A Service Definition for Data Portability
Dominik Huth, Laura Stojko and Florian Matthes
Chair of Software Engineering for Business Information Systems, Technical University of Munich, Boltzmannstr. 3,
Garching, Germany
Keywords:
GDPR, Privacy Engineering, Soft Privacy, Data Portability, Service Definition, Information Model.
Abstract:
Data portability is one of the new provisions that have been introduced with the General Data Protection
Regulation (GDPR) in May 2018. Given certain limitations, the data subject can request a digital copy of
her own personal data. Practical guidelines describe how to handle such data portability requests, but do not
support in identifying which data has to be handed out. We apply a rigorous method to extract the necessary
information properties to fulfill data portability requests. We then use these properties to define an abstract
service for data portability. This service is evaluated in seven expert interviews.
1 INTRODUCTION
After a two-year period of discussion and preparation,
the General Data Protection Regulation (GDPR) (Eu-
ropean Union, 2016) is finally being enforced since
May 2018. It introduced updated definitions for per-
sonal data and the territorial scope, enhanced data
subject rights, the adoption of privacy by design and
default, and extended responsibilities for data proces-
sors (Tikkinen-Piri et al., 2017). Even though the first
wave of attention for the GDPR has settled, many
companies still lack the resources (or, in some cases,
the willingness) to become fully compliant. In fact,
the first fines based on the new regulation are now
under way (Allen, 2018) and further incidents are ex-
pected. Research on methods and tools to deal with
GDPR requirements is all but finished.
A new right established with the GDPR is data
portability (Article 20). The data subject now has
the right to ”receive the personal data concerning
him or her [...] in a structured, commonly used and
machine-readable format” and the right to ”trans-
mit those data to another controller” or ”have the
personal data transmitted directly” (European Union,
2016).
Researchers identify a series of challenges for the
implementation of data portability. As a right af-
fecting both privacy legislation and competition law,
companies are hesitant in supporting the migration of
their customers to a competitor (Vanberg and
¨
Unver,
2017) and portability standards are missing (Bistolfi
et al., 2016). However, data portability could also
help in creating a new kind of data economy where
data subjects leverage their data in multiple organiza-
tions (De Hert et al., 2017).
The research goal of this paper is to further ad-
vance the information extraction according to Art. 20
GDPR. We will accomplish this goal with the follow-
ing research questions:
RQ1: What are the information requirements for
the fulfillment of Art. 20 GDPR?
RQ2: How can a data gathering service be de-
fined?
RQ3: How useful or applicable is the approach
proposed in this paper?
2 RESEARCH OUTLINE
In this section, we present our research process for de-
veloping and assessing the service definition for data
portability.
First, we shortly survey prominent work of the Pri-
vacy Engineering field and position our work within
the established frameworks for matching require-
ments and technical approaches in section 3.
To answer RQ1, we apply an established method
called semantic parametrization (Breaux et al., 2006)
to conduct a thorough analysis of the legal provisions
within Art. 20 GDPR. From the resulting semantic
model of the regulation, we conduct a further analy-
sis to extract the necessary properties for identifying
Huth, D., Stojko, L. and Matthes, F.
A Service Definition for Data Portability.
DOI: 10.5220/0007677101690176
In Proceedings of the 21st International Conference on Enterprise Information Systems (ICEIS 2019), pages 169-176
ISBN: 978-989-758-372-8
Copyright
c
2019 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
169
data that is subject to data portability. This process is
described in section 4.
Data portability is then defined as an abstract,
platform-independent service fulfilling the require-
ments identified with RQ1. An information model
describes the abstract representation of data structures
with personal data. We specify a process for respond-
ing to data portability requests and demonstrate the
process using a well-known data model in section 4,
answering RQ2.
RQ3 is addressed through seven qualitative, semi-
structured interviews with IT experts in various po-
sitions of multiple organizations. The interviews are
described in detail in section 7.
We discuss our findings and additional outcomes
regarding the experts’ opinion on the GDPR and state
possible future research directions in section 8.
3 POSITIONING IN PRIVACY
ENGINEERING CONTEXT
The field of Privacy Engineering, as defined by
(G
¨
urses and Del Alamo, 2016), focuses on systemat-
ically capturing and addressing privacy issues in sys-
tem engineering processes. This is a particular chal-
lenge, since the word privacy generally serves a an
umbrella term for a set of related problems (Solove,
2007), and thus does not contribute to a clear picture
of the necessary actions. In an engineering context,
eliciting privacy requirements equates to identifying
properties that need to be fulfilled or prevented when
designing a system.
