Developing Model Transformations: A Systematic Literature Review

Ana Patrícia Magalhães

1,3 a

, Rita Suzana P. Maciel

2 b

and Aline Andrade

2 c

State University of Bahia, Department of Exact Sciences and Earth, 2555 Silveira Martins St. Cabula, Bahia, Brazil

Federal University of Bahia, Computer Science Department, Bahia, Brazil

Salvador University, Post Graduate Program in Computing and Systems, Bahia, Brazil

Keywords: Model Transformation, Development Strategies, Development Process, Modeling Language.

Abstract: Model Driven Development is an approach that makes use of models instead of code in software development.

At its core, there is a transformation chain responsible for the (semi) automation of the development process

converting models into models until code. The development of transformations has been a challenge as there

is an inherent complexity of the transformation domain in addition to the complexity of the software being

constructed using these transformations. In order to assist this development as well as improve transformation

quality, it is important to adopt software engineering facilities such as processes, languages and other

techniques. This paper presents a systematic literature review of strategies currently proposed to develop

model transformations. We aim to investigate development processes or any other strategies used to guide

transformation development, the phases of software development life cycle considered, modeling languages

adopted for specification and also the level of automation provided. The study selected and analyzed 23 papers

to identify which aspects are addressed by research and any gaps in this area. We identified four different

strategies in guiding transformation development and perceived the lack of a modeling language standard.

1 INTRODUCTION

Model Driven Development (MDD) (Mellor,

2004) is a software development paradigm that

makes intensive use of models to represent

systems at different levels of abstraction. At the

core of MDD is a transformation chain which

converts models into other models (model

transformations - MT) and model into text

(program transformation) in order to generate

application code (Stahl, 2010). In this study we

are initially interested in MT development.

The specification of a MT is defined between

metamodels of source and target languages, which

define application domains (Brambilla, 2012). Any

models that are instances of the metamodels can be

processed by the transformation. In general,

developers are used to manipulating models for

software documentation, but they are not used to

working with metamodels, which require

https://orcid.org/0000-0002-8608-4553

https://orcid.org/0000-0003-3159-6065

https://orcid.org/0000-0002-9926-9303

specification at higher abstraction levels than in

models. Moreover, the environments, for both

metamodel implementation and model specification

according to the metamodel, should be adopted to

support MT development. Additionally, model

transformations are usually written in specific

languages, e.g. ATL (Atlas Transformation

Language), which are appropriate for model

manipulation, instead of coded in common program

languages such as C and Java. Therefore, the

development of MT involves expertise in new

languages, the adoption of development

environments customized for these languages and

engines to execute the transformations.

In summary, model transformation development

involves elements that are not common in traditional

software development and this increases its

complexity, such as domain specific modeling

languages, and specific programming languages as

well as comprising metamodel definition and

manipulation. In addition, software, in general, has

become increasingly complex due to the need to work

Magalhães, A., Maciel, R. and Andrade, A.

Developing Model Transformations: A Systematic Literature Review.

DOI: 10.5220/0009380100800089

In Proceedings of the 22nd International Conference on Enterprise Information Systems (ICEIS 2020) - Volume 2, pages 80-89

ISBN: 978-989-758-423-7

with wide domains, integration with other software,

among others, which may also reflect in the size and

complexity of the MT used in its construction.

Therefore, the development of MT requires software

engineering facilities, for example, development

processes, modeling languages, and automation to

achieve quality and improve maintenance and

evolution (Guerra, 2010), (Bollati, 2013).

Initially, MT were usually specified in natural

language and implemented directly in code (Guerra,

2010), (Bollati, 2013). As a consequence, this

hindered the adoption of best practices in software

engineering, such as reuse, which might compromise

its evolution and maintenance. This scenario is

changing and some proposals consider other phases

of the software development life cycle, instead of

only codification. For example, there are works that

focus on design and implementation phases (Del

Fabro, 2009), (Bollati, 2013), (Tavac, 2013), while

others concern formal specification (Sani, 2011).

