Lean Thinking Inside and Outside a Software Engineering Company (Dave Jackson)

Lean Thinking Inside and Outside a Software Engineering Company
AdaCore Lean/Agile Event
Paris
March 2009
Dave Jackson
Technical Delivery Manager
Praxis High Integrity Systems Limited

Desired Value
To inform you of the background to Praxis’ work with Lean principles
To give examples of how we’ve adopted Lean
In our internal business processes
In our delivery to clients
To identify some implications and opportunities

Praxis – Basic Facts
Established in 1983
First software company to BS5750 (now ISO 9001)
Turnover $24M
Permanent staff c. 150
Locations
UK: Bath, London, Loughborough
International Expansion: Paris, …
Markets
Strategic: Defence, Aerospace, ATM, Rail, Nuclear
Tactical: Automotive, Medical, Finance
Part of the Altran Group
Since 1997
Turnover $2.5Bn
Staff of 17,000
Global: Europe, USA, Asia, South America

Desired Value

Praxis Approach to Software – Correctness by Construction
C-by-C has the same guiding principles, whatever the lifecycle phase:
Combine safety, security and operational constraints in every step
Capture information completely and precisely
Make small, well-defined, analysable steps
Document once, in the right place
Verify correctness before moving to next step
Justify approach before moving to next step
Use the best tool for the job at each step
Use intelligence, not just “box-ticking mentality”

Core Process & Example Techniques
Requirements eg use of REVEAL (inspired by work of Professor Michael Jackson)
High level design eg use of UML
Specifications (precise and complete black box descriptions of behaviour) eg use of CSP, Z, etc.
Detailed design eg INFORMED (in-house Praxis proprietary method)
Module Spec & Code eg SPARK

SPARK™
A language, toolset and design approach for the development of ultra-reliable software.
A design and implementation technology for high integrity software
Enables proof of correctness, and absence of run-time errors (eg buffer overflows)
Enables deep static analysis, including separation of safe/secure and unsafe/insecure state
Example uses
All flight critical software on Eurofighter
Tornado, Harrier, Hawk, Hercules, Nimrod, A380
Mastercard SMART card, ALSTOM ERTMS

Example Project 1 – NATS iFACTS
interim Future Area Control Tools Support (iFACTS)
Development of new air traffic control tools to increase capacity in UK airspace
Trajectory prediction, Conflict detection, Flight path monitoring
Specified and implemented by Praxis, as an addition to existing NERC system
Joint Praxis / NATS team
Part of wider NATS IPT
Includes training NATS staff
SW01 (US’s ESARR 6) safety evidence provided using Praxis’ C-by-C methods

Example Project 2 – SHOLIS
Ship Helicopter Landing System
First ever project delivered to Interim DEF STAN 00-55, SIL4
Specified in Z
Written in SPARK
Formal proof of both Z and SPARK very effective
Demonstrated that proof is more cost effective than testing
Demonstrated that system testing more cost effective than unit testing
Developed for a fixed price
7 LOC per day
0.22 defects per KLOC

Desired Value

Principles of Lean Thinking
Specify value : Value is defined by customer in terms of specific products & services
Identify the value stream : Map out all end-to-end linked actions, processes, and functions necessary for transforming inputs to outputs to identify and eliminate waste
Make value flow continuously: Having eliminated waste, make remaining value-creating steps “flow”
Let customers pull value: Customer’s “pull” cascades all the way back to the lowest level supplier, enabling just-in-time production
Pursue perfection : Pursue continuous process of improvement striving for perfection
After Murman
FOCUS

Principle 1 – Value
Products and services defined by the customer
Example
Independent V&V project
Deliverables: Plan, Process, Specifications
Client need: Bug reports, Regression tests
Tools
Stakeholder analysis
Context modelling
Workshops
Does the value of a program lie in the output, or the error messages? http://farm3.static.flickr.com/2218/2180467051_0202df7e4f.jpg

Principle 2 – Waste
Anything which does not contribute to value
Many forms of waste
Delay
Rework
Nugatory work
Overstretch
Tools
Product breakdown structure
Right-to-left planning
Correctness by Construction
Example: Re-planning a major railway upgrade programme to identify essential dependencies identified a 30% saving