For privacy requirement elicitation, (Notario et al.,
2015) identify two complimentary approaches: the
top-down or goal-based approach, where desirable
privacy properties serve as the starting point; and
the bottom-up or risk-based approach, which analy-
ses a system design for exposure to non-desirable out-
comes or anti-goals.
An example for a top-down approach is the
PriS method (Kalloniatis et al., 2008), which de-
fines the desirable properties Authentication, Autho-
rization, Identification, Data Protection, Anonymity,
Pseudonymity, Unlinkability and Unobservability,
which are addressed by so-called privacy process pat-
terns. This method does not specifically address data
subject rights, such as data portability requests. We
will define a process pattern for such requests later in
this paper, which also refers to the process pattern of
authentication.
On the opposite side, the LINDDUN method
(Deng et al., 2011) is an example for a risk based
approach. It was developed as a privacy analogy to
Microsoft’s STRIDE method for identifying security
threats (Microsoft, 2009) and focuses on anti-goals
in the privacy domain.
1
The authors categorize pri-
vacy goals into hard privacy and soft privacy and as-
sign the corresponding anti-goals to these two cate-
gories. Linkability, Identifiability, Non-repudiation,
Detectability and Information Disclosure are cate-
gorized as hard privacy anti-goals, whereas Content
Unawareness and Policy and consent Noncompliance
belong to the soft privacy category. Similarly, (Spiek-
ermann and Cranor, 2009) distinguish between pri-
vacy by policy and privacy by architecture. After elic-
iting the privacy requirements, countermeasures are
matched to the identified risks.
In this work, we focus on the soft privacy goal of
content awareness. In order to make informed deci-
sions about sharing (or continuing to share) personal
information with a controller, a data subject has to
be aware of which personal information is being pro-
cessed. In some cases, such as credit ratings or health
information, it is important to ensure accuracy of the
data and, subsequently, prevent erroneous decisions.
The right of access and the right to rectification are
crucial for this function.
With the enhancement of data subject rights and
the introduction of data portability in the GDPR,
there is also a need to develop methods to respond to
these privacy requirements systematically. Since we
do not see corresponding countermeasures or mitiga-
tion strategies within the established frameworks, we
would like to advance the view that the implementa-
tion of data subject rights should be included in pri-
vacy engineering frameworks. This work constitutes
the first step in this direction.
Nonetheless, there is already some practical ad-
vice available for how to handle data portability re-
quests. The Article 29 Working Party was established
as an independent advisory body to the European
Union and is formed by European data protection of-
ficers. Their “Guidelines on the right to data porta-
bility” (Article 29 Data Protection Working Party,
2017) discuss under which conditions data portabil-
ity applies, what data must be included and how and
in which formats it should be provided. Although
this document addresses many important questions,
to the best of the authors’ knowledge, there is no ser-
vice definition available on how relevant data for data
portability can be identified.
1
The acronym LINDDUN, just like the acronym
STRIDE, is composed from the initial characters of the anti-
goals.
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4 REQUIREMENT ANALYSIS
(Breaux et al., 2006) identify a mismatch between re-
quirements specified in legal provisions and actual
system requirements. To bridge this gap, the au-
thors establish a process called semantic parametriza-
tion. It comprises the steps policy selection, goal
mining, identification of restricted natural language
statements (RNLS) and semantic modeling, which we
will describe for Art. 20 in the following paragraphs.
Additionally, we extracted the necessary information
items from the resulting semantic model. These in-
formation items represent the information that needs
to be accounted for when gathering data for a request
pursuing Art. 20 GDPR. The process is visualized in
Figure 1.
The process starts with the policy selection, which
is Art. 20 GDPR in our case. In the goal mining step,
the natural language statements within Art. 20 are
reformulated into single goals, e.g.
“The data subject shall have the right to re-
ceive the personal data concerning him or her,
which he or she has provided to a controller,
in a structured, commonly used and machine-
readable format”
is restated into goals which are exemplified in Ta-
ble 1. This yields a list of 16 unique goals for Article
20. Since some of the goals refer to other articles (i.e.
Art. 6, Art. 9 and Art. 17), semantic parametriza-
tion was applied to these articles as well, but is not
displayed here.
Table 1: Example for goals within Art. 20 GDPR.
Actor Action Subject Type Conditions
DS Receive
Personal
Data
Concerning
him or her
DC Provide
Personal
Data
Provided by
Data Subject
The third step in the semantic parametrization is the
phrasing of RNLS, which are defined to have exactly
one actor, one action and one or more objects. More
complicated goals are split into multiple RNLS with
references to each other. A network of dependencies
among the RNLS of Art. 20 and referenced articles is
shown in Figure 2.