As there is still no consensus about which

methods and techniques are more appropriate, it is

necessary to understand what strategies are being

used to develop MT in order to obtain a better

understanding and comprehension of current trends in

this area. In this direction, this paper provides a

Systematic Literature Review (SLR) of the strategies

used to guide MT development, i.e. analysis, design

and implementation of MT. SLRs aim to aggregate

knowledge about a software engineering topic or

research technique using a rigorously methodology

review of resource results. They are important to

collect evidence on a particular topic of interest and

support practitioners in developing appropriate

solutions for specific context (Kitchenham, 2004).

This definition and the protocol of Kitchenham are

adopted in our work. Therefore, our review aims to

know how the community is developing MT, i.e.

identify which methods have been used and collect

evidence of its use. The SLR covers the period from

2003 to 2019, including research databases of most

publications related to MDD. We selected and

analyzed 23 works and significant results were

obtained, which are important for both developers

and researchers in need of support in developing

transformation chains e.g. this SLR can help to make

easier the identification of the most used strategies

when a software architect is proposing a new model

transformation approach.

The text is organized as follows: Section 2

introduces some background about MDD; Section 3,

4 and 5 respectively present the research method used

to guide this SLR, its execution and the results

obtained; Section 6 analyzes related works about MT

development. Section 7, discusses the results of the

review identifying some current gaps in MT

development; Section 8 discuss some threats to our

review; and, Section 9 presents our conclusions.

2 BACKGROUND

In MDD, models at high abstraction levels are

converted, through a transformation chain, into

models at a low abstraction level until the application

code is generated. MDD comprises two main

elements: models, which are the artifacts that

represent application at different abstraction levels

and transformations, the software responsible for the

automation of the development (Brambilla, 2012).

Models are abstract representations of a system,

which comprise the structure and behavior (Mellor,

2004). MDD models are not mere documentation of

software, they are the artifacts used as input of the

transformations to generate other models or code.

Thus, they must be defined in modeling languages

with a well-defined syntax and semantic. MDD

usually uses Domain Specific Modeling Languages

(DSML) for model specification. In MDD, the

abstract syntax and the static semantics of a modeling

language are expressed in metamodels. Thus, models

are designed conforming to metamodels. UML, a

general purpose language, can be customized to

specific domains through the definition of UML

profiles to be used as a modeling language in MDD.

In MDD, transformations can be classified

according to the artifact produced as output from

model transformation, when generate models as

output; or program transformation when generates

code as output. A transformation can be seen from

two different viewpoints, as a function that maps

models between domains or as a terminating

algorithm that applies structural and/or semantic

changes to models (Ma, 2016). This work focuses on

the first viewpoint called relational transformation.

Therefore, a MT comprises a set of rules that

describes how models, instances of source

metamodels, are converted into models, instances of

target metamodels (Mens, 2006).

3 RESEARCH METHOD

The SLR reported in this paper follows the guidelines

presented in (Kitchenham, 2004). The Start tool

(Start, 2013) was used to support the process. The

review was performed by three researchers, a Ph.d.

Developing Model Transformations: A Systematic Literature Review

student, and her two supervisors. Extra information

about this SLR can be accessed at

https://drive.google.com/drive/folders/1Vxi2j9-

SfHYbt6YmIaGpTHjHgVP6ObrQ?usp=sharing

3.1 Planning the Review

The goal of our study was specified according to the

GQM template (Solingen, 2002), shown in Figure 1.

Figure 1: Goal of the SLR according to GQM template.

For this review, we formulated the following

hypothesis and research questions (RQ).

Hypothesis 1: The development of model

transformations is a trend and different strategies

have been proposed in literature to support it.

