Sustainability - The Software Perspective

Patricia Lago
Vrije Universiteit Amsterdam
Presented at: University of L’Aquila, Dec. 2021
Sustainability – The
Software Perspective

i. SOFTWARE CAN HELP, OR HINDER,
SUSTAINABILITY
ii. SOFTWARE ARCHITECTURE MAY PROVIDE THE
NEEDED “BIG PICTURE”
iii. DECISION MAKING MUST BE INFORMED
Takaways

https://vu.nl/en/about-vu/more-about/discover-our-campus

The S2 group @ VU Amsterdam
I/O Magazine, Issue 3, Dec. 2020
s2group.cs.vu.nl

The S2 group @ VU Amsterdam
• Software Architecture Design for Digital Sustainability
• Architectural Technical Debt
• Software Energy Footprint
• Robotics Software
• Software Engineering and Ethics
• Software Adaptation
s2group.cs.vu.nl

Highlights of my journey in Software and Sustainability
2015
ICSE SEIS
MASTER'S TRACK IN
COMPUTER SCIENCE
SOFTWARE
ENGINEERING
AND GREEN IT
WWW.VU.NL/COMPUTERSCIENCE
2012 2020 2023
Sustainability chair
2022
2014
Inaugural
lecture on
“software and
sustainability”
2016
SC chair
Official Launch
2021
se4gd.eu

WHEN WE THINK ABOUT
SOFTWARE AND SUSTAINABILITY
WHAT IS THE FIRST THING THAT COMES TO MIND?

“LIKE PERFORMANCE, RELIABILITY, SECURITY,
SUSTAINABILITY DOES NOT JUST HAPPEN
UNLESS WE PLAN FOR IT.”
Patricia Lago @ 2016 Inaugural speech

Part 1 - What is software sustainability? Why architecture?

Perspectives on Sustainability
Dimensions of focus Order of effects
UN Sustainable
Development Goals
DIRECT IMPACT
(technology)
ENABLING IMPACT
(supported processes)
SYSTEMIC IMPACT
(change in behavior)
https://sdgessentials.org/why-
the-world-needs-the-sdgs.html
REBOUND EFFECTS
(negate intended impact)
Technical
Environmental
Economic
Social

The role of software in sustainability: two perspectives
Direct impact
(sustainable software)
Inward looking
SOFTWARE-INTENSIVE
SYSTEM
ENERGY EFFICIENCY MAINTAINABILITY
STABILITY
Indirect impact
(software for sustainability)
Outward looking
SOFTWARE-INTENSIVE
SYSTEM
TRUSTABILITY
USABILITY
DIGITAL INCLUSIVENESS

The role of software in sustainability: dimensions of focus
Inward looking
SOFTWARE-INTENSIVE
SYSTEM
Outward looking
SOFTWARE-INTENSIVE
SYSTEM
Technical Environmental Economic
Social
Direct impact
(sustainable software)
Indirect impact
(software for sustainability)

The role of software in sustainability: order of impacts
S
O
F
T
W
A
R
E
I
M
M
E
D
I
A
T
E
I
M
P
A
C
T
E
N
A
B
L
I
N
G
I
M
P
A
C
T
S
Y
S
T
E
M
I
C
I
M
P
A
C
T
Impacts can be seen in different
timescales
• First order/Direct/Immediate
• Second order/Indirect/Enabling
• Third order/Structural/Systemic

The role of software in sustainability: rebound effects
• [Def] “... characterize the negative side effects of efficiency policies and
strategies that ended up taking back the environmental gains they had
permitted”.
• Intrinsically cross-dimensional
• Negative (but may be positive)
• Unpredictable àcountermeasures
What is the role of government in the digital age? (n.d.). Retrieved September 26, 2020, from
https://www.weforum.org/agenda/2017/02/role-of-government-digital-age-data/

Reflection point
WE CAN TALK ABOUT “SUSTAINABILITY” IF AND ONLY IF WE ADDRESS
BOTH THE DIMENSION(S) OF FOCUS
AND A TIMESCALE