Principle 3 – Flow
Processes linked by sequential dependencies progress at the rate of the slowest
Example: Waterfall software lifecycle (Requirements, Architecture, HLD, LLD, Code, Test)
Tools: R-to-L planning, Spiral / Parallel lifecycles, Takt time, Theory of Constraints
Kanban - a token carrying the information necessary to produce a desired item

Desired Value

Lean Inside the Company
Praxis sees lean principles as a key part of its own business processes
Process improvement approach suggested by the principles:
Identify value
Seek & eliminate waste
Maximise forward flow of value
Pull through self-explanatory tokens
Examples:
Recruitment
Project initiation
Also used in staff performance review, …

Lean Recruitment
Problem environment
Recruitment was taking too long
Senior staff were spending lots of time reviewing CVs and interviewing
Analysis
Value: a suitable employee starts work at the right time on a package which motivates them
Waste: inappropriate interviews, offers declined, renegotiation of package, delays

Lean Recruitment
Vacancy token drives advertising and selection
Interview dates specified in advertising
Management approval of package
Candidate token drives recruitment of an individual
Carries all personal details
Provides guidance on each action (review, interview, offer)
Outcome
Able to increase permanent and contract staff by around 50% in 12 months
CV review effort down by a significant factor

Lean Project Start-up
Problem environment
Opportunities developed by business managers and bid teams
Focussed on winning work
Projects delivered by operational organisation
Focussed on successful delivery
Project initiation perceived as taking unnecessary time / effort

Lean Project Start-up
Action
Bid token tracks opportunity from prospect to project
Includes bid strategy, initial plans
Automatically identifies necessary approvals (inc specialist review)
Make plan and assumptions available to project team
Outcome
Reduced change
Many project plans now subsumed by simple project brief

Desired Value

Lean Outside
Above examples are internal
As consultants we offer our successful experiences to our clients
Skills delivered through both
Adoption on fee-earning projects
Skills transfer in consultancy engagements

Lean Modification Process
Problem Environment
Substantial software project enters new delivery phase on completion of a milestone
Outstanding modification backlog grows
Analysis
Most changes are made quickly
Small selection subject to very long negotiation

Lean Modification Process
Improve quality of modifications on entry into change process
Review checklist
Early rejection of inappropriate or inadequately characterised change
Action and result
Significant reduction in modification backlog
Backlog Time Change

White Box Safety
Context
Safety-critical systems subject to rigorous assessment
Prescriptive standards for documentation and evidence
Large quantities of evidence
Changes in environment may invalidate parts of argument / evidence
Safety standards are traditionally prescriptive,
Not targeted at product (only process),
Wasteful

White Box Safety
Approach
Value: Acceptable argument of fitness for purpose
Evidence not directly required for this is waste
Outcome
Smaller cheaper and more compelling safety cases & products
Change only requires rework where it matters for the safety of the product
Context-dependent safety arguments captured, eg, in Goal Structured Notation (GSN)
Modern and emerging safety standards strongly supportive of this approach

Desired Value

Implications
High integrity systems traditionally inflexible
Legacy standards
Heavyweight processes
Lean has useful lessons
Concentrate process on where it adds value
Reduce waste: lower cost, improved timescales, profit.
And it helps your company run smoothly too!

Opportunities
There is a Lean route to good product
And it can be cheaper than traditional means
Focus on
Defect elimination (value)
Early defect removal (waste)
Minimise dependencies between outputs
Capture evidence as it’s needed, if it’s needed

Praxis High Integrity Systems Limited
20 Manvers Street
Bath BA1 1PX
United Kingdom
Telephone: +44 (0) 1225 466991
Facsimile: +44 (0) 1225 469006
Website: www.praxis-his.com
Email: David.Jackson@praxis-his.com
Mobile: +44 (0) 7920 151391

Lean Thinking Inside and Outside a Software Engineering Company (Dave Jackson)

by AdaCore on Apr 18, 2009

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Lean Thinking Inside and Outside a Software Engineering Company (Dave Jackson) — Presentation Transcript