However, there is still no well-defined strategy that

can be widely used by the community. We considered

as a well-defined strategy the proposal that: (i)

comprises the necessary elements, e.g. tasks and

artifacts, well organized to be followed as a guide,

such as development processes or tools; and (ii) is

stable enough, i.e. has been extensible tested, to be

widely used. This hypothesis motivated us to

construct the following research questions: RQ01:

What are the current strategies used to guide the

development of model transformations? In this

question, we want to identify the kinds of methods

that have been used in model transformation

development. RQ02: Which phases of software

development life cycle have been considered in

model transformations development? When

adopting a development strategy it is important to

consider the level of coverage of it concerning

software development life cycle, e.g. analysis, design,

implementation. RQ03: How automated is the

proposed strategy? Automation is an important

issue in any kind of software development because it

can promote better productivity as well as makes the

use of the approach easier. We are also interested in

strategies that generate the code of the MT. RQ04:

Which validated methods have been used to

evaluate the current proposals? We aim to evaluate

the feasibility of the approach, investigating how the

proposals were validated. RQ05: How many

examples of model transformations are tested in

each validation? We want to know if the strategy

was sufficiently tested to be considered stable for use.

Hypothesis 2: In MT specification, there is no

consensus on a notation to be adopted as a standard.

During a software development life cycle there are

some phases where the adoption of specific notations

is necessary, such as in software analysis and design.

Therefore, we wanted to map which modeling

languages have been used in each phase of

transformation development. This hypothesis led us

to construct the following research question. RQ06:

Which languages/notations have been used for

model transformations specification? The goal of

this research question is to identify if there is a

modeling language that could be considered a

standard for the model transformation domain.

To perform the review, we considered four

important research databases of Software

Engineering, ACM Digital Library, IEEE Library,

Science Direct and Springer where we selected works

using the following search string:

(MDE or MDD or MDA or Model Driven

Development) and (model transformation) and

(specification or development or approach or

strategy or framework or systematic or process

or methodology or method or life cycle)

This search string was applied to title, abstract and

key words. Besides the search string, we analyzed the

references of the selected papers and used the snow

balling method to find other relevant works.

Our research included works written in English

published between 2003 to 2019. The studies selected

from the automatic search were refined manually

according to the following inclusion/exclusion

criteria: Inclusion Criteria 1: the study identifies and

organizes the activities to develop MT. Rationale: the

focus of our research is on the strategies to guide

development; Exclusion Criteria 1: the study

presents a strategy to develop program

transformations. Rationale: program transformation

involves different activities and programming

languages from MT transformation; Exclusion

Criteria 2: the study focuses on non-relational

transformations. Rationale: these studies involve

other approaches of development (e.g. graph

transformations). We focus on relational-

transformation; Exclusion Criteria 3: the study is

about MT for a specific domain (e.g. transformations

for embedded systems). Rationale: These studies do

not focus on MT development, but support the

development of software in specific domains.

Exclusion Criteria 4: the study is about bidirectional

MT. Rationale: we focus on unidirectional MT. They

have different purposes. In order to evaluate the

quality of the selected articles we defined five quality

assessment criteria: Is there a proper introduction to

ICEIS 2020 - 22nd International Conference on Enterprise Information Systems

Table 1: Features defined to evaluate selected works.

Questions

Answers

What is the strategy used to guide development?

1 - development process 2 – tool

3 - systematic approach 4 - other (specify)

Does the study consider requirements specification

phase?

1 – no 2 - yes, informally described

3 - yes, described in detail 4 - not mentioned

Does the study consider design phase independent of

platform?

1 – no 2 - yes, informally described

3 - yes, described in detail 4 - not mentioned

Does the study provide instructions to map

requirements specification into design?

1 – no 2 - yes, but not automated

3 - yes, automated

Does the study consider design phase for specific

platform?

1 – no 2 - yes, informally described

3 - yes, described in detail 4 - not mentioned

Does the study provide instructions to map models

(design independent) into models (in specific platform)?

1 – no 2 - yes, but not automated

3 - yes, and automates it

Does the study consider implementation phase?

1 - no 2 – yes 3 - not mentioned

Does the study provide instructions for code generation

in specific languages?

1 - no 2 – yes 3 - not mentioned

Which are the methods used to validate/verify model

transformations?

1 - test case 2 - formal method

3 - other 4 - not mentioned

F10

Are validation/verification activities automated?

