Refactoring Business Process Models

A Systematic Review

María Fernández-Ropero, Ricardo Pérez-Castillo and Mario Piattini

Instituto de Tecnologías y Sistemas de Información (ITSI), University of Castilla-La Mancha,

Paseo de la Universidad 4, 13071, Ciudad Real, Spain

Keywords: Refactoring, Business Process, Systematic Literature Review.

Abstract: Business processes are nowadays recognized as one of the intangible business assets that provide more

competitive advantage to organizations. Organizations must therefore be able to manage their business

process models and deal with their quality problems, i.e. lack of understandability, maintainability or

reusability among others. Such quality problems are exacerbated in business processes models that were

mined by reverse engineering from enterprise information systems, since business process are more likely to

undergo inconsistencies, redundancies, etc. Refactoring has proved to be a suitable solution to cope with

these quality problems. Refactoring changes the internal structure of a business process model while

preserves its external behaviour. This paper presents an in-depth systematic review for collecting,

categorizing and analyzing all the refactoring methods and techniques applied to business process models.

The systematic review is conducted following the formal methodology proposed by Kitchenhan. The review

reports 206 related studies, from which 16 were considered as primary studies. The most valuable

conclusion is that none of these studies proposes refactoring techniques for business process models

previously obtained by reverse engineering, which is considered as a greenfield research area.

1 INTRODUCTION

Business processes depict sequences of coordinated

business activities as well as the involved roles and

resources that organizations must carry out to

achieve common goals (Weske, 2007). Business

processes are today recognized as an intangible

business asset that provides competitive advantages

for organizations (Jeston et al., 2008). In addition,

most business processes are automated by enterprise

information systems.

To take an effective advantage of business

process management, business processes need to be

represented in models following standard notations

such as BPMN (Business Process Modeling and

Notation) (OMG, 2006). Organizations sometimes

do not explicitly have their business processes

models because they have never modeled their

business processes before. Even when the

organization has business process models, such

models can be outdated or misaligned regarding the

actual processes supported by enterprise information

systems. In these cases, reverse engineering

techniques can be used to obtain business process

models from existing information systems (Pérez-

Castillo et al., 2011a, Pérez-Castillo et al., 2011b).

This way, the retrieved models are prone to have a

lower quality degree since every reverse engineering

technique is characterized by a semantic loss when

the abstraction level is progressively increased (in

this case from existing information systems to

business processes).

In fact, bussiness process models can sometimes

present quality faults such as redundancies,

ambiguities, inconsistencies, lack of completeness,

as well as non-adherence to conventions or

standards, among others (Mens et al., 2007).

Business process models particularly obtained by

reverse engineering dramatically face these

problems. For this reason its is necessary to carry

out a refactoring process, which can solve the

mentioned quality problems. Refactoring modifies

the internal structure of business process models

without changing or altering the external semantics.

Refactoring techniques therefore make it possible to

improve the quality of business processes, so that

they become more understandable, maintenible and

reusable (Dijkman et al., 2011).

140

Fernández-Ropero M., Pérez-Castillo R. and Piattini M..

Refactoring Business Process Models - A Systematic Review.

DOI: 10.5220/0003993801400145

In Proceedings of the 7th International Conference on Evaluation of Novel Approaches to Software Engineering (ENASE-2012), pages 140-145

ISBN: 978-989-8565-13-6

 2012 SCITEPRESS (Science and Technology Publications, Lda.)

The concept of refactoring was proposed by

Opdyke in 1992 as a methodology for restructuring

programs (Opdyke, 1992). In the last decades

refactoring has emerged as a technique to improve

the maintainability of software systems. Traditional

refactoring primarily focuses on the level of source

code for the software life cycle, but it can also be

applied to the scope of the models (Mens and

Tourwé, 2004). For example, refactoring has been

applied to UML (Unified Modeling Language)

models and also to business process modeling.

Refactoring is also frequently termed as

restructuring since it is applied as the second stage

of software modernization process. Software

modernization advocates carrying out traditional

software reengineering following the model-driven

developments principles (i.e., considering all the

involved artifacts as models at different abstraction

levels). Software modernization consists of three

stages: (i) reverse engineering, which represents the

system at a higher level of abstraction; (ii)

restructuring or refactoring, which represents the

system at the same level of abstraction, improving

one or more properties of the system, preserving its

external behavior; and (iii) forward engineering,

which generates the implementation of the system at

a lower level of abstraction integrating the new

features included in the previous stage.