Why software digital architecture?
DIGITAL
ARCHITECTURE
SYSTEMIC IMPACT
ENTERPRISE
organization à communities
CONTEXT
partnerships à multi-sector
BUSINESS
economic à ecologic
Digital transformation is
blurring the lines between
digital and physical

Part 2 - The SAF Toolkit and Decision Maps
SUSTAINABILITY
ASSESSMENT
FRAMEWORK

Condori-Fernandez, N., Lago, P., Luaces, M. R., & Places, Á. S. (2020). An action research for improving the sustainability assessment framework
instruments. Sustainability (Switzerland), 12(4), 1-25. https://doi.org/10.3390/su12041682
A Checklist to help define the
elements of a DM
The Decision Map (DM) to help explore
the design space and make decisions
The SQ dependency matrix to
help identify the dependencies
among DM elements
The Decision Graph to help
assign the right impact
timescale to DM elements
The Sustainability-Quality (SQ) Model to
define concerns and measures
The SAF Toolkit

Design Decision Maps’ Notation
An example with Decision maps: conferences
(*) for the sake of the presentation some concerns are over-simplified
1 M. Funke and P. Lago (2021), “Let’s start reducing the Carbon Footprint of Academic Conferences”, Technical Report VU Amsterdam. Under Submission.
2 Lago, P. (2019). Architecture design decision maps for software sustainability. In IEEE/ACM 41st International Conference on Software Engineering: Software
Engineering in Society, https://tinyurl.com/DesDmaps
SUSTAINABILITY
IMPACTS
FEATURE
CONCERN
EFFECT

Design Decision Maps’ Notation
An example with Decision maps: conferences
(*) for the sake of the presentation some concerns/effects are over-simplified
2 Lago, P. (2019). Architecture design decision maps for software sustainability. In IEEE/ACM 41st International Conference on Software Engineering: Software
Engineering in Society, https://tinyurl.com/DesDmaps

Example: KPMG Qubus Platform: visualization of
planned vs. actual effects
Verdecchia et al. (2017). Estimating Energy Impact of Software Releases and Deployment Strategies: The KPMG Case Study.
https://tinyurl.com/y63y2qfr
DECISION MAPS CAN BE
REFINED WITH THE ACTUAL
EFFECTS AND EFFECT MEASURES
(counter-intuitive) The
version with a ‘distributed’
deployment strategy led to a
-10% power consumption
wrt. the centralized one.
Performance (in terms of
execution time) largely
depends on the usage
scenarios’ requirements for
data load.

Example: smart work: reasoning
Amsterdam
Smart City
DECISION MAPS HELP
EXPLORE THE DESIGN SPACE
These effects could lead to
rebound impacts (e.g.
reinvesting savings
elsewhere, like a house
further away - hence leading
to longer travels when
needed)
Remote access leads to introducing
additional tech services (with increased
energy footprint) and may damage
collaboration (possibly with further negative
effects on work efficiency)
Niggebrugge, T., Vos, S., & Lago, P. (2018). The Sustainability of Mobility as a
Service Solutions Evaluated through the Software Sustainability Assessment
Method. VU Technical Report.

Example: WhatsApp Neighborhood Prevention: informed
decision making
• A sustainability goal à one or more
questions each regarding a
sustainability-quality (SQ) concern
GOAL à How to make neighborhoods safer?
- By engaging the citizen in informing the
police of criminal situations like suspect of
robberies
WhatsApp
Neighborhood
Prevention

decision making
WhatsApp
Neighborhood
Prevention
1: the original plan
2: the measured impact
sustainability goal à
max safety, min criminality

decision making
WhatsApp
Neighborhood
Prevention
1: the original plan
2: the measured impact 3: the corrected plan
sustainability goal à
max safety, min criminality
max social cohesion + police guidance

How can I build true impact?
• A sustainability goal à one or more
questions each regarding a
sustainability-quality (SQ) concern
• The measures of the SQ concerns
express the effects
• The variation (or trend) over time
expresses the impact towards
the sustainability goal

Decisions based on a (quantifiable) informed strategy
Renewable Energy Provisioning: Sharing IoT assets
[Vandebron]
Sustainability Goal = {
• Balance Energy prosumption
• Maximize Trust
• Enable positive behavioral
change }
Lago, P. et al (2020). Designing for Sustainability: Lessons
Learned from Four Industrial Projects. EnviroInfo.
https://tinyurl.com/fourcases

