Improving Systems and Software Quality through RequirementsDriven Development

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Improving Systems and Software Quality through
Requirements-Driven Development

• Andy Gurd

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The Systems Integration Jigsaw Puzzle

• Have you come to the end of a jigsaw puzzle only
  to find there are missing pieces or pieces from
  other puzzles that dont fit?
• In automotive vehicles, there are many pieces to
  fit together
• Mechanics
• Electrics
• Electronics
• Software
• Need to ensure sub-systems fit and work together

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Rain Sensing Wiper System Design Failure

• Windshield provided by local supplier
• Incompatible with the operation range of the
  sensor
• No captured requirement for proper system
  calibration
• Cars were sent to customers with non-functioning
  wiper system

• Initial diagnostics designated software as
  culprit for malfunction
• Mechanics couldnt test software behavior
• Components functioned normally when tested
  independently
• Failure mode resided at sub-system level

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Requirements-Driven Development

• Close gaps and link the product development
  lifecycle
• Reduce rework, delays and warranty costs improve
  customer satisfaction

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Requirements Engineering Best Practices
Best in class companies

• Engineer requirements
• From the beginning of the product and system
  lifecycle
• Through every phase of development
• Across all disciplines of mechanical, electronic
  and software
• Ensure traceability across all levels of
  requirements
• Mature from an isolated to a collaborative
  environment
• Invest the same focus and rigor on engineering
  requirements as in managing mechanical Bill of
  Materials
• Integrate Requirements Engineering closely with
  Change, Product and Portfolio Management, and
  Quality Assurance

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IBM and Telelogic Requirements Engineering
Solution

• Ensuring end-to-end traceability
• From ideas, requirements and feature definitions,
  product/system specifications and models
• To mechanical, electric/electronic and embedded
  software implementation, test and maintenance

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Requirements management and traceability

• Comprehensive support for recording, structuring,
  managing, and analyzing requirements and their
  traceability
• Requirements are persistent at all levels of
  decomposition

• Can manage requirements across multiple
  engineering disciplines - Software, Electronic
  Mechanical
• Scalable for large projects with many users

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Collaborative requirements engineering

• Requirements analysts / Systems Engineers author
  requirements using rich desktop client

• Manufacturing/ QA / Suppliers review and comment
  on requirements through web browser

