Software Analysis and Design Process
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Chapter
Chapter
2
2
Introduction
Introduction
Software Analysis and Design
0721322
Requirements
Requirements
Analysis
Analysis
•
The
purpose
of
requirements analysis
is to
produce
an
analysis
or
a logical
model
of the desired
system
.
•
The
analysis model
can be seen as a
bridge
between
the
requirements model
and the
design model
.
Analysis modeling
represents the user's requirements by depicting the software in three
different domains: information domain, functional domain, and behavioral domain.
A
model
developed
to
learn
all aspects of a problem domain
to
determine
the best way to
solve a specific set of user needs. Ex. Descriptive, diagnostic, predictive., prescriptive.
Requirements modeling
is the process used in software development projects where
requirements and solutions constantly evolve through collaborative efforts and
teamwork.
A
design model
in software engineering is an object-based picture or pictures that
represent the use cases for a system. Or to put it another way, it's
the
means
to
describe
a
system's implementation and source code in a diagrammatic fashion
.
Requirements
Requirements
Analysis
Analysis
vs
vs
Design
Design
•
Software
design
is the process of envisioning and defining software
solutions to one or more sets of problems.
•
During Requirements a
Use-Case Model
is
developed
to
capture
the
requirements of the system
.
•
Requirements
analysis
focuses
on
understanding
the
requirements
of the
desired
system
to
produce a high-level specification
that
describes
what
the
system should do.
•
During
Design
, we should specify clearly
how
the system
should be
constructed
to
satisfy
the
requirements
.
Transition
Transition
from
from
Requirements
Requirements
to
to
Design
Design
•
Use-case
Realization
From
Use-cases
to
Analysis model
Analysis model
includes
a “
Conceptual
” Class diagram, in addition to other UML
diagrams.
A
conceptual model
is the model of an application that the designers want users to understand
Transition from Requirements to Design
Transition from Requirements to Design
Object-oriented analysis and design using UML, 4
th
edition
Simon Bennett, Steve McRobb and Ray Farmer
Design
Design
•
We
cannot
move
directly
from
requirements
(high level) to
implementation
(low
level)
•
The
purpose
of
design phase
is to
produce
a
detailed
specification of the desired
system
that
satisfies
the
requirements
.
•
Programmers
translate
the
design document
into a
programming language
to
build
the desired
system
.
Design
Design
•
Architectural Design (called system design)
•
Interface Design
•
Database Design
•
Algorithm Design
Application Design
o
Refining the Analysis model
Design
Design
Levels
Levels
•
Architectural Design (sometimes called System Design)
•
High-Level Design
•
Low-Level Design (sometimes called Detailed Design)
Software design typically involves 2 levels of design – namely architectural and detailed design.
•
The
Architectural design
specifies the basic components of the software system such as user
interface, database, reporting module, etc. often using tools such as
Data Flow Diagrams
(DFD)
and
Entity-Relation Diagrams
(ERD).
•
Detailed design elaborates on each of these components in terms of tables and fields in the
database, layout and data to be displayed on the graphical user interface, and often pseudo-
code for any data analysis modules
Software Design Principles
Software Design Principles
•
Correctness
Software design must satisfy the requirements
.
Many correct designs may exist
How to know that a design is correct?
Formal approaches
Informal approaches
Software Design Principles
Software Design Principles
•
Correctness
Informal approaches require that the design must be:
Readable (to enhance understanding)
Modular (to deal with complexity)
Software Design Principles
Software Design Principles
•
Robustness
The degree to which a system or component can function correctly in the presence of
invalid inputs or stressful environmental conditions (IEEE).
Invalid inputs
could come from users, data communication or function calls.
Some errors might be caused by development team ( for example in design,
implementation, etc.)
Software Design Principles
Software Design Principles
•
Robustness
How to ensure robustness?
Verifying inputs
( type checking, preconditions )
Initializing variables or objects
instead
of relying on
default values
in programming
languages.
Exceptions handling
.
Software Design Principles
Software Design Principles
•
Flexibility
Adding more functionalities ( adding a function, a class , etc.)