Reflection point
1Procaccianti, G., Lago, P., Vetrò, A., Méndez Fernández, D., & Wieringa, R. (2015). The Green Lab: Experimentation in Software Energy Efficiency. In IEEE/ACM ICSE.
https://doi.org/10.1109/ICSE.2015.297
HOLISTIC VIEW TRENDS OVER PRECISION
We understand real impact only
over time and space
Precise measures depend on too many
specific variables; trends help identifying
patterns hence energy (or sustainability)
hotspots1

Remember the example: a sustainability model for scientific
conferences
po i i e
po i i e
po i i e
ne al
ne al
ne al
ne al
nega i e
po i i e
nega i e
nega i e
nega i e
po i i e
po i i e
po i i e
ne al
ne al
ne al
ne al
nega i e
po i i e
nega i e
nega i e
nega i e
po i i e
po i i e
po i i e
ne al
ne al
ne al
ne al
nega i e
po i i e
nega i e
nega i e
nega i e
ON-SITE VIRTUAL HYBRID
Sustainability Goal = {
• Minimize carbon footprint
• Max knowledge transfer
• Balance ICT investments }

Reflection point
1 R. Alidoosti, P. Lago, M. Razavian, and A. Tang, “Ethics in software engineering: a systematic literature review,” 2021, under submission.
2 Moyer, A. :. K., Mingay, S., & Watt, S. (2021). Leading Sustainability Ambition, Goals and Technology in the 2020s. Gartner.
ON STAKEHOLDERS ON FLEXIBILITY
3-level stakeholder analysis: indirect ones = critical yet forgotten
The BIG assumption, and
challenge, is flexibility

Lago, P. © 2016-2018 SoSA: A Software Sustainability
Assessment Method. Available at: https://goo.gl/HuY6tf
Condori-Fernandez, N., & Lago, P. (2018). Characterizing
the contribution of quality requirements to software
sustainability, Journal of Systems and Software, 137, 289-305.
Why digital architecture? choosing the dimensions of focus
(Software) sustainability is cross-dimensional: gather awareness
AI-assisted desk workers
25

Why digital architecture? choosing the dimensions of focus
(Software) sustainability is cross-dimensional: gather awareness

(Software) sustainability is measurable only over time:
gather awareness
Why digital architecture? making decisions that last

(Software) sustainability is measurable only over time:
gather awareness
Why digital architecture? making decisions that last
Condori-Fernandez, N., & Lago, P. (2018). Characterizing the
contribution of quality requirements to software sustainability, Journal
of Systems and Software, 137, 289-305.

Reflection point
ARCHITECTURE AND TIME
TECHNICAL- VS. SUSTAINABILITY-DRIVEN
ARCHITECTURE DESIGN DECISIONS
Unknown by ISO/IEEE/IEC 42010
(among others)
Decision Maps provide “a” type of
(architecture) view.
The link with technical views needs work.