Business process models refactoring, within a

software modernization process, first needs to detect

refactoring opportunities and then it applies

refactoring operators. Currently, there are several

techniques and approaches to refactor business

process models. However, there is not a systematic

review of all available techniques in the literature in

order to understand its evolution and motivation in

each case. For this reason this paper presents a

systematic literature review to know the refactoring

techniques and detect those techniques that can be

particularly applied to business process models

retrieved by reverse engineering. The review

provides a summary of the state-of-the-art and

identifies possible areas of research that have not

been addressed yet.

The systematic literature review is planed and

conducted following the process proposed by

(Kitchenham and Charters, 2007) which is organized

in: (1) planning, which defines the research

questions and establishes the search protocol; (2)

execution, in which the search of research studies is

systematically carried out according to the protocol

defined in the previous phase; and (3) analysis of

results, in which some of the retrieved studies are

considered as primary and are analyzed to draw

conclusions.

After analyzing the studies retrieved during the

search, the following main conclusions were

obtained: (1) studies about business process

refactoring hardly ever provide an empirical

validation of their proposals, which reveals that this

research field is not mature enough; (2) there is an

increasing interest in the area in recent years; and (3)

none of the studies proposes to refactor business

process models previously obtained through reverse

engineering from existing information systems. As a

result, there is a potential research field that has not

been addressed by now.

The remaining of the paper is organized as

follows: Section 2 describes the first phase of the

systematic review through the formulation of

research questions. Section 3 corresponds to the

second phase of the systematic review, the

conduction. Section 4 describes the analysis of the

results, concluding the process of Kitchenham.

Finally, Section 5 shows the obtained conclusions

after the execution of a systematic literature review.

2 PLANNING THE REVIEW

This section presents the planning of the review. It

shows the research questions formulated and the

development of the protocol to guide the review.

2.1 Research Questions

This section provides the research questions

formulated in the review, which must be answered

after analysing the obtained results. Table 1 shows

the research questions RQ1 and the additional

question AQ1.

2.2 Development of the Protocol

This section specifies the method used to carry out

the systematic review. The review protocol provides

guidelines to find primary studies that give an

answer to the research questions. Thus, it is

necessary to have some selection criteria of these

primary studies for their inclusion in or exclusion

from the systematic review. Then, a categorization

of each primary study is performed through data

extraction.

2.2.1 Formulation of the Search Strings

In order to formulate the search string it is necessary

to know what to search and where to search.

RefactoringBusinessProcessModels-ASystematicReview

141

The answer to the first question is obtained from

search terms that are derived from the research

questions (‘Refactoring’ and ‘Business Process

Model’), together with the related terms that are

included in the search string by using the logical

OR. Some of these terms are subsets of other terms.

For this reason, it has been decided to select the

most general terms in order to avoid redundancies.

The search string is shown in Table 2.

As regards to where to search it is necessary to

establish a series of digital libraries where the

searches will be performed. The search of the string

mentioned above is performed in the following

digital libraries: (DL1) ACM Digital Library, (DL2)

Springer Link, (DL3) IEEE Xplore Digital Library

and (DL4) Scopus. Each of these digital libraries

provides a different search, so it is necessary to

make small changes in the search string in order to

adapt it to each of these mechanisms.

2.2.2 Selection Criteria

This section defines the inclusion and exclusion

criteria that must pass each of the studies retrieved

by the search string in order to be considered as

primary studies.

Inclusion criteria are those that determine if a

study is considered for review or not (see Table 3),

while exclusion criteria are applied after them to

exclude non-relevant studies (see Table 4).

2.2.3 Study Selection Procedure

The procedure to retrieve primary studies for the

systematic review is shown in Table 5.

3 CONDUCTING THE REVIEW

After planning the systematic literature review by

the search protocol the primary studies are obtained

by its execution. The steps for conducting the review

are:

1. Adapt the search string for each digital

library, since each one has different search

engines.

2. Carry out a search in each of the digital

libraries.

3. Apply de procedure of study selection to

obtain the primary studies.

4. Use the data extraction mechanism for

managing the relevant information from the

studies.

Table 1: Research Questions.

Id. Research Questions

RQ1 What techniques or procedures exist to carry

out refactoring business process models?

AQ1 Are there any techniques or procedures to

refactor business process models obtained

through reverse engineering?