As the final result of the process described by
Breaux, we obtained a semantic model representation.
This semantic model consists of atomic elements, cat-
egorized as rights or obligations for the data subject
or the data controller. Analyzing each of these ele-
ments, we identified the following list of information
requirements for the data controller:
personal data concerning the data subject
processing based on consent
processing based on explicit consent
processing based on a contract
special categories of personal data
erasure date
processing in the public interest
Note that there are two information items pro-
cessing based on consent and the stronger condition
processing based on explicit consent. This reflects
the distinction the regulation makes between personal
data and special categories of personal data, which are
sensitive in relation to fundamental rights and free-
doms. The special nature of the data has to be pointed
out when obtaining consent.
5 DATA PORTABILITY SERVICE
DEFINITION
In this section, we first briefly explore the concept of
platform-independent service design, which we resort
to for the definition of our data portability service.
We then specify the generalized information model
from which we intend to extract the information items
we identified in section 4. Lastly, we define the data
portability service as a business process.
5.1 Service-orientation
A service is the behavioral description of a system
without limitations on its internal structure (Almeida
et al., 2003). In a setting as diverse as the collection
of personal information, this concept is particularly
well-suited for the data portability requirements. An
example for the platform-independent service design
is given by (Almeida et al., 2003) and displayed in
figure 3 as systematic design approach.
One milestone is the platform-independent ser-
vice design. This phase contains the platform-
independent service logic by using service compo-
nents and abstract-platform definitions. Especially,
the portability requirements of the characteristics of
the platform have to be taken into consideration.
The last milestone is the platform-specific ser-
vice design which contains platform-specific service
components and a concrete platform definition. In
case the abstract platform definition does not differ
A Service Definition for Data Portability
171
Figure 1: Semantic parametrization with additional steps.
Figure 2: Network of RNLS of Art. 20.
Figure 3: Platform-independent Service Description
(Almeida et al., 2003).
from the platform chosen, the transfer from platform-
independent to platform-dependent service design can
be done easily.
5.2 Information Model
For the development of the information model as a
basis for the data portability service, the platform-
independent service design (Almeida et al., 2003) is
used. Thus, an information model should describe
a service which follows the systematic approach of
platform-independent service design. In this case, the
service definition contains the definition of necessary
information to fulfill data portability GDPR Art. 20
and the definition of how this data can be gathered
from an abstract point of view.
Besides the abstraction level, the information model
focuses on business objects which are defined as
“A business object is defined as a passive el-
ement that has relevance from a business per-
spective. (The Open Group, 2013)
According to (Hess et al., 2006), there should be a
business object type distinction between fast changing
business objects (transaction data) and slowly chang-
ing business objects (master data). An example for
master data is customer data like the name, address,
date of birth, etc. as it is rarely updated by the cus-
tomer. Transaction data is orders and invoices, as this
data is changing and growing steadily - depending on
the users’ behaviour. For the fulfillment of GDPR Art.
20, a distinction of master data and transaction data
of business objects is necessary as it contains differ-
ent efforts of extracting the information to fulfill the
requirements (Lewinski et al., 2018).
Considering the abstraction level and business ob-
ject definition, the information model is displayed in
Figure 4.
Figure 4: Data Gathering Service accessing Data Portability
Information Model at Business Subject.
Business Subject: A Business Subject is a type
of business object which is stored as master data.
Examples for a Business Subject are product or
customer records. In this paper, Business Sub-
jects which are directly related to a person, such
as a customer’s record, are in focus. We regard
business subject data as master data.
Business Entity: A Business Entity is a type of
business object which is created by and directly
connected to a Business Subject. In other words
transaction data (e.g. invoices, orders).
GDPR Data Gathering Service: This service is
an integration layer which requests data sources
of the required information for the data transfer.
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5.3 Data Portability Service
The data portability service is described by a process,
which is displayed in Figure 5 and explained in this
section.
The first step is the creation of a request by the
data subject. Then, this request has to be verified
by the data controller. Therefore, the request will be
valid if it is created on the basis of the GDPR and not
under country-specific regulations. Further, the data
subject has to be authenticated and their request au-
thorized.
If the request is valid, the next step is to iden-
tify the relevant data. For this purpose, the GDPR
data gathering service collects all relevant data. This
data gathering subprocess starts at the business sub-
ject which is related to the requester. Further, it iter-
ates over adjacent business entities. Finally, each en-
tity attribute is verified with respect to the relevance
for complying with data portability (Section 4).