Want to know more? … some recent work
0740- 745 9/19©2019IEEE NOVEMBER/DECEMBER 2019 | IEEE SOFTWARE 79
REQUIREMENTS
Editor: Philippe Kruchten
University of British Columbia
pbk@ece.ubc.ca
SOUNDING BOARD
ACCORDING TO RECENT estimates,
computing and communications could
account for 20% of energy usage glob-
ally by 2025.1 This trend shows no
sign of slowing. The annual growth in
power consumption of Internet-con-
nected devices is 20%. Data centers
alone are now accounting for more
than 3% of global emissions. Even if
you are not worried about this trend
on the mega scale, you are likely con-
cerned with the power consumption
of the devices in your pocket, on your
wrist, and in your ears.
Software, hardware, and network
attributes all contribute to power
usage, but little attention has been
given to this topic by the informa-
tion and communications technol-
ogy (ICT) community. For example,
as software engineers, we were never
taught to consider, much less man-
age, the energy consumption of the
software systems we created. Despite
our lack of awareness and prepara-
tion, we are now facing an undeni-
able reality: the software community
must learn to design for, monitor,
and manage the energy usage of
software. For this reason, we argue
the need for energy-aware software
and present a manifesto describing
nine guiding principles. By energy-
aware software, we mean software
that is consciously designed and de-
veloped to monitor and react to en-
ergy preferences and usage. Energy
efficiency is, therefore, one possible
(but not the only) response to being
energy aware.
This manifesto and the principles
it proposes have arisen from our ex-
perience and from the experience of
more than 100 researchers and prac-
titioners who have participated in
six international workshops on the
engineering of green and sustainable
software.2 Why do we need a mani-
festo? Why now? Although there has
been some attention to this area,3 we
believe it has been grossly insuffi-
cient given the high stakes involved.
The vast majority of practitioners
(and researchers) are completely ig-
norant of energy concerns; they, and
the programs they create, are any-
thing but energy aware.4
The Nine Principles
of Energy Awareness
Energy awareness is a necessary but
not sufficient precondition for en-
ergy efficiency. Energy awareness
is required from all stakeholders,
such as end users who may choose
product A versus product B based
on energy characteristics. Our goal in
this manifesto is to call for changes
in how we think and what we do.
This will not come for free, but we
believe that the cost of inaction is
far greater.
Public Awareness Is Key for
Widespread Adoption
We believe that the key to widespread
adoption of energy-aware software
is to sensitize and empower end us-
ers. The scary statistics regularly
published have proven ineffective so
far (the amount of energy being con-
sumed by ICT, the increasing amount
of energy consumed by cloud provid-
ers, the massive amounts of data be-
ing stored in data centers as opposed
to the negligible percentages of data
being actually used, and so forth).
Neither do the worrisome energy-
consumption predictions seem to spur
us to action (such as the increasing
number of things being connected to
the Internet or the booming growth
in mobile devices and their increas-
ingly sophisticated applications).
We need to turn these alarming
trends into an opportunity: 1) to sen-
sitize end users to the amount of en-
ergy consumed by the software they
use and 2) to create awareness of
A Manifesto for
Energy-Aware Software
Alcides Fonseca, Rick Kazman, and Patricia Lago
Digital Object Identifier 10.1109/MS.2019.2924498
Date of current version: 22 October 2019
Alcides Fonseca and Rick Kazman and
Patricia Lago. (2019). A Manifesto for
Energy-Aware Software. IEEE Software,
36(6), 79–82
Andrikopoulos, V., & Lago, P. (2021).
Software Sustainability in the Age of
Everything as a Service. In Next-Gen
Digital Services. A Retrospective and
Roadmap for Service Computing of the
Future (pp. 35-47). LNCS, Springer, Vol.
12521
Software Sustainability in the Age
of Everything as a Service
Vasilios Andrikopoulos1(B)
and Patricia Lago2,3
1
University of Groningen, Groningen, The Netherlands
v.andrikopoulos@rug.nl
2
Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
p.lago@vu.nl
3
Chalmers University of Technology, Gothenburg, Sweden
Abstract. The need for acknowledging and managing sustainability as
an essential quality of software systems has been steadily increasing over
the past few years, in part as a reaction to the implications of “software
eating the world”. Especially the widespread adoption of the Everything
as a Service (*aaS) model of delivering software and (virtualized) hard-
ware through cloud computing has put two sustainability dimensions
upfront and center. On the one hand, services must be sustainable on
a technical level by ensuring continuity of operations for both providers
and consumers despite, or even better, while taking into account their
evolution. On the other hand, the prosuming of services must also be
financially sustainable for the involved stakeholders.
In this work, we discuss the need for a software architecting approach
that encompasses in a holistic manner the other two dimensions of soft-
ware sustainability as well, namely the social and environmental aspects