Table 2: Research String.

Id. Research String

RS1 (Refactoring OR Restructuring OR Refactored

OR Refactor) AND (Process Model OR BPMN

OR Workflows OR Business Process)

Table 3: Inclusion Criteria.

Id. Inclusion Criteria

IC1 The study answers directly to the research

question

IC2 The study is focused on the refactoring of

business process models

IC3 The study has been published between January

2006 and December 2011

IC4 The study provides empirical validation

Table 4: Exclusion Criteria.

Id. Exclusion Criteria

EC1 The study has a business focus

EC2 The study has an approach away from software

engineering

EC3 The study is duplicated

EC4 The study is written in a language different to

English

EC5 The study shows only personal opinions or

anecdotes without scientific basis

Table 5: Procedure for studies selection.

1. Read Title and abstract of study e

2. Apply Inclusion Criteria (IC)

2.1. If ∀ c ∈ IC, e

SATISFIES c go to step 3

2.2. If ∃ c ∈ IC, e

¬SATISFIES c go to step 8

2.3. If not enough information to determine it, go

to step 3

3. Apply Exclusion Criteria (EC)

3.1. If ∀ c ∈ EC, e

¬SATISFIES c go to step 4

3.2. If ∃ c ∈ EC, e

SATISFIES c go to step 8

3.3. If not enough information to determine it, go

to step 4

4. Read full text

5. Apply Inclusion Criteria again (IC)

5.1. If ∀ c ∈ CI, e

SATISFIES c go to step 6

5.2. If ∃ c ∈ CI, e

¬SATISFIES c go to step 8

6. Apply Exclusion Criteria again (EC)

6.1. If ∃ c ∈ CE, e

SATISFIES c go to step 8

6.2. If ∀ c ∈ CE, e

¬SATISFIES c go to step 7

7. Accept study

8. Refuse study

ENASE2012-7thInternationalConferenceonEvaluationofNovelSoftwareApproachestoSoftwareEngineering

142

When applying the search protocol it is

necessary to extract the relevant information from

each retrieved study. To manage the information

from each of the studies it has been prepared a form

of relevant information that collects the relevant

information for each retrieved study as an identifier

of the study, the digital library where the study was

recovered, the title of the study, the list of authors of

the study and the year of publication of the study.

Also, the form includes information relating to the

satisfaction of the inclusion and exclusion criteria.

For each primary study, additional relevant

information is also stored for later analysis, i.e.

publication type (journal, conference or book), used

notation (BPMN, Petri Nets, PTS Tree or others)

and kind of empirical validation performed in the

study (experiment, study case, poll, example or no

validation). Moreover, the AQ1 (see Table 1) is

formulated to each of the primary studies. This

additional relevant information is collected to assess

the quality of each study.

All of the primary studies are indexed in the

database that provides the tool EndNote (Reuters,

2011). Additionally, all collected information during

the execution of the systematic review is available

online in (Pérez-Castillo and Fernández-Ropero,

2012).

4 ANALYSIS OF RESULTS

The obtained results are analyzed to be interpreted

and to draw conclusions. The systematic review was

carried out with two different analyses (see the

following sections): (1) a descriptive statistical

analysis and (2) a state-of-the-art assessment.

4.1 Statistics Analysis

After the execution of the search with the search

string 206 studies were retrieved and after full

execution of the review 16 studies were considered

as primary studies. Table 6 provides some

descriptive statistics.

Regarding the inclusion/exclusion criteria, only

7.77% of the studies met the inclusion and exclusion

criteria proposed at the beginning. In the case of the

ACM library only 28.57% of the studies were

accepted as primary studies, with 4 studies published

in journals, 9 published in conferences and 1

published in a book. In the case of Springer library

only 4.17% of studies were accepted, with 1

published in a book. This decrease is due to the fact

that most studies are duplicated in next libraries

because those studies met the exclusion criterion

EC3. The same happened with IEEE Xplore library;

for this reason none of studies were considered as

primary studies from this library. Finally, from

Scopus library only 0.96% of the retrieved studies

were considered as primary studies, with 1 published

in a journal, because it was the last library to search.

Concerning the kind of the publications, Table 6

shows that the majority of the studies (56%) have

been published in conferences while 31% and 13%

of the studies were respectively published in journals

or books. This indicates that the subject under study

does not have a great maturity degree.

