Building a Comprehensive
Software Product Line Cost Model
Andy Nolan BSc Hons, CEng, FBCS, CITP
Chief of Software improvement – The Software Centre of Excellence
©2010 Rolls-Royce plc
The information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose
other than that for which it is supplied without the express written consent of Rolls-Royce plc.
This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given
concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of
its subsidiary or associated companies.
Engine Control Systems
2
 The control system is fundamental to the certification of the engine
and Airframe. The Control system software is classed as safety critical
Electronic Engine Controller
 Certification evidence cannot be
easily generated centrally but
must be gathered on each project
instance, during system
integration and integration with
the hardware
 Gathering this evidence, which
can be over 50% of the Control
Systems project’s total cost, has
to be incurred on each configured
project instance.
 Projects are typically low volume
and are individually configured
for their application.
Rolls-Royce data
3
Source Lines of Code
Size (Functionality)
The demand for software functionality is growing
Functional Growth between 4%
and 10%/year AND a growing
legacy of obsolete platform
requiring refresh
0%
1990
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1995
2000
2005
2010
2015
Process Improvement will soon end
4
EEC Control System Software
Cost per Function Relative to"Baseline"
Cost Per Function Relative to "baseline"
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
Evolution has halved the costs of
our projects. Process refinement
may be reaching its natural limits.
The next improvements will be in
product design
0%
1994
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1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
5
Inputs
SIMPLE
CO-PL-MO
level cash flow and benefits
 guide the Project – when to adopt, when to
clone and own, when to say “No”
 guide the Architects – select the right
assets & the right variation mechanisms
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Asset Data
Rolls-Royce data
Rolls-Royce
Process Data
Rolls-Royce
Past Project Data
Experience
COCOMO
 guide the Business - to estimate business
COCOMO – The Development Environment
Relative Productivity
PREC –
Preceden
ce
(Novelty)
SITE –
organisati
on sites
Relative Productivity
TEAM –
team
cohesion
PMAT
Process
Maturity
Experienc
e (APEX,
PLEX &
LTEX
RESL Risk
and
Architecture
result ion
TOOL
Capability
REVL
Requirements
Volatility
Baseline Project 1 Project 2 Project 3 Project 4 Project 5 Project 6 Project 7 Project 8 Project 9Project 10
Project
You do not necessarily need products in your
Product Line to add value to the business
Rolls-Royce data
6
7
Overview of the Model
Traditional
PL
Common
Library
Step 4 Project
Reuse Plan
Step 1
Determine
Asset Size
Step 2
Determine
Asset Value
Factors for
asset “value”
rather than
size
Step 3 Asset
to Project
Mapping
P Process
Model
Step 5 PrL
Asset
Development
Step 10 Cost
Benefit
Step 6 PL
Deployment
Plan
Step 7 PL
Project Costs
Disruption to the
“environment”
(CO-CO-MO)
Number of
deployments
Factors for safety critical
processes and
The additional
verification performed by
Product Line
each project
development costs
(CO-PL-MO)
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Step 8 PL
Organisation
Costs
The organisational
overheads to
govern PL and
train the business
Only relative
benefits used
Step 9 PL
Environment
8
Business Model Outputs
PL Benefit Cross Over Point
Cumulative $$€
Traditional Cumulative$M
Product Line $M
PL Develop P1
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P2
P3
P4
P5
P6
P7
P8
P9
P10
9
Asset Management
Net Benefit Including development and
deployment SLOC
69%
#DIV/0! #DIV/0! 69%
63%
54%
54%
54%
#DIV/0!
0%
0%
57%
16%
#DIV/0! #DIV/0! #DIV/0!
0%
0%
0%
57%
57%
57%
57%
57%
57%
57%
57%
-42%
57%
57%
70%
57%
53%
53%
68%
53%
57%
57%
57%
57%
26%
25%
42%
39%
In some cases, it
may be more
economical to clone
and own an asset
rather than use a
Product Line option
Rolls-Royce data
69%
54%
57%
-175%
-42%
57%
-42%
57%
53%
-42%
35%
Project n
Project 8
Project 7
Project 6
Project 5
Project 4
Project 3
Project 2
Function (Step
1)
Function 1
Function 2
Function 3
Function 4
Function 5
Function 6
Function 7
Function 8
Function 9
Function 10
Project 1
% Saved (green) or lost (Red)
PL
Traditional Develop PL Deploy
Hours
Hours
Hours
% Saved
69%
69%
69%
69%
1445
288
455
49%
54%
54%
63%
-50%
9754
1464
4678
37%
57%
57%
65% #DIV/0!
13434
3925
7671
14%
#DIV/0! #DIV/0! 16% -175%
68298
2993
87847
-33%
-42%
57%
57%
-42%
17055
6011
13454
-14%
57%
57%
57%
44%
12233
3453
5464
27%
57%
57%
65%
-42%
21079
8582
11034
7%
57%
65%
57%
-42%
9697
2432
4209
32%
53%
62%
53%
-55%
149154
17585
72791
39%
57%
57%
-42% -42%
96111
31616
54722
10%
44%
46%
41%
19%
2528110
233896 1619160
In some cases, there is no
overall benefit from
developing a Product
Line Asset
In conclusion
 If you do not have a cost model of your
Product Line – then make one!
Despite some people’s beliefs, they are
relatively easy to build
 The best solution is often counter intuitive don’t rely on subjectivity (alone)
 Data makes decision making and persuasion
very easy
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10
Back u slides
©2010 Rolls-Royce plc
The information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose
other than that for which it is supplied without the express written consent of Rolls-Royce plc.
This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given
concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of
its subsidiary or associated companies.
Some observations from the model
 You must select assets based on their value
rather than size.
 Not every assets will benefit from being made
into a Product Line
 Doing nothing is still expensive in a safety critical
world (verification of the asset in situ).
 You do not need products in your Product Line in
order to add value!
 Introducing a Product Line strategy "disturbs" the
organisation – factor for it
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12
A model is at the heart of a business
13
Do you know if you
can meet your
business goals?
Business Goals
Set Project
Goals & Targets
Do you know
what you are
capable of
achieving?
Understand
Capability
Do you know
what is
important
and what to
monitor?
Estimate
& Plan
Project
Improve
capability
Monitor
& Control Project
Benchmark
Capability
Do you know what to improve?
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14
Cost (Effort)
Our philosophy
Rolls-Royce data
New
New Product
Development
The costs to
start with a
blank sheet of
paper
From traditional
reuse (clone and
own) we would
have expected
some savings The business case
is based on the
delta between the
Product Line and
Traditional
what the project
would have cost
What the
project would
have cost had
we not used a
Product Line
(some clone
and own)
Product Line
Cost of the
project based
on Product
Line Strategy
15
Estimated Resource
Estimated Resource Profiles (FTE)
Resource (Engineers)
PL Deployment
PL Asset Development & Overheads
Traditional Project
Year 1
Year 2
Year 3
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Year 4
Year 5
Year 6
Year 7
Year 8
Year 9
Year 10
Year 11
Year 12
Year 13
Year 14
Year 15
Year 16
Year 17
Year 18