of services. We highlight relevant works and identify key challenges still
to be addressed in the context of software systems operating across differ-
ent models for cloud delivery and deployment. We then present our vision
for an architecting framework that allows system stakeholders to work in
tandem towards improving a set of sustainability indicators specifically
tailored for the *aaS model.
Keywords: Software sustainability · *aaS · Cloud computing ·
Software architecture · Vision
1 Introduction
The last decades have generated an increasing awareness of the need for a more
sustainable world that is at the same time increasingly being run by software sys-
tems [13]. Sustainability can be defined under two lenses as discussed in [16]: that
of sustainable use of a system with regard to a function over a time horizon, and
that of sustainable development that meets current needs without compromising
the ability of future generations to do the same. Computing in general, and soft-
ware in particular has the potential to enable sustainability across the societal
c
! Springer Nature Switzerland AG 2021
M. Aiello et al. (Eds.): Papazoglou Festschrift, LNCS 12521, pp. 35–47, 2021.
https://doi.org/10.1007/978-3-030-73203-5_3
Gupta, S., Lago, P., & Donker, R. (2021).
A Framework of Software Architecture
Principles for Sustainability-driven Design
and Measurement. In 18th International
Conference on Software Architecture
Companion (ICSA-C), pp. 31-37, IEEE
A Framework of Software Architecture Principles
for Sustainability-driven Design and Measurement
Sarthak Gupta
Vrije Universiteit Amsterdam
The Netherlands
Patricia Lago
Vrije Universiteit Amsterdam, The Netherlands &
Chalmers University of Technology, Sweden
Roel Donker
CGI Group,
The Netherlands
Abstract—Aviation connects our world by efficiently and
rapidly moving people, opening new economic opportunities and
transporting food and goods globally. But the notable growth of
air travel in recent years has led to increasingly crowded airspace.
According to the 2019 European Aviation Environment Report,
aviation is responsible for about 3% of global CO2 emissions,
which translates into a big ecological impact. It is imperative
to steer the aviation industry towards optimizing resources, re-
ducing costs, improving decision-making and increasing systems’
resilience to unexpected events.
In this work, we study the sustainability impact of software
architecture principles at Amsterdam Schiphol Airport. To this
aim, we create a framework that relates architecture principles
with sustainability concerns, with the aim of seeking the right
balance toward a positive impact on the sustainable development
of the organization and its services. We combine techniques like
OGSM and Decision Maps to extend the current architecture
principles, and elicit Key Performance Indicators from current
industrial practice.
The resulting framework is the first step towards adopting
sustainability in architecting and laying the foundation to monitor
the effectiveness of the implemented architecture principles on
the target sustainability goals of the organization.
Index Terms—Software Architecture; Architecture Principles;
Sustainability; Aviation Industry; Key Performance Indicators.
I. INTRODUCTION
The aviation industry has always been seeking technological
progress that optimizes the economic, operational and environ-
mental implications of flying. Global demand for aviation has
increased substantially since the first commercial jet airliner
went into service in the 1950s. Since then, demand has risen
9% per year [1]. The aviation industry has always been re-
garded as one of the major contributors to global warming and
pollution. In 2018, CO2 emissions totalled 747 million tonnes
for passenger transport, for 8.5 trillion revenue passenger
kilometers (RPK), giving an average of 88 gram CO2 per RPK
[2]. Over the years, the airliners have become aware of their
societal responsibility to reduce carbon emissions, and several
initiatives such as the Paris Agreement and the Aviation Action
Plan have been launched aiming for a sustainable future with
ICT playing a major role [3].
A software architecture is defined as the “fundamental
organization of a system embodied in its components, their
relationships to each other, and to the environment, and the
principles guiding its design and evolution” [4]. Accordingly,
enterprise architecture can be defined as the fundamental
organization of an enterprise embodied in its components, their
relationships to each other, and to the environment, and the
principles guiding its design and evolution. Adding to that,
Lindström [5] defines architecture principles as the underlying
general rules and guidelines for the use of IT resources across
the organization. In the IT departments of airlines and air-
ports, architecture principles are defined to provide boundaries
and guidelines for IT development; approved by enterprise
architects, and applied in solution architecture. Examples of
architectural principles are: “SAAS over PAAS over IAAS
over on-premise” or “reuse over buy over custom-build”.
Software architecture principles for sustainable development
have, so far, not been given prime importance within airline
and airport organizations. To this aim, we must understand