Considering the year of publication, Figure 1

shows that there is a large increase of publications in

the last years. In fact, in 2010 there was an increase

in publication, but most of them are not relevant for

this review since they did not meet the inclusion

criteria (as answering the research questions) or

since those studies did not provide empirical

validation. Regarding primary studies, a growth is

observed along the years with various studies per

year from 2006.

Regarding the notation used to represent business

process in the primary studies, Petri Nets

predominates with 50% over all the primary studies

(see Figure 2 (a)). The next most predominant

notation is BPMN, which is used in 19% of the

primary studies. Petri Nets might be more

commonly used than BPMN given that Petri Nets is

a well-proven notation and it has been used since the

60’s while the BPMN notation is relatively new and

it is not widespread.

With respect to the type of the empirical

validation conducted in the primary studies, it shows

that most studies (63%) provide only examples (see

Figure 2 (b)). The reason for this could be a certain

lack of maturity in the field and only proposals have

been made.

Table 6: Summary of results.

Digital

Library

Retrieved

studies

Primary studies

Primary/

Retrieved

studies

Journal

Conference

Book

TOTAL

ACM 49 4 9 1 14 28.57%

Springer 24 0 0 1 1 4.17%

IEEE 29 0 0 0 0 0.00%

Scopus 104 1 0 0 1 0.96%

TOTAL 206 5 9 2 16 7.77%

Additionally, the analysis of the primary studies

revealed that no primary study considers business

process models obtained through reverse

engineering.

RefactoringBusinessProcessModels-ASystematicReview

143

Figure 1: Distribution of year of publication.

Figure 2: Distribution of primary studies according (a)

notation type and (b) empirical validation type.

Finally, the location of the authors involved in the

studies was also analyzed, since it may be important

to understand the usefulness of the findings. At least

ten countries were found, the most common of

which being Germany (5 authors) as well as China

and Switzerland (3 authors). Other countries as

Austria, Netherlands, United Kingdom and United

States have 2 authors, and Australia, Estonia and

Japan have one author.

4.2 State-of-the-Art Analysis

After analyzing the whole set of primary studies, a

set of common topics was collected. This analysis

establishes a relationship between the most common,

valuable topics and the primary studies addressing

such topics.

Table 7 shows the reference of each primary

study, that can be consulted in (Pérez-Castillo and

Fernández-Ropero, 2012), and also shows the digital

library where the study was retrieved and a list with

all the topics indicating which topic appears or is

addressed for each primary study.

There are 14 topics related to the studies. Topics

are related to whether the study shows some

scenarios (also called smells or refactoring

opportunities) where refactoring would be necessary

and, besides, if the algorithm used to make the

detection is shown. Moreover, topics related to

whether the study shows refactoring techniques and

its algorithm. Other topic is whether the study

proposes a metric. Furthermore, there are other

topics related to quality as readability, reusability,

Table 7: Topics of primary studies.

Reference of primary study

Digital Library

Detect refactoring

opportunities

Algorithms to detect

opportunities

Measuring and

Metrics

Refactoring

techniques

Refactoring

Algorithms

Business Process

Readability

Business Process

Understandability

Business Process

Maintainability

Violations or

Security

Business Process

Reusability

Implementation

(Tools)

Software Processes

or Workflow

PAIS

rocess-

Aware Information

System)

Process Variants

models

(Dijkman et al., 2011)

DL1 ♦ ♦

♦

♦ ♦ ♦

♦

(Dumas et al., 2011)

DL1

♦ ♦

♦

(Weber et al., 2011)

DL1 ♦

♦ ♦

♦

♦ ♦

(Zeng et al., 2010)

DL1 ♦ ♦

♦ ♦

(Hanakawa, 2011)

DL1

♦

(Leopold et al., 2010)

DL1 ♦ ♦

♦

♦ ♦

(Feineman, 2010)

DL4 ♦ ♦

♦ ♦

♦

(Weber and Reichert, 2008)

DL1 ♦

♦

♦ ♦

(Awad et al., 2009)

DL1 ♦

♦ ♦

♦

(Koehler et al., 2008)

DL1 ♦

♦

♦ ♦ ♦

♦

(Yan and Wang, 2009)

DL1 ♦

(Vanhatalo et al., 2008)

DL1 ♦

♦ ♦

♦

(Chivers and McDermid, 2006)

DL1

♦

(Wang et al., 2007)

DL1 ♦

♦

(Küster et al., 2006)

DL2 ♦

♦

(Singh et al., 2007)

DL1

♦

<2006 2006 2007 2008 2009 2010 2011

All studies Primary studies

19%

50%

25%

BPMN

Petri Nets

PTS Tree

Other

25%

12%

63%

Experiment

Study Case

Example

ENASE2012-7thInternationalConferenceonEvaluationofNovelSoftwareApproachestoSoftwareEngineering

144

security, understandability and maintainability. A

topic about whether the study proposes the

implementation of its algorithms or not. There is a

topic about whether the study is generic as software

process or workflow but it can be applied in this

context. Also, there is a topic on whether the study is

about PAIS (Process-Aware Information System).

