Ackerman-p99.ppt

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Software Inspections
and Walkthroughs
Author: A. Frank Ackerman
Presented by Cynthia Johnson
EEL6883

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Software Inspections
 “Software Inspections are a disciplined
engineering practice for detecting and
correcting defects in software artifacts,
and preventing their leakage into field
operations.” Don O'Neill, Don O' Neill
Consulting for SEI

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Software Walkthroughs
 a form of software peer review "in which a
designer or programmer leads members of the
development team and other interested parties
through a software product, and the
participants ask questions and make
comments about possible errors, violation of
development standards, and other problems"
(IEEE Std. 1028-1997, IEEE Standard for
Software Reviews, clause 38.

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What’s the difference?
 An inspection is a more formal process
than a walkthrough used to collect
metrics or statistics about the software
process
 Walkthrough is a more informal version of
an inspection

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Why inspect software?
 Routine production of reliable software within
budget and on schedule continues to elude
most development organizations.
 While efforts are ongoing to make development
an industrial process, much of the work is still
done by “intellectual artisans”
 Artisan’s work is inherently difficult to bond and
can not be specified precisely.
 Inspections are a method to reduce variability
and tighten process control.

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History of Inspections
 M.E. Fagan of IBM first defined
inspections in 1976.
 E. Yourdon was among the first to publish
a book on inspections in 1978.
 IEEE standard covering inspections first
appeared in 1988.

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What do inspections
cover?
 Inspections and walkthroughs are
primarily intended to discover defects in
software artifacts.
 This is a static analysis technique of
software testing.
 In addition, inspections address three
major tasks of process management:
planning, measurement, control.

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Inspection metrics
 Inspections are used to collect quantitative
quality data at defined points in the
development process.
 This can be used to give feedback to the
developers, feed-forward to future
development, and feed-into future steps of
process.
 Can also provide data on effectiveness of
inspection techniques.

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What can be inspected?
 Inspections can be held a various points
in development process.
 Fagan recommended inspections on:
 Detailed design
 Cleanly compiled code
 Completion of unit test

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Who is involved?
 At a minimum a formal inspection
includes:
 Designated moderator
 Author of the work
 At least one peer inspector
 Walkthroughs generally do not include
designated moderator and are often led
by the author of the software.

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Steps of inspection
 Planning
 Overview
 Preparation
 Meeting
 Rework
 Follow-up

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Planning
 Planning begins when entry criteria for
inspection type is met.
 Moderator is selected – usually a peer or
technical leader
 Selection may be made by developer, but this
is generally not an ideal situation
 Management is encouraged not to look at
individual inspection results
 Moderator verifies that product meets entry
criteria and schedules future steps.

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Overview
 Presentation to inspectors with any
background information needed to
properly review software product.
 Purpose is educational only
 Data collected is author preparation time
and time spent on presentation.

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Preparation
 Individual activity
 Author collects all material required for
inspection
 Inspectors study the material and
complete inspection log.
 Defects are noted at this step, but not
collected

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Meeting
 Meeting is conducted by moderator
 Agenda includes:
 Introduction
 Establishing readiness
 Examining material and recording defects
 Review defects
 Determine disposition
 Debrief
 Defect data is collected this time

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Common meeting
problems
 Interpersonal tensions are most likely to arise
at this point
 Experienced moderators can detect and
defuse this tension
 The more inspections that occur, the less likely
interpersonal tensions are to interfere
 Effort should be made by all participants to
keep emphasis on producing quality product,
not making fault finding personal

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Rework
 Performed by the author in response to
defect disposition determined at meeting

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Follow-up
 Moderator verifies that corrections are
made
 Moderator completes inspection
management report and defect summary
report

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Inspection Roles
 Author – developer of work product
 Moderator – an inspector responsible for
organizing and reporting on inspection
 Reader – an inspector who guies the
examination of the product
 Recorder – an inspector who enters all the
defects found on the defect list
 Inspector – Member of inspection team. Often
chosen to represent specific role- designer,
tester, technical writer, SQA, etc

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Inspection as Process
Control
 When employed at various points
through out the process, the completion
of an inspection can trigger entry into a
new development phase.
 Generally, Software Development Plan
spells out entry and exit criteria and
required participants in each type of
inspection.

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Aspects of inspections
 Initial introduction of inspection into an
organization can cause anxiety and
tension among developers
 When it becomes clear that management
supports inspection as a quality
improvement technique and not a witch
hunt, the effectiveness of the inspection
increases.

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Inspection Data
 The collection and analysis of data is
what sets inspections apart from other
peer review techniques such as
walkthroughs.
 This data can be used in a variety of
ways by a variety of personnel.

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Data customers
 First-line managers – amount of rework
generates schedule information
 Next phase developers or verifiers get
“intelligence” report on status of software
 Quality assurance personnel use data on
amount of material inspected, amount of
inspection material, speed of examination
to examine inspection effectiveness

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More data usage
 Quality assurance is responsible for
recommending inspection and
preparation rates – actual review data
makes these more realistic
 Defect rates and types discovered at
different points can point to most effective
place to review. For example, design
inspections may prove more cost
effective than code.

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Alternatives
 There is a “cost of quality” associated with
walkthroughs and inspections. In software,
person-hours are the highest measurable
expense
 Many organizations find that the cost of
inspection does not generate a return on
investment
 Some inspect a percentage of code
 Others inspect only critical portions

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Conclusions
 Inspections have been proven an efficient
and effective method for improving
software quality
 In conjunction with testing, audits and
formal verification a successful, quality
product can be produced

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My opinion
 When done correctly, walkthroughs and
inspections are valuable defect finding tools.
 When not supported by management or bought
into by development personnel, they become
“busy work” for developers.
 It is important for developers to not take
criticism personally.
 It is equally important for inspectors to look for
defects and not criticize because developer
didn’t code exactly the way they would

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References
 http://www.sei.cmu.edu/str/descriptions/in
spections_body.html
 IEEE Std. 1028-1997, IEEE Standard for
Software Reviews

Ackerman-p99.ppt

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