1 - no 2 – yes 3 - not mentioned

F11

Does the study use MDD approach?

1 - no 2 – yes

F12

Which are the modeling language adopted?

1 - natural language 2 - UML/light extension of UML

3 - heavy extension of UML 4 - proprietary notation

5 - formal language 6 - not mentioned

F13

Does the study provide a tool?

1 – no 2 - yes, proprietary

3 - yes, open source 4 - not mentioned

F14

What are the methods used to validate the proposal

feasibility?

1 – none 2 - example/proof of concept

3 - case study 4 - experiment

5 - other (specify)

the article? Does the introduction have a clear idea of

the research objectives? Is there a clear statement of

the results? Does it clearly describe the contributions?

Is the strategy validated? All the selected works fulfil

these criteria.

In order to help in the analysis of the articles we

defined certain features, based on the development

life cycle of model transformations (Table 1). The

first and second columns present, respectively, the Id

and a brief description of each feature. The third

column shows what was observed in the study in

order to analyze each feature and the last column

identifies the desired research question that we

wanted to answer with this feature. It is important to

highlight that some research questions may be related

to more than one feature.

4 CONDUCTING THE REVIEW

Table 2 shows the records returned according to each

research database.

The first column shows the research database, and

the others present the following results: number of

records identified after the search string application in

each database (column Initial); papers selected after

scanning titles (column Title); papers selected after

reading the abstract (column Abstract); papers

Table 2: Summary of the works.

Base

Initial

Title

Abstract

Introd

Final

ACM

270

IEEE

737

100

Science

Direct

343

Springer

995

Others

Total

2345

196

selected after reading the introduction (column

Introd); and papers whose full text was analyzed

(column Final). The row Others refers to the papers

added from other sources, after analyzing the

references of the previously selected papers.

5 REPORTING THE REVIEW

This section presents the results of the SLR. We used

R Software (RSoftware, 2019) to perform the

statistical analysis and generate graphics.

Figure 2 shows a timescale with the papers

selected after applying the inclusion / exclusion

criteria of our protocol. As can be seen, the number

of articles increased from 2003 until 2019. From 2005

(when the first paper was published) on, the number

of articles fluctuated until 2016 when an increasing

number of articles were published. This increase may

Developing Model Transformations: A Systematic Literature Review

indicate the community effort to establish effective

methods to aid the development of model

transformation. After that, we could perceive a

decrease in the number of works, which may indicate

that the proposals are becoming more stable.

Table 3 lists the Selected Papers (SP) in

chronological order with an id for each, their

publication year, title and the database where we

found them. These works were analyzed based on the

features defined in Table 1 in order to

confirm/refused the hypothesis formulated in Section

3, according to the research questions.

Figure 2: Distribution of articles along the years.

Concerning RQ01: What are the current

strategies used to guide the development of model

transformations? from the 23 studies considered

relevant we identified four different strategies to

guide MT development: (i) systematic approach,

which comprises a description of steps, written in

natural language, to be followed by developers; (ii)

algorithm, with steps described in natural language

and organized using control structures such as

conditionals and loops; (iii) software tools with an

embedded methodology to drive development; and

(iv) development process in a Process Modeling

Language (PML) with the relevant elements of a

process and their relationships (Figure 3).

As can be seen in Figure 3, systematic approaches are

the most commonly used strategy for MT

development (15 articles, 65%). In general, they were

the first initiatives in systematizing the tasks related

to MT development. Two works (9%) proposed

algorithms to organize the activities of development

in programming structures. Using these structures,

algorithms reduce the level of ambiguity that exists in

systematic approaches, although in these works they

were not implemented and had to be followed

manually. More recently, tools have been proposed (5

works, 22%) to improve MT development. In this

case, activities to support development are

encapsulated in proprietary environments. One work

proposes a development process, specified in a PML,

suitable for a MT domain.

Table 3: Selected Studies.