After summarizing the data gathering subprocess
output, the resulting data needs to be returned se-
curely to the requester. With the submission of the
data report to the data subject, the data controller fin-
ishes its required work to comply with data portability
according to Art. 20 of the GDPR.
6 TWITTER EXAMPLE
To ensure the understanding of the proposed process,
we exemplify the approach with the help of the so-
cial network Twitter. In Figure 6, we show how the
GDPR Data Gathering Service accesses the Twitter
data model (Neppelenbroek et al., 2011) at the User
element, which is its root node.
In this case, the business subject is the class User
and the relevant business entities are List, Message
and Tweet. The latter one refers further to the business
entities HashTag and UserTag.
The process starts with a request by a user who
demands a report according to data portability GDPR
Art. 20. In the case of Twitter, this is most done
within an online account.
The next step by the data controller is to verify
this request. Thus, the user has to be authenticated
and the request authorized. In the case of an online
account, the user is already authenticated. In other
cases, the controller might ask for different modes of
authentication.
After verifying the request, the data controller has
to gather the required data to comply with data porta-
bility. Therefore, the data gathering service starts at
the business subject of the identified user. With the
list of properties from section 4, the attributes of User
are checked. UserID, Mobile, Notices and Profile are
identified as relevant for Art. 20 (shown in bold font
in Figure 6). Then, we iterate over the adjacent enti-
ties, i.e. other Users (that are being followed), Lists,
Messages, Tweets and so on. For each entity the crite-
ria from Section 4 are checked again. Combining all
this information yields the data that has to be trans-
ferred to the data subject.
Finally, the data report of the user’s provided in-
formation is returned securely to the data subject. In
the case of Twitter, this is done as a download link for
an authenticated account.
Now, the data subject can use this report for
switching to another data controller or as overview of
the information she provided to Twitter.
7 EVALUATION
For the evaluation of the service for data portability
and the underlying information model, seven expert
interviews were conducted. An overview of the inter-
viewees is displayed in Table 2.
Each interview started with an introduction of the
interviewee and the problem domain. To ensure the
expert’s understanding, an example for the service in-
stantiation was given. Then, the experts were asked to
evaluate the underlying information model according
to Lindland’s criteria (Lindland et al., 1994).
The first quality criterion is the syntactic quality
which discusses the realization of the modeling lan-
guage used within the model. Next, the semantic
quality describes the validity and completeness of the
model with respect to the problem domain. Finally,
the pragmatic quality is about the interpretation of the
model by the stakeholders and the objective of com-
prehensibility.
After the discussion of the information model’s
quality, the experts were asked open questions re-
garding the usage and application within the service
we described. After each interview, the information
model was adjusted according to the reasonable en-
hancements or changes suggested by the experts. The
updated information model was then used in the fol-
lowing expert interview. Using this procedure, the
service definition was developed iteratively.
The following paragraphs summarize the most im-
portant interview outcomes.
How do you evaluate the syntactic, semantic
and pragmatic quality of the information model?
Regarding the information model, the syntactic
and semantic quality improved iteratively as the ad-
dressed suggestions were added to the information
A Service Definition for Data Portability
173
Figure 5: Process of a Data Portability Request.
Table 2: Overview of Interviewees.
ID Current profession Company size Industry
1 Cyber Security Portfolio Manager large enterprise Industrial Manufacturing
2 Head of IT Strategy large enterprise Industrial Manufacturing
3 Co-Founder Compliance Tool Start-Up IT Service & Consulting
4 Corporate Data Privacy Officer large enterprise Industrial Manufacturing
5 Cyber Security Architect large enterprise Industrial Manufacturing
6 Head of Sales for Privacy Management Tool SME IT Service & Consulting
7 Business Intelligence (2) large enterprise Finance
Figure 6: Data Gathering Service applied to the Twitter data
model (information to be extracted in bold font).
model. In the end, the modeling language, syntax
and the validity and completeness with respect to the
problem domain were rated as good. Especially the
distinction between master and transaction data was
mentioned as advantage by experts 1, 3 and 6. An in-
teresting point mentioned by interviewees 2 and 6 is
the advantage regarding the abstraction level as they
agree to the point that a more detailed information
model would not be platform independent. Thus, the
service definition from section 5 is suitable. However,
the abstraction level was regarded as disadvantage to
the pragmatic quality. Due to missing implementation
details, experts 1, 2, 3 and 4 refer to the problem that
it is hard to understand how to take advantage and
realize the information model. Nevertheless, some
experts (5, 6, 7) already mentioned implementation
ideas, e.g. to enhance the Electronic Data Interchange
(EDI) with a plausibility check or connect a query to
the Data Warehouse.