Finally, there is a topic to indicate whether the study

makes refactoring of process variants models.

5 CONCLUSIONS

The paper presents a systematic literature review of

refactoring techniques and methods to be applied to

business process models obtained by reverse

engineering. The review has been carried out by

following the formal methodology proposed by

Kitchenham.

In total, 206 relevant studies were found in four

different digital libraries (ACM, SpringerLink, IEEE

Xplore and Scopus). 16 of these studies were

considered as primary according to the inclusion and

exclusion criteria and specific data were collected

from them in order to analyze them and to obtain

conclusions. After applying a statistical analysis the

most valuable findings were the following: (1) as

negative aspects: little empirical validation

performed. Most of the studies considered only an

example of the techniques or methods proposed, and

some were proposed as future work to validate their

proposals through study cases; (2) as beneficial

aspects: growing interest in the field due to

increased studies in recent years. It is also an area of

research which is not mature enough, so it is

interesting to address it.

Particularly, refactoring techniques have not

been especially developed to business processes

obtained by reverse engineering. Therefore, it may

be a possible field in which to make further research

efforts since it has not been addressed yet by the

research community.

ACKNOWLEDGEMENTS

This work was supported by the FPU Spanish

Program and the R&D projects ALTAMIRA (PII

2I09-0106-2463), PEGASO/MAGO (TIN2009-

13718-C02-01), MOTERO (JCCM and FEDER,

PEII11-0366-9449) and MEDUSAS (CDTI, IDI-

20090557).

REFERENCES

Dijkman, R., Gfeller, B., Küster, J. & Völzer, H. 2011.

Identifying refactoring opportunities in process model

repositories. Information and Software Technology.

Jeston, J., Nelis, J. & Davenport, T. 2008. Business

Process Management: Practical Guidelines to

Successful Implementations, NV, USA, Butterworth-

Heinemann (Elsevier Ltd.).

Kitchenham, B. & Charters, S. 2007. Guidelines for

performing systematic literature reviews in software

engineering. Engineering, 2.

Mens, T., Taentzer, G. & Müller, D. Year. Challenges in

model refactoring. In, 2007.

Mens, T. & Tourwé, T. 2004. A survey of software

refactoring. Software Engineering, IEEE Transactions

on, 30, 126-139.

Omg. 2006. Business Process Modeling Notation

Specification 1.0 [Online]. Available: http://www.

omg.org/bpmn/Documents/OMG_Final_Adopted_BP

MN_1-0_Spec_06-02-01.pdf [Accessed].

Opdyke, W. F. 1992. Refactoring: A program

restructuring aid in designing object-oriented

application frameworks. PhD thesis, University of

Illinois at Urbana-Champaign.

Pérez-Castillo, R. & Fernández-Ropero, M. 2012.

Refactoring Business Process Models - A Systematic

Review [Online]. Available: http://alarcos.esi.uclm.es/

per/rpdelcastillo/SLR.html [Accessed 21/02/2012

2012].

Pérez-Castillo, R., Fernández-Ropero, M., Guzmán, I. G.-

R. D. & Piattini, M. 2011a. MARBLE. A Business

Process Archeology Tool. 27th IEEE International

Conference on Software Maintenance (ICSM 2011).

Williamsburg, VI.

Pérez-Castillo, R., García-Rodríguez De Guzmán, I. &

Piattini, M. 2011b. Business Process Archeology using

MARBLE. Information and Software Technology.

Reuters, T. 2011. EndNote ®. Bibliographies Made Easy

™ http://www.endnote.com/.

Weske, M. 2007. Business Process Management:

Concepts, Languages, Architectures, Leipzig,

Alemania, Springer-Verlag Berlin Heidelberg.

RefactoringBusinessProcessModels-ASystematicReview

145