Year

Title

Search Base

SP1

2005

A systematic approach to design model transformation (Kuster, 2005)

IBM

SP2

2007

Towards Model Transformation Generation By-Example (Wimmer, 2007)

IEEE

SP3

2008

Transformation have to be developed ReST assured (Siikarla, 2008)

Springer

SP4

2009

Model Transformation by Demonstration (Sun, 2009)

Springer

SP5

2009

Towards the efficient development of model transformations using model weaving and

matching transformation (Del Fabro, 2009)

Springer

SP6

2010

Method of constructing model transformation rule based on reusable pattern (Li, 2010)

IEEE

SP7

2011

Model transformation specification for automated formal verification (Sani, 2011)

IEEE

SP8

2012

A model based development approach for model transformation (Kolahdouz-Rahimi, 2012)

ACM

SP9

2013

Engineering model transformation with transML (Guerra, 2013)

Springer

SP10

2013

Applying MDE to the (semi-) automatic development of model transformation (Bollati, 2013)

Science Direct

SP11

2013

The general algorithm for the MDA transfomation models (Tavac, 2013)

IEEE

SP12

2015

Specifying model transformation by direct manipulation using concrete visual notation and

interactive recommendation (Avazpour, 2015)

Science Direct

SP13

2016

Requirements engineering in model transformation development:a technique suitability

framework for Model Transformation Applications (Tehrani, 2016)

ACM

SP14

2016

Multi-Step learning and adaptative search for learning complex model transformations from

examples (Baki, 2016)

ACM

SP15

2016

Design pattern oriented development of model transformation (Ergin, 2016)

Science Direct

SP16

2016

Model-based M2M transformations based on drag-and-drop actions: Approach and

implementation (Skersys, 2016)

Science Direct

SP17

2016

A Model-Driven approach for model transformation (Ma, 2016)

IEEE

SP18

2016

Designing and describing QVTo model transformation (Tikhonova, 2016)

Scopus

SP19

2017

Formal concept analysis for specification of model transformation (Berranla, 2017)

IEEE

SP20

2018

EVL-Strace: a novel bidirectional model transformation approach (Semimi-Dehkordi, 2018)

Science Direct

SP21

2018

A generic approach to model generation operation (Kleiner, 2018)

Science Direct

SP22

2019

Model driven transformation development (MDTD): An approach for developing model to

model transformation (Magalhaes, 2019)

Sciene Direct

SP23

2019

Applying a Data-centric framework for Developing Model Transformations (Camargo, 2019)

ACM

ICEIS 2020 - 22nd International Conference on Enterprise Information Systems

Figure 3: Strategies to develop model transformations.

As well as the approach used in development, we

also identified the adoption of a wide number of

techniques to support development, such as

transformations by examples, transformation by

demonstration, weaving models, patterns, formal

methods, MDD, requirements engineering and

mathematical methods as illustrated in Figure 4.

Figure 4: Techniques used in transformation development.

Related to RQ02: Which phases of software

development life cycle have been considered for

model transformations development? Following

(Magalhaes, 2016) we considered that a MT

development life cycle comprises at least four phases:

Requirements, Design (and Design for a specific

platform), Implementation and Validation/

Verification. Figure 5 shows which of these phases

were considered in the papers analyzed. Features F2,

F3, F5, F7 and F9 were used to analyze data.

As shown in Figure 5, Requirements phase is

considered in 43% of the proposals (10 works), but

only 22% (not shown in the graph) of these works

detail how to perform the tasks. The others only

describe what might be specified. Most of the

proposals focus on Design, regardless of and/or

specific to a platform (78%) and Implementation

phases (18 works, 78%). The Validation/

Verification, a crucial phase for any software, is

considered in 39% (9 works). The method used in

Validation/ Verification (not showed in this article)

for those who considered this phase, 3% use test cases

(3 works), 56% (5 works) apply formal methods, and

11% (1 work) use other techniques. Moreover, 40%

of them (4 works) use automatic techniques to

perform validation.

Figure 5: Phases of model transformation development life

cycle.

