Transcript Document 7333537

Software Requirements
Software Requirement Specifications
have been used the traditional
starting point for software
development
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Requirement Specification
 The
goal of a requirement methodology
is to produce a good requirement
specification.
 The goal of a requirement specification
is to be able to answer questions about
the behavior of the proposed system.
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SRS - ansi/ieee std 830
 Revised
1993
 http://stdsbbs.ieee.org
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SRS Prototype Outline
 1.
Introduction
 2. Overall Description
 3. Specific Requirements
 appendices
 index
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Introduction (1)
 1.1
Purpose
– delineate the purpose of the SRS and the
intended audience
 1.2
Scope
– identify products, explain what product will
and will not do, describe the application of the
software including benefits, objectives, goals
requirements
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Introduction (2)
 1.3
Definitions
– all terms, acronyms and abbreviations
 1.4
References
– all documents referenced elsewhere
 1.5
Overview
– describe what rest of document contains
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Overall Description (1)
 2.1
Product Perspective
– put product into perspective with other products
– block diagram of the larger system
– various constraints
» e.g. system interfaces, user interfaces (e.g. screen
formats, timing), hardware interfaces, software (e.g.
versions of interfaced software), memory constraints,
operations (e.g. modes of operations), site adaptation
constraints
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Overall Description (2)
 2.2
Product Functions
– summary of major functions
 2.3
User characteristics
– educational level, experience, technical
expertise
 2.4
Constraints
– any other, e.g. regulatory
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Overall Description (3)
 2.5 Assumptions
and Dependencies
– e.g. assumptions that if not true would require
changes to the requirements
 2.6 Apportioning
of Requirements
– identify requirements that may be delayed to
future versions
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Group Task
 Complete
sections 1 and 2 of an SRS for
the grocery store inventory problem
 Turn
requirements
/ Fax in
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Grand View of Specification
Not all methodologies use all parts
DD contains name,
type,semantics of all
data used or produced
ER shows relations
between data
Object Model
ST shows
behavior of
system in terms
of states and
sequencing
State Model
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Data
Dictionary
State-Transition
Diagram
Data Dictionary
DFD shows data and
the processes that use
and produce data
Sequence Diagram
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Payroll example
tcard
validate
tcard
many of the
data flows have
been left off for
simplicity
A0
requirements
produce reports
reports
validdata
calc
pay
pay
data
personnel files
update
files
Calculate Pay
G1
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Object Model
person
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State Diagrams
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Sequence Diagrams (Scenarios)
B
A
x
D
C
y
z
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Section 3 - specific requirements
 “This
section of the SRS should contain all
the software requirements to a level of
detail sufficient to enable designers to
design a system to satisfy those
requirements, and testers to test that the
system satisfies those requirements.”
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Section 3 - continued
 “These
requirements should include at a
minimum a description of every input
(stimulus) into the system, every output
(response) from the system and all
functions performed by the system in
response to an input or in support of an
output”
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Section 3 - by object (1)
 3.1
–
–
–
–
External interface requirements
3.1.1 user interfaces
3.1.2 hardware interfaces
3.1.3 software interfaces
3.1.4 communication interfaces
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Section 3 - by object (2)
 3.2
Classes/Objects
– 3.2.n Class/Object n
» 3.2.n.1 Attributes

3.2.n.1.m attribute m
» 3.2.n.2 Functions

3.2.n.2.l function l
» 3.2.n.3 Messages
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Section 3 - by object (3)
 3.3
Performance requirements
 3.4 Design Constraints
 3.5 Software system attributes
 3.6 Other requirements
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Group Task
 Complete
section 3 of an SRS for the
grocery store inventory problem.
 Turn
requirements
in / Fax in
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