the impact of the current and future software architecture
principles on sustainability goals.
Worldwide, the demand for aviation doubles every 15 years
[6]. The aviation sector itself is responsible for about 3% of
global CO2 emissions globally, and 7% of the emissions of
The Netherlands [7] – where this study was performed. The
demand for aviation has outpaced the efficiency of the activ-
ities of the sector and as a result, no absolute CO2 reduction
has been realised. As aviation enters a post-pandemic world
and begins recovery, minimizing costs wherever possible and
keeping up with innovation and changes in technology will be
imperative for the aviation industry to bounce back. Improving
the IT infrastructure with more effective principles aimed
towards positive sustainable development and maintaining the
corporate social responsibility, with a balance in all four
dimensions of sustainability (i.e., technical, environmental,
social and economic [8]), would help the Schiphol airport
operated by Schiphol Group to achieve their aim to be zero-
emission and zero-waste by 2030.
The main focus of this research is to understand how the
architecture principles defined by an organization can have an
impact on its sustainable development, and its contribution to
global sustainability. The research has been carried out in the
context of the Royal Schiphol Group for Amsterdam Schiphol
Airport in the Netherlands, which provided the architecture
principles specific to the organization’s data, strategy, princi-
ples and future architecture plans.
The paper presents our study, which has resulted in a frame-
work of software architecture principles, which are meant
to support sustainability-driven design and measurement. In
collaboration with the architects and IT experts in Schiphol,
2021
IEEE
18th
International
Conference
on
Software
Architecture
Companion
(ICSA-C)
|
978-1-6654-3910-7/20/$31.00
©2021
IEEE
|
DOI:
10.1109/ICSA-C52384.2021.00012
Verdecchia, R., Lago, P., & de Vries, C. (2021). The
LEAP Technology Landscape: Lower Energy
Acceleration Program (LEAP) Solutions, Adoption
Factors, Impediments, Open Problems, and Scenarios.
https://tinyurl.com/leap-tech-landscape
0740-7459/21©2021IEEE N OV E M BE R /D ECE M BE R 2021 | IEEE SOFTWARE 7
Editor: Christof Ebert
Vector Consulting Services
christof.ebert@vector.com
SOFTWARE
TECHNOLOGY
SOFTWARE AND IT usage are con-
tinuously growing to keep our soci-
ety active and manage our individual
lives. But as they grow, their energy
demand is exploding. By 2030, data
centers alone will already consume
some 10% of the global electricity.1
Including the Internet, telecommuni-
cations, and embedded devices, the
energy consumption will be one-third
of the global demand. Understanding
that end users only consume what we
offer, it is the community of software
developers who must become active
in ecologic behaviors. Green IT is the
call of today. Each single line of code
that we develop today may still be
running years from now on zillions of
processors, eating energy and contrib-
uting to global climate change.
Green IT and green coding de-
scribe a paradigm switch in which
software engineers, developers, tes-
ters, and IT administrators can make
their solutions and services more en-
ergy efficient. Every single software
person can contribute. In this article,
we provide hands-on guidance on
how to reduce the energy waste of
your software and thus contribute to
more ecologic behaviors.
Green IT
With the introduction of high-band-
width data transfers, affordable data
plans, the generalized migration of
software applications and data man-
agement to the cloud, the wide usage
of streaming services, and, obviously,
the many embedded computers
in our everyday lives, digital infra-
structures are experiencing an ever-
growing demand for energy. While
digital transformation looks impres-
sive from an economic perspective,
it has its downside on the ecologic
footprint of these businesses.
An immediate action is to adopt
more renewable energy. Energy-hun-
gry companies such as Microsoft,
Google, and Amazon are currently
investing in water energy, for exam-
ple, to cool their data centers; solar
energy; and wind farms. Many com-
panies engage in trading CO2 cer-
tificates to give a green color to the
energy waste of their data centers.
But renewable energy only “cures”
the symptoms. It does not really
solve reducing the need for energy.
Digital Object Identifier 10.1109/MS.2021.3102254
Date of current version: 22 October 2021
Green IT and
Green Software
Roberto Verdecchia and Patricia Lago, Vrije Universiteit Amsterdam
Christof Ebert, Vector Consulting Services
Carol de Vries, PhotonDelta
From the Editor
Ecologic behavior is the need across the world to mitigate the impacts of climate
change. Software and IT play a pivotal role toward ecologic behaviors for many rea-
sons. Being aware that IT systems alone already consume 10% of global electricity, the
leading software practitioners must embark on green IT and green coding. Read in
this article about hands-on guidance on how you can contribute toward more ecologic
software. I look forward to hearing from you about this column and the technologies
that matter most for your work.—Christof Ebert
Verdecchia, R., Lago, P., Ebert, C., & De
Vries, C. (2021). Green IT and Green Software.
IEEE Software, 38(6), 7-15