To answer RQ03: How automated is the

proposed strategy? we analyzed the level of

automation between the phases of software

development life cycle (features F4, F6 and F8), for

example, supporting the map between requirements

specification and design phases and automation in

code generation. Four works provide automation

through modeling phases, while 13 works support

code generation. This shows that despite the change

in focus promoted by MDD from code to model,

transformation development still does not follow this

same direction. However, according to the percentage

of support for code generation, we can assume that

this scenario is beginning to change. The level of

abstraction is gradually increasing because some

years ago transformations used to be developed

manually directly in code.

Related to RQ04: What methods have been

used to validate the strategies? some methods have

been used to validate the selected proposals (feature

F14), according to Figure 6, 35% of the works (8

works) were validated using examples.

Figure 6: Validation methods used.

This method is important for obtaining initial results.

However, empirical methods are required nowadays

in order to provide more reliable results. We therefore

found an increase in the number of works using case

studies (26%, 6 works) and controlled experiments

(39%, 9 works), particularly in more recent works.

Related to the notations used in specification

stated in RQ06: What languages/notations have

been used in model transformations specification?

As shown in Figure 7 there are some options of

Developing Model Transformations: A Systematic Literature Review

notation available in literature. Two works (9%)

adopt UML or a lightweight extension of this (called

UML profiles). There are also two works (9%) that

use a heavyweight extension of UML. In this case,

UML semantics is modified making the use of

existing tools difficult. Thus, specific tools should be

used. Formal languages are still used in six works

(26%). Most works (10, which represent 43%)

propose new languages specific for transformation

domain (shown as a Proprietary language in the

graph). There is also one work that uses natural

languages. The others did not mention which

language was adopted.

Figure 7: Modeling languages.

Figure 8 synthesizes the results of our review

according to each RQ and the features used to answer

them in order to analyze the hypothesis.

Figure 8: Summarizing the selected studies.

For each research question, the figure shows the

related features and maps the articles (using its Id)

that provide the feature. For example, concerning the

strategy used to guide MT development (RQ01), the

first initiatives, called systematic approaches, were

proposed by SP1, SP2, SP3, SP4, SP7, SP8, SP9,

SP15, SP17, SP18, SP19 , SP21 and SP23. Other

works detail the necessary activities in steps

structured as algorithms (SP6 and SP11) or

encapsulate them in a tool (SP5, SP10, SP12, SP16,

SP20). The formalization of a process using PMLs

has recently been proposed, in SP22.

Summarizing these data, regarding hypothesis 1 -

The development of model transformations is a trend

and different strategies have been proposed in

literature to support it, but there is still no well-

defined strategy that can be widely used by the

community. We found four different strategies

presented in RQ1. However, we perceive that

although the number of works has been increasing,

they focus on specific aspects of development and do

not cover the entire life cycle (RQ2) and that

automation support also focuses on specific tasks,

usually in code generation (RQ3). There are

processes for the domain of model transformation

development, e.g. (Magalhaes, 2016), and tools, e.g.

(Bollati, 2013) and (Avazpour, 2015), however, we

perceive that they are not validated enough to be

widely used. As shown in RQ4, we observed the use

of different validation methods, but none of the

proposals have been exhaustively tested (RQ5). As a

result, we come to the conclusion that there is a lack

of a well-defined strategy, confirming hypothesis 1.

Finally, we come to the same conclusion for

hypothesis 2 - In model transformation specification,

there is no consensus on a notation to be adopted as a

standard, where in general, a proprietary language is

adopted in most works.

6 RELATED WORKS

Different strategies of software development have

been used to produce model transformations.

The survey presented in (Silva, 2015) discusses

the concepts that surround MDD, such as model,

metamodel and platform. Despite the importance of

this work for the community, its focus on the

definition of concepts, it does not discuss how to

develop transformations as we do in this paper.

Similar to our work, (Berranla, 2017) first

discusses the problem statement concerning MT

generation, i.e. proficiency in programming

languages and knowledge in metamodels. Then it

reports proposals to automate the development of

model transformations considering some dimensions,

such as the transformation inputs, outputs and

algorithm as the main elements to define a

development approach. The main difference between

our review and this is the viewpoint adopted to

classify the works as we use as reference the phases

of a software development life cycle. Moreover, we

also provide a quantitative result using graphics.

