiveness of axiomatic
design. The Acclaro design software is
the first implementation of a software
design package using axiomatic design
principles.
State tasks in terms of what the software must accomplish at the highest level.
Highest level FR – “to help developers succeed with software design”.
Find associated DPs & choose most feasible solution – “create axiomatic design
software”
Define next level of FRs and DPs
P in the leftmost column represents the parent level; items in numbered rows
below it represent highest level DPs and FRs
Continue from system level down to individual modules in increasing specific
detail until the design is decomposed into manageable pieces.
The matrix tracks decomposition; ensuring that DPs satisfy the FRs and are
not coupled.
Fourth level branch of Acclaro
X’s represent specific functions.
Outmost FRs and DPs are parents.

Numbers are assigned to the first level
that further define the parent level. Sub
FRs and Sub DPs acquire additional
numbers.

Compare these numbers with those in
Table1. (Relationship)
Module 1141 excerpt. (4th level branch)
-Outermost layer is 1141, next deeper is
11412.
-Module 1141 has sub-module 11411-
Module 11412 is five layers deep
-Only diagonal X’s describe independence
of FR-DP relationships (ie 114121 and
114122 are independent of one another)
-Module 114123 is decoupled- its
impacted by 114121 and 114122.
114123 only after making those for
114121 & 112122.
Corresponding system architecture for example design matrix. Circled S’s
represent summations of modules; the circled C’s represent control points that
indicate one step must precede the other.
System architecture
• Serves as a graphical representation of
the matrix
• Gives order in which to make design
decisions
• Indicates how those decisions will impact
other design functions
Development Ordering
• Core functions are diagonal matrix X’s and
should be developed along the diagonal in
order
• Off-diagonal terms do not represent core
functions-but are considered in
development
• The matrix helps developers establish and
organize the relationships
Object Orientation
• DP leaves can represent attributes, methods, or
arguments of a specific class
• One or two levels up, the DPs can also be
defined as a class combining the leaves below.
• Once classes are defined, developers can
define attributes and operations, then create
interfaces by establishing relationships bewteen
objects and operations, using the design
matrices.
???Questions???

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