RequirementsDatabase
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A picture paints a thousand words?
2 Functional Requirements 2.1 Power car 2.1.1
Move car 2.1.1.1 Move forwards The car shall be
able to move forwards at all speeds from 0 to 200
kilometers per hour on standard flat roads with
winds of 0 kilometers per hour, with 180
BHP. 2.1.1.2 Move backwards The car shall be able
to move backwards to a maximum speed of 20
Kilometers per hour on standard flat roads with
winds of 0 kilometers per hour, with 180
BHP. 2.1.2 Accelerate car The car shall be able
to accelerate from 0 to 100 Kilometers per hour
in 10 seconds on standard flat roads with winds
of 0 kilometers per hour. The car shall be able
to accelerate from 100 to 150 kilometers per hour
at a rate of 5 kilometers per second on standard
flat roads with winds of 0 kilometers per
hour. The car shall be able to accelerate from
150 to 200 kilometers per hour at a rate of 3
kilometers per second on standard flat roads with
winds of 0 kilometers per hour. 2.2 Control
car 2.2.1 Switch on car The car shall be able to
discriminate which authorized people shall be
able to switch on and operate the car. 2.2.2
Control speed The car shall have a foot mechanism
to control the speed of the car. The speed
control shall be infinitely variable from zero to
maximum speed. The speed of the car shall be
controllable by automatic means. 2.2.3 Brake
car The car shall be able to stop from 10
kilometers per hour to 0 kph in 2 seconds. The
car shall be able to stop from 30 kilometers per
hour to 0 kph in 6 seconds. The car shall be able
to stop from 100 kilometers per hour to 0 kph in
30 seconds. The car shall be able to stop from
200 kilometers per hour to 0 kph in 45 seconds.
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A picture paints a thousand words?
2 Functional Requirements 2.1 Power car 2.1.1
Move car 2.1.1.1 Move forwards The car shall be
able to move forwards at all speeds from 0 to 200
kilometers per hour on standard flat roads with
winds of 0 kilometers per hour, with 180
BHP. 2.1.1.2 Move backwards The car shall be able
to move backwards to a maximum speed of 20
Kilometers per hour on standard flat roads with
winds of 0 kilometers per hour, with 180
BHP. 2.1.2 Accelerate car The car shall be able
to accelerate from 0 to 100 Kilometers per hour
in 10 seconds on standard flat roads with winds
of 0 kilometers per hour. The car shall be able
to accelerate from 100 to 150 kilometers per hour
at a rate of 5 kilometers per second on standard
flat roads with winds of 0 kilometers per
hour. The car shall be able to accelerate from
150 to 200 kilometers per hour at a rate of 3
kilometers per second on standard flat roads with
winds of 0 kilometers per hour. 2.2 Control
car 2.2.1 Switch on car The car shall be able to
discriminate which authorized people shall be
able to switch on and operate the car. 2.2.2
Control speed The car shall have a foot mechanism
to control the speed of the car. The speed
control shall be infinitely variable from zero to
maximum speed. The speed of the car shall be
controllable by automatic means. 2.2.3 Brake
car The car shall be able to stop from 10
kilometers per hour to 0 kph in 2 seconds. The
car shall be able to stop from 30 kilometers per
hour to 0 kph in 6 seconds. The car shall be able
to stop from 100 kilometers per hour to 0 kph in
30 seconds. The car shall be able to stop from
200 kilometers per hour to 0 kph in 45 seconds.
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or hides a thousand requirements?
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or hides a thousand requirements?
The swing shall be able to support a weight of
100lbs The swing should be large enough to carry
2 small children The swing shall never be lower
than 0.5 meters from the ground The swing shall
be not be able to swing through more than 180
degrees The swing rope shall have an elasticity
of. The swing shall comply with the following
safety standards.. The swing shall The swing
shall The swing shall The swing shall
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The systems engineering club sandwich
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Simulate not build and break

• You dont build a complete vehicle before testing
  it meets aerodynamic requirements
• Why wait until youve written software before
  verifying your design is going to meet the
  requirements?
• Finding and fixing problems in the requirements
  and design phases is orders of magnitude cheaper

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Model simulation for requirements validation
Expected Requirement Scenario

• Use requirement scenarios to validate the design
• Simulate to verify that model is correct
• Avoid errors
• Reduce costly rework
• Increase quality
• Virtual prototype / Panel graphics support
• Ideal communications aid for design reviews and
  to share information.

Simulation Results
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Linking requirements to design models

• Traceability helps prove conformance and
  compliance
• Easily check for
• Requirements not satisfied by the design
• Design elements with no linked requirements
  gold plating
• Fast and complete impact analysis
• Assess full impact of changes BEFORE they are
  made
• Ensure approved changes are fully implemented

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End to end traceability management and reporting

• Focus on an individual requirement and its
  traceability hierarchy
• Produce graphical traceability reports for
  auditors and management
• See only the project information relevant for
  your role

• Decompose requirements system reqts, mechanical
  /electrical/ electronic/ software subsystem
  reqts, etc.
• Create traceability by drag-and-drop linking
• View dynamic end-to-end traceability reports

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Impact analysis
If documents are linked
shows up as a warning flag to this user here.
a change by this user here
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Summary

• Analyze impact of requirements changes
• Maintain traceability for conformance and
  compliance
• Link requirements and design
• Simulate not build and break
• Use models and text
• Collaborate across disciplines
• Close gaps and link the product development
  lifecycle
• Reduce rework, delays and warranty costs improve
  customer satisfaction

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For more information

• Visit us at Stand 12
• Visit our website www.telelogic.com