In (Bollati, 2013) the author carries out a SLR, the

main goal of which is to find proposals that use MDD

to develop model transformations. The review was

ICEIS 2020 - 22nd International Conference on Enterprise Information Systems

performed in five digital libraries and selected six

approaches. Compared to our literature review, she

includes works that use the MDA approach, from

PIM to code, while we cover any strategy related to

MT development life cycle. In addition, modeling

languages as well as methods used in proposal

validation are not mapped. Apart from these points,

the review dates from 2011 and there have been new

proposals since.

In the same direction as our work (Silva, 2014)

presents a literature review of MT development

approaches divided into three main groups: (a) MT

foundations, that identify which concepts of model

transformation are considered in each proposal (b)

features implemented in the approaches, e.g. which

phases of life cycle are considered; and (c) the

applicability of approaches. The review was

performed in the IEEE digital library and eight

approaches were selected. This review analyzes MT

foundations, which we do not. With regards to life

cycle, the review briefly defines some phases of

software development in order to evaluate the

proposals, e.g. modeling source and target

metamodels. In this, the concepts of phase and

activity are placed at the same level of abstraction,

which makes comparison with other works difficult.

In our review, in order to guide the analysis of the

proposals, we consider the main aspects of the life

cycle of software development processes presented in

the literature (Magalhaes, 2016), e.g. phases,

activities, and artifacts. Unlike (Silva, 2014), we also

explore the kind of modeling language adopted, e.g.

UML, proprietary and natural language, as well as

resources of automation. Furthermore, (Silva, 2014)

only use works in the IEEE database while we

consider four data sources.

In summary, we considered the review of (Bollati,

2013) included in our work, as we use a wider scope

in terms of goals and items analyzed in each proposal.

Moreover, we can say that the reviews of (Berranla,

2017) and (Silva, 2014) are complementary to our

work. The former uses a different viewpoint to

analyze the approaches and it interferes in the set of

selected works. In the second review, certain aspects

of MT foundations are analyzed that we did not take

into consideration. On the other hand, we analyzed

aspects such as automation and languages, which

were not covered in the work.

7 DISCUSSIONS

In this section, we discuss some of the issues

addressed in the selected papers and identify the

strengths and gaps in this research area.

It is well known that the quality of a product is

influenced by the process used to produce it

(Sommerville, 2011). Through our review we

observed an increasing number of proposals

concerning systematized methods in transformation

development. This might indicate that the community

is worried about improving transformation quality.

These proposals differ from each other in three

aspects mainly: (i) the level of specification

granularity; (ii) the level of formalism used in method

specification; and (iii) the coverage of phases

concerning to development life cycle.

According to (Sommerville, 2011), a software

development process must define what should be

done, how to perform it, when and by whom. Most

proposals analyzed focus on the definition of what

should be performed, i.e. identify and organize the

necessary tasks, but they do not detail how to perform

them. We perceived that this scenario is directly

related to the level of formalism used to specify the

proposed method. The first initiatives, e.g. (Kuster,

2005), (Wimmer, 2007), (Siikarla, 2008), (Sun,

2009), provide a description of the method in natural

language, what we call in our review a systematic

approach. Over the years proposals have become

more formal e.g. algorithms have been used to

structure the method, as in (Li, 2010) and in (Tavac,

2013), giving better support. Recently, some tools

have been proposed as in (Bollati, 2013) and in

(Avazpour, 2015) as well as a development process

specified in PMLs such as SPEM, e.g. (Magalhaes,

2019), providing resources for automation and

enactment that facilitate the adoption of the proposal

by others. Improving the strategies towards a well-

defined process is important to enable its replication.