Changing functionalities
Software Design Principles
Software Design Principles
•
Reusability
Could be done on different levels:
F
unctions, classes, components, design patterns, frameworks, etc.
Software Design Principles
Software Design Principles
•
Reusability
Software Design Principles
Software Design Principles
•
Efficiency
I
n time (algorithms complexity)
In space
Software analysis and design involve a systematic approach to understanding user requirements, creating logical models, and transitioning to detailed design specifications. Requirements analysis focuses on capturing system requirements, while design translates these requirements into implementation plans. The process involves modeling in information, functional, and behavioral domains, as well as transitioning from use cases to design realization through UML diagrams. Object-oriented analysis and design using UML play a crucial role in this process.
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Presentation Transcript
Chapter 2 Introduction Software Analysis and Design 0721322
Requirements Analysis The purpose of requirements analysis is to produce an analysis or a logical model of the desired system. The analysis model can be seen as a bridge between the requirements model and the design model. Analysis modeling represents the user's requirements by depicting the software in three different domains: information domain, functional domain, and behavioral domain. A model developed to learn all aspects of a problem domain to determine the best way to solve a specific set of user needs. Ex. Descriptive, diagnostic, predictive., prescriptive. Requirements modeling is the process used in software development projects where requirements and solutions constantly evolve through collaborative efforts and teamwork. A design model in software engineering is an object-based picture or pictures that represent the use cases for a system. Or to put it another way, it's the means to describea system's implementation and source code in a diagrammatic fashion.
Requirements Analysis vs Design Software design is the process of envisioning and defining software solutions to one or more sets of problems. During Requirements a Use-Case Model is developed to capture the requirements of the system. Requirements analysis focuses on understanding the requirements of the desired system to produce a high-level specification that describes whatthe system should do. During Design, we should specify clearly how the system should be constructedto satisfy the requirements.
Transition from Requirements to Design Use-case Realization From Use-cases to Analysis model Analysis model includes a Conceptual Class diagram, in addition to other UML diagrams. A conceptual model is the model of an application that the designers want users to understand
Transition from Requirements to Design Object-oriented analysis and design using UML, 4th edition Simon Bennett, Steve McRobb and Ray Farmer
Design We cannot move directly from requirements (high level) to implementation (low level) The purpose of design phase is to produce a detailed specification of the desired system that satisfies the requirements. Programmers translate the design document into a programming language to build the desired system.
Design Architectural Design (called system design) Interface Design Database Design Algorithm Design Application Design o Refining the Analysis model
Design Levels Architectural Design (sometimes called System Design) High-Level Design Low-Level Design (sometimes called Detailed Design) Software design typically involves 2 levels of design namely architectural and detailed design. The Architectural design specifies the basic components of the software system such as user interface, database, reporting module, etc. often using tools such as Data Flow Diagrams (DFD) and Entity-Relation Diagrams (ERD). Detailed design elaborates on each of these components in terms of tables and fields in the database, layout and data to be displayed on the graphical user interface, and often pseudo- code for any data analysis modules
Software Design Principles Correctness Software design must satisfy the requirements. Many correct designs may exist How to know that a design is correct? Formal approaches Informal approaches
Software Design Principles Correctness Informal approaches require that the design must be: Readable (to enhance understanding) Modular (to deal with complexity)
Software Design Principles Robustness The degree to which a system or component can function correctly in the presence of invalid inputs or stressful environmental conditions (IEEE). Invalid inputs could come from users, data communication or function calls. Some errors might be caused by development team ( for example in design, implementation, etc.)
Software Design Principles Robustness How to ensure robustness? Verifying inputs ( type checking, preconditions ) Initializing variables or objects instead of relying on default values in programming languages. Exceptions handling.
Software Design Principles Flexibility Adding more functionalities ( adding a function, a class , etc.) Changing functionalities
Software Design Principles Reusability Could be done on different levels: Functions, classes, components, design patterns, frameworks, etc.
Software Design Principles Reusability
Software Design Principles Efficiency In time (algorithms complexity) In space