Want to know more? … on visualization of impacts
Verdecchia, R., Lago, P., Malavolta, I.,
& Ozkaya, I. (2020). ATDx: Building an
Architectural Technical Debt Index. In R.
Ali, H. Kaindl, & L. Maciaszek (Eds.),
ENASE 2020: Proceedings of the 15th
International Conference on Evaluation
of Novel Approaches to Software
Engineering (pp. 531-539). SciTePress.
Ospina, S., Verdecchia, R., Malavolta, I.,
& Lago, P. (2021). ATDx: A tool for
providing a data-driven overview of
architectural technical debt in software-
intensive systems. In ECSA 2021
Companion
https://github.com/S2-group/ATDx
ATDx: Building an Architectural Technical Debt Index
Roberto Verdecchia1
, Patricia Lago1
, Ivano Malavolta1
, and Ipek Ozkaya2
1Vrije Universiteit Amsterdam, The Netherlands
2Software Engineering Institute, Carnegie Mellon University, USA
{r.verdecchia, p.lago, i.malavolta}@vu.nl, ozkaya@sei.cmu.edu
Keywords: Software Architecture, Technical Debt, Software Analytics, Software Metrics, Software Maintenance
Abstract: Architectural technical debt (ATD) in software-intensive systems refers to the architecture design decisions
which work as expedient in the short term, but later negatively impact system evolvability and maintainability.
Over the years numerous approaches have been proposed to detect particular types of ATD at a refined level
of granularity via source code analysis. Nevertheless, how to gain an encompassing overview of the ATD
present in a software-intensive system is still an open question. In this study, we present a multi-step approach
designed to build an ATD index (ATDx), which provides insights into a set of ATD dimensions building
upon existing architectural rules by leveraging statistical analysis. The ATDx approach can be adopted by
researchers and practitioners alike in order to gain a better understanding of the nature of the ATD present in
software-intensive systems, and provides a systematic framework to implement concrete instances of ATDx
according to specific project and organizational needs.
1 INTRODUCTION
Architectural Technical Debt (ATD) in a software-
intensive system denotes architectural design choices
which, while being suitable or even optimal when
adopted, lower the maintainability and evolvability of
the system in the long term, hindering future develop-
ment activities [Li et al., 2015b]. With respect to other
types of debt, e.g., test or build debt [Li et al., 2015a],
ATD is characterized by being widespread throughout
code-bases, mostly invisible [Kruchten et al., 2012],
and of high remediation costs.
Due to its impact on software development prac-
tices, and its high industrial relevance, ATD is attract-
ing a growing interest within the scientific commu-
nity and software analysis tool vendors [Verdecchia
et al., 2018]. Notably, over the years, numerous ap-
proaches have been proposed to detect, mostly via
source code analysis, ATD instances present in soft-
ware intensive-systems. Such methods rely on the
analysis of symptoms through which ATD manifests
itself, and are conceived to detect specific types of
ATD by adopting heterogeneous strategies, ranging
from the inspection of bug-prone components [Xiao
et al., 2016], to the analysis of dependency anti-
patterns [Arcelli Fontana et al., 2017], maintainability
issues [Malavolta et al., 2018], and the evaluation of
components modularity [Martini et al., 2018b]. Addi-
tionally, numerous static analysis tools, such as NDe-
pend1, CAST2, and SonarQube3, are currently avail-
able on the market, enabling to keep track of tech-
nical debt and architecture-related issues present in
code-bases. Both academic and industrial approaches
currently focus on fine-grained analysis techniques,
considering ad-hoc definitions of technical debt and
software architecture, in order to best fit their anal-
ysis processes. Nevertheless, to date, how to gain an
encompassing overview of the (potentially highly het-
erogeneous) ATD present in a software-intensive sys-
tem is still an open question.
In order to fill this gap, in this study we present
ATDx, an approach designed to provide data-driven,