Concerning the development life cycle, we

perceive that works usually focus on specific phases

but do not cover an entire life cycle. For example,

(Del Fabro, 2009) focus on design and

implementation, but do not support the requirements

specification phase, and (Sani, 2011) focus on formal

specification in order to enable transformation

verification. This feature may lead to the need to

adopt more than one method to cover all the

development. Consequently, problems, such as

selection of tools and document interchange, may

occur. Leaving the responsibility to solve this to the

Software Engineer may lead them to adopt ad-hoc

methods. Therefore, strategies should be specified to

Developing Model Transformations: A Systematic Literature Review

cover the entire development cycle of model

transformations.

The specification of transformations, as in other

software, requires the adoption of modeling

languages to produce the necessary documentation.

This is also essential for model refinement and code

generation. We found no consensus on the adoption

of a modeling language suitable for model

transformation development. As a result, different

proprietary modeling languages (and also UML

profiles and heavyweight extensions of UML) have

been used which may hamper communication and

interchange of documents between tools. QVT

(Query/View/Transformation), proposed by OMG as

a standard is in fact not widely adopted. As a result,

the definition of a modeling language which can be

used for both industry and academia, as there is in

programming languages (e.g. Java), is still required.

Finally, the development of model transformation

involves different elements, e.g. development

processes, modeling languages, modeling

environments, formal languages and automation, and

the current strategies usually do not cover all of these

aspects. Thus, developers have a hard job choosing

and integrating them. Therefore, integrated

approaches are also required in order to reduce the

complexity of the development.

8 THREATS TO VALIDITY

This section discusses some threats to the validity of

our review according to the guidelines of

wohlin(2012). Considering construction validity, to

decrease bias of the reviewers we established a

protocol for how the reviews should be conducted.

Related to internal validity, to reduce the chance of

relevant papers being excluded we defined features to

be observed in each study analyzed in our review.

Concerning external validity, we considered studies

in four major research databases however, we may

have missed some relevant studies. There is,

therefore, a threat to validity related to the

generalization of the conclusions of the study which

is minimized if we consider that the selected

databases contain the main publications in MDD.

Finally, in order to enable future replications of our

review, we used the Start tool. Thus all the

definitions, i.e. goal, research questions and the

protocol information, as well as the metadata of the

analyzed works in each stage, e.g. identification,

selection and extraction, are stored and can be used

by other researchers.

9 CONCLUSIONS

Over the last decade, many proposals have emerged

to reduce transformation development complexity as

well as improve transformation quality. Motivated by

the lack of consensus about which techniques and

methods are more appropriate, this paper presented a

SLR in an attempt to investigate the strategies

currently used in model transformation development.

This systematic review not only identified the

strategies most frequently used in transformation

development but also analyzed relevant issues to

support this development such as development

phases, modeling languages and the level of

automation provided.

Four strategies have been used to conduct

transformation development, systematic approaches,

algorithms, development processes, and tools. All of

them identify the main activities and organize them in

a structure to support development. In this direction,

different approaches to software development are

adopted, such as incremental and iterative process

model, MDD, transformation patterns or a

combination of these. Depending on the main goal,

specific phases of development life cycle are

considered. With regard to modeling languages, we

also found a wide range of proprietary languages

adopted in specification phases. Moreover,

automation techniques to improve productivity have

also been considered in more recent proposals.

In summary, we observed that much effort has

gone into reducing the level of complexity that

surrounds model transformation development.

Developers have been very busy experimenting,

however, there remains a lack of a stable strategy, one

which is well tested, i.e. in real scenarios, to be

replicated on a larger scale.

To conclude, it is well known that the definition

and validation of new development approaches,

which involve methods, languages and tools, are very

challenging and should be done gradually. We can

say that it has been almost fifteen years since MDD

was introduced in software construction, however,

transformation development practices are still in their

infancy. Defining an integrated approach, i.e. which

comprises method, languages and automation, that

covers the entire life cycle, and that is well-tested in

real scenarios remains a challenge. Understanding the

specificities of transformation development can

contribute to the widespread adoption of MDD.

ICEIS 2020 - 22nd International Conference on Enterprise Information Systems

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