Based on D. Galin , and R. Patton
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According to D. Galin
Software quality assurance is:
A systematic, planned set of actions necessary to provide
sufficient assurance that the software development process or
the maintenance process of a software system product conforms
to established functional technical requirements as well as with
the managerial requirements of keeping the schedule and
operating within the budgetary confines
According to the IEEE
Software quality assurance is:
1. A planned and systematic pattern of all actions
necessary to provide sufficient confidence that an item
or product conforms to established technical
requirements.
2. A set of activities designed to evaluate the process by
which the products are developed or manufactured.
(1) Assuring an acceptable level of confidence that the software
will conform to functional technical requirements.
A function is described as a set of inputs, the behavior (use case)
and outputs . Functional requirements may be calculations, data
manipulation and processing and other specific functionality that
define what a system is supposed to accomplish
Functional requirements are supported by non-functional
requirements, which enforce constraints on the design or
implementation (such as performance requirements, security, or
reliability).
Functional requirements are expressed in the form "system must
do <requirement>", while non-functional requirements are
"system shall be <requirement>".
The plan for implementing functional requirements is detailed in
the system design. The plan for implementing non-functional
requirements is detailed in the system architecture.
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(2) Assuring an acceptable level of confidence that the software
will conform to managerial scheduling and budgetary
requirements.
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The logical design of a system relates to an
abstract representation of the data flows,
inputs and outputs of the system
Often conducted via modelling, using an
over-abstract (and sometimes graphical)
model of the actual system. Logical design
includes ER Diagrams
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The physical design relate to the actual input and
output processes of the system.
In terms of how data is input into a system, how
it is verified/authenticated, how it is processed,
and how it is displayed as In Physical design, the
following requirements about the system are
decided.
Input requirement,
Output requirements,
Storage requirements,
Processing Requirements,
System control and backup or recovery.
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(1) Assuring an acceptable level of confidence that the software
maintenance activities will conform to the functional
technical requirements.
(2) Assuring an acceptable level of confidence that the software
maintenance activities will conform to managerial
scheduling and budgetary requirements.
The importance of software maintenance
A study by Lientz and Swanson, categorized maintenance
activities into four classes:
Adaptive – modifying the system to cope with changes in the
software environment (Ex. DBMS, OS)
Perfective – implementing new or changed user requirements
which concern functional enhancements to the software
Corrective – diagnosing and fixing errors, possibly ones found by
users
Preventive – increasing software maintainability or reliability to
prevent problems in the future
● Know what you are doing
● Know what you should be doing
● Know how to measure the difference
1.Know what you are doing
– understand what is being built, how it is
being built and what it currently does
 suppose a software development process
with management structure (milestones,
scheduling) reporting policies, tracking
2. Know what you should be doing
– having explicit requirements and
specifications
– presume a software development process
with requirements analysis, acceptance tests,
frequent user feedback
3. Know how to measure the difference
– having explicit measures comparing what is
being done from what should be done
Complementary methods:
● formal methods – verify mathematically specified
properties
● testing – explicit input to exercise software and
check for expected output
● inspections – human examination of
requirements, design, code, ... based on
checklists
SQA includes
● Verification
– are we building the product right ?
– performed at the end of a phase to ensure that
requirements established during previous phase
have been met
● Validation
– are we building the right product ?
– performed at the end of the development
process to ensure compliance with product
requirements
REQUIREMENT
ARCHITECTING
Verification
Verification
LOW DESIGN
Verification
CODING
Verification
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Reliability Requirements
Reliability is to have your system available in the worst possible scenario. To
achieve these goals exist redundancy that provides data reliability, and fault
tolerance that provides disk reliability.
Portability Requirements
System can be easily and quickly docked to a new specified environment when
necessary.
Usability Requirements
Usability involves satisfaction and learnability, because if the common user can
not learn naturally what the system can and can not do then he will not use it.
Note : without usability the whole system has no meaning because no one will use
it
Efficiency Requirements
It comprises two type:
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Space Requirements, it involves the space the system or application could fill in its life, for
example the amount of disk space the database will occupy in the first year, or maybe the
minimun available memory space need it to correctly perform.
Performance Requirements, it includes the application reponse time, for example some
applications would need to have a minimum response time of 0.5 seconds. With this
requirement you have to consider how the system will change overtime.
Nietho,J,
http://www.jnieto.org/article/product_requirements_in_software_engineering