intuitive, and actionable insights on the ATD
present in a software-intensive system. ATDx con-
sists of a theoretical, multi-step, and semi-automated
process, concisely entailing (i) the inclusion of archi-
tectural rules supported by pre-existing analysis tools,
(ii) the identification of outlier values (after normal-
ization) via statistical analysis, and (iii) the aggrega-
tion of analysis results into a set of customizable ATD
dimensions. ATDx is meant to serve two types of
stakeholders: (i) researchers conducting quantitative
studies on source-related ATD and (ii) practitioners
carrying out software portfolio analysis and manage-
ment, to suitably detect ATD items and get actionable
1https://www.ndepend.com
2https://www.castsoftware.com/
3https://www.sonarqube.org
ATDx: A tool for Providing a Data-driven Overview
of Architectural Technical Debt in So�ware-intensive
Systems
Sebastian Ospina1
, Roberto Verdecchia1
, Ivano Malavolta1
and Patricia Lago1,2
1
Vrije Universiteit Amsterdam, The Netherlands
2
Chalmers University of Technology, Gothenburg, Sweden
Abstract
Architectural technical debt (ATD) in software-intensive systems is mostly invisible to software de-
velopers, can be widespread throughout entire code-bases, and its remediation cost is often steep. In
recent years, numerous approaches have been proposed to identify, keep track, and ultimately manage
ATD. The variety of approaches available opens a new problem, namely how to gain an encompassing
overview of the ATD identi�ed in a software-intensive system. With this paper we make available the
ATDx tool, an implementation of ATDx written in Python, designed in a plug-in fashion. ATDx is an
approach designed to provide a data-driven, intuitive, and actionable overview of the ATD present in
a portfolio of software projects. ATDx is based on third-party source code analysis tools, architectural
issue severity calculation via clustering, and aggregation of measurements into di�erent architectural
technical debt dimensions. The ATDx tool allows users to automatically run the ATDx analysis, gener-
ate reports containing the ATDx analysis results, and is integrated with GitHub. In addition to the tool,
we provide two already implemented plugins, allowing users to run the ATDx tool out-of-the-box.
GitHub repository: https://github.com/S2-group/ATDx
Video: https://youtu.be/ULT9fgxuB7E
Keywords
Software Engineering, Software Architecture, Technical Debt, Index, Tool
1. Introduction
Context. Architectural Technical Debt (ATD) in a software-intensive system encompasses all
architectural design or implementation constructs that, while being suitable today, will lower
the maintainability and evolvability of the system in the long term. ATD is mostly invisible
to software developers, can be widespread throughout entire code-bases, and its remediation
cost is often steep [1]. Tool support can aid software practitioners by providing automated and
semi-automated approaches to systematically identify, keep track, and ultimately manage ATD.
In recent years numerous �ne-grained approaches, leveraging di�erent de�nitions of ATD, have
ECSA’21: European Conference on Software Architecture, September 12–17, 2021, Virtual
� s.ospinacamacho@vu.nl (S. Ospina); r.verdecchia@vu.nl (R. Verdecchia); i.malavolta@vu.nl (I. Malavolta);
p.lago@vu.nl (P. Lago)
� https://robertoverdecchia.github.io/ (R. Verdecchia); http://www.ivanomalavolta.com/ (I. Malavolta);
http://patricialago.nl/ (P. Lago)
� 0000-0001-9206-6637 (R. Verdecchia); 0000-0001-5773-8346 (I. Malavolta); 0000-0002-2234-0845 (P. Lago)
© 2021 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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Thank you
Credits: slides, ideas and results are a collective effort with my
bright and energetic colleagues in the S2 Group
@Vrije Universiteit Amsterdam s2group.cs.vu.nl
Download our papers from the S2 VU Research Portal
Check out what we teach: s2group.cs.vu.nl/pages/courses
My virtual presence: www.patricialago.nl

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