Lecture No-14.pptx Lecture No-14.pptx xx

REQUIREMENTS VALIDATION – I
LECTURE NO-14
1

TODAY’S TOPICS
2
• Requirements validation
• Validation techniques

REQUIREMENTS ENGINEERING
PROCESS
3
Requirements
Elicitation
Requirements
Analysis and
Negotiation
Requirements
Specification
Requirements
Validation
User Needs,
Domain Information,
Existing System
Information, Regulations,
Standards, Etc.
Requirements
Document
Agreed
Requirements

VALIDATION OBJECTIVES
4
• Certifies that the requirements document is an
acceptable description of the system to be implemented
• Checks a requirements document for
– Completeness and consistency
– Conformance to standards
– Requirements conflicts
– Technical errors
– Ambiguous requirements

ANALYSIS AND VALIDATION
5
• Analysis works with raw requirements as elicited
from the system stakeholders
– “Have we got the right requirements” is the key
question to be answered at this stage
• Validation works with a final draft of the
requirements document i.e., with negotiated and
agreed requirements
– “Have we got the requirements right” is the key
question to be answered at this stage

VALIDATION INPUTS AND
OUTPUTS
6
Requirements
Validation
Requirements
document
Organizational
knowledge
Organizational
standards
List of problems
Agreed actions

REQUIREMENTS DOCUMENT
7
• Should be a complete version of the
document, not an unfinished draft.
Formatted and organized according to
organizational standards

ORGANIZATIONAL KNOWLEDGE
8
• Knowledge, often implicit, of the
organization which may be used to
judge the realism of the requirements

ORGANIZATIONAL STANDARDS
9
• Local standards e.g. for the
organization of the requirements
document

LIST OF PROBLEMS
10
• List of discovered problems in the
requirements document

AGREED ACTIONS
• List of agreed actions in response to
requirements problems. Some problems
may have several corrective actions; some
problems may have no associated actions
11

REQUIREMENTS REVIEWS
12
• A group of people read and analyze the
requirements, look for problems, meet
and discuss the problems and agree on
actions to address these problems

REQUIREMENTS REVIEW
PROCESS
13
Plan review Distribute
documents
Prepare for
review
Hold review
meeting
Follow-up
actions
Revise
documents

REVIEW ACTIVITIES - 1
14
• Plan review
– The review team is selected and a time
and place for the review meeting is chosen
• Distribute documents
– The requirements document is distributed
to the review team members

15
• Prepare for review
– Individual reviewers read the requirements to
find conflicts, omissions,
inconsistencies, deviations from standards
and other problems
• Hold review meeting
– Individual comments and problems are
discussed and a set of actions to
address the problems is agreed

16
• Follow-up actions
– The chair of the review checks that
the agreed actions have been carried
out
• Revise document
– The requirements document is
revised to reflect the agreed actions.
At this stage, it may be accepted or it
may be re-reviewed

PROBLEM ACTIONS
17
• Requirements clarification
• Missing information
• Requirements conflict
• Unrealistic requirement

REQUIREMENTS CLARIFICATION
18
• The requirement may be badly expressed
or may have accidentally omitted
information which has been collected
during requirements elicitation

MISSING INFORMATION
19
• Some information is missing from the
requirements document. It is the
responsibility of the requirements
engineers who are revising the
document to discover this information
from system stakeholders

REQUIREMENTS CONFLICT
20
• There is a significant conflict between
requirements. The stakeholders
involved must negotiate to resolve the
conflict

UNREALISTIC REQUIREMENT
• The requirement does not appear to be implement-
able with the technology available or given other
constraints on the system.
• Stakeholders must be consulted to decide how to
make the requirement more realistic
21

PRE-REVIEW CHECKING - 1
22
• Reviews are expensive because they
involve a number of people spending
time reading and checking the
requirements document

PRE-REVIEW CHECKING - 2
23
• This expense can be reduced by using pre-
review checking where one person checks
the document and looks for straightforward
problems such as missing requirements,
lack of conformance to standards,
typographical errors, etc.
• Document may be returned for correction
or the list of problems distributed to other
reviewers

PRE-REVIEW CHECKING STAGES
24
Check
document
structure
Check
document
completeness
Check document
against
standards
Run
automatic
checkers
Requirements
document
Problems
report

REVIEW TEAM MEMBERSHIP
25
• Reviews should involve a number of
stakeholders drawn from different backgrounds
– People from different backgrounds bring different skills and
knowledge to the review
– Stakeholders feel involved in the RE process and develop an
understanding of the needs of other stakeholders
• Review team should always involve at least a domain
expert and an end-user

26
SUMMARY - 1
• Requirements validation should focus on checking the
final draft of the requirements document for conflicts,
omissions and deviations from standards
• Inputs to the validation process are the requirements
document, organizational standards and implicit
organizational knowledge. The outputs are a list of
requirements problems and agreed actions to address
these problems

27
SUMMARY - 2
• Reviews involve a group of people
making a detailed analysis of the
requirements
• Review costs can be reduced by
checking the requirements before the
review for deviations from organizational
standards. These may result from more
serious requirements problems

Lecture No-14.pptx Lecture No-14.pptx xx

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