What do you think about the feasibility of a
data gathering service for data portability automa-
tion?
With respect to the application of the data porta-
bility service, the interviewees 2, 3 and 7 recommend
the usage of this service for a greenfield approach
ICEIS 2019 - 21st International Conference on Enterprise Information Systems
174
or in data-driven companies, e.g. social media net-
works. They mention an issue with complex infras-
tructure which would make it difficult to incorporate
an automated procedure for a data portability service.
Notwithstanding, all experts consider the information
model as useful guidance for the application of such
a service. As already mentioned above, the abstrac-
tion level was on the one hand seen as advantage, as it
summarizes the important facts necessary for comply-
ing with data portability, but on the other hand it was
categorized as disadvantage since implementation de-
tails are missing. Further, expert 3 recommends a de-
tailed description of data portability with respect to
one industry. This is one enhancement idea for fur-
ther discussion, as we will discuss in section 8. Inter-
viewees 1, 2, 6 and 7 point out the issue of identify-
ing where the required data is stored. Existing com-
plex IT landscapes or multiple Data Warehouses ham-
per the identification of data location. Thus, the data
flow mapping cannot be done easily, but is required
to comply with the GDPR. For companies with this
issue it is more difficult to apply the data portability
service as described.
How are you handling data portability re-
quests?
According to the experts 1, 2, 4, 5 and 7, they are
managing the requests manually as there are few in-
coming requests for data portability within their com-
pany. Further, there are no existing automated solu-
tions available which can handle their complex infras-
tructure.
8 CONCLUSION & OUTLOOK
In this paper, we have applied the process of semantic
parametrization in order to extract 7 specific informa-
tion for Art. 20 of the GDPR, answering RQ1 from
Section 1.
We then specified a platform-independent service
to respond to data portability requests. The service
makes use of a generalized information model and
takes into account the information requirements that
were identified. This answers RQ2.
To evaluate the usefulness and applicability of our
approach, we conducted 7 expert interviews. The
experts confirmed that a service definition can con-
tribute to the implementation of data portability. In
its current abstract form, it serves as a model to guide
the execution of data portability requests or even as
guidance for implementing an automated solution.
However, according to the experts, economic via-
bility of automated portability largely depends on the
type of business. The companies in our interiews have
to comply with the GDPR and therefore fulfil Art.
20 as well, but since they operate in a B2B context
(industrial and financial sector) or provide services
for SMEs, they are not faced with massive amounts
of data subject requests. This constitutes a limita-
tion of this work, since representatives of companies
whose business models rely heavily on personal infor-
mation were not part of this study. Some companies,
like Facebook and Google, have already implemented
automated solutions to answer data subject requests.
Experts who were involved in these efforts could pro-
vide valuable advice to companies with less public ex-
posure.
The service we defined aligns with current pri-
vacy engineering frameworks, since it addresses the
enhanced requirements in the soft privacy or privacy
by policy area. Definitions and good practices for ful-
filling these requirements can support developers in
implementing compliant architectures.
Further comments from our experts mentioned
that data subjects themselves are generally unaware of
the right to data portability and hence, requests typi-
cally refer to the right of access (Art. 15). Data sub-
jects also lack the knowledge what they have to pro-
vide in order to start a successful data subject request.
Having specified and evaluated a service for data
gathering in compliance with Art. 20 GDPR, we
acknowledge further possible directions of work.
Firstly, the approach could be extended to other ar-
ticles of the GDPR regarding the exercise of data sub-
ject rights. Due to the explicit references in Art. 20
we covered Art. 17 (right to erasure), as well as Art.
6 and Art. 9 (legal bases and preconditions for pro-
cessing special categories of personal data).
Secondly, industry-specific solutions or technical
implementations could be investigated. Such solu-
tions exist in deregulated utilities markets, where con-
sumers port their meter numbers from one utilities
provider to another, and are being developed for sim-
plified data models in social media (Google et al.,
2018). Further studies could investigate the develop-
ment and reasoning of the existing solutions by so-
cial media companies. Another approach led by Tim
Berners-Lee is called Solid, where the goal is to ex-
clusively store personal data in a personal data store.
Applications built on top of Solid never collect per-
sonal data themselves, but are granted access to sub-
sets of this data.
In any case, we expect the importance of data
portability to increase as awareness for the flexibility
it allows in the usage of services gains more attention
among data subjects.
A Service Definition for Data Portability
175
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