TOWARDS A SUITE OF METRICS FOR BUSINESS PROCESS
MODELS IN BPMN
Elvira Rolón
Engineering Fac. “Arturo Narro Siller”, Autonomous University of Tamaulipas,
Centro Universitario Tampico-Madero, C.P. 89336 Tampico, Tams., México
Francisco Ruiz, Félix García, Mario Piattini
Department of Information Technologies and Systems , UCLM-Soluziona Research and Development Institute
University of Castilla-La Mancha, Paseo de la Universidad Nº 4, 13071 Ciudad Real, Spain
Keywords: Business Process, BPMN, Metrics, Conceptual Models, Software Process.
Abstract In this paper we present a suite of metrics for the evaluation of business process models using BPMN
notation. Our proposal is based on the FMESP framework, which was developed in order to integrate the
modeling and measurement of software processes. FMESP includes a set of metrics to provide the
quantitative basis necessary to know the maintainability of the software process models. This previously
existent proposal has been used in this work as the starting point to define a set of metrics for the evaluation
of the complexity of business process models defined with BPMN. To achieve this goal, the first step has
been to adopt the metrics of FMESP, which can be directly used to measure business process models, and
then, new metrics have been defined according to the particular aspects of the business processes and
BPMN notation.
1 INTRODUCTION
Software processes and business processes present
certain similarities. The most common is that both
try of capturing the main characteristics of a group
of partially ordered activities carried out to achieve a
specific goal, that they are those of obtaining a
product software (Acuña and Ferré, 2001) or a
satisfactory results (generally a product or service)
for the customer and other stakeholders of the
process respectively (Sharp and McDermott, 2000).
Curtis et al., (1992) define some of the specific
goals and benefits of modelling the software
process, such as: 1. Ease of understanding and
communication, 2. Process management support and
control, 3. Provision for automated orientations for
process performance, 4. Provision for automated
execution support, and 5. Process improvement
support.
On the other hand, some specific goals of
business process modelling are (Erickson and
Penker, 2000; Beck et al., 2005): 1. To ease the
understanding of the key mechanisms of an existing
business, 2. To serve as the basis for the creation of
appropriate information systems that support the
business, 3. To improve the current business
structure and operation, 4. To show the structure of
an innovated business, 5. To identify outsourcing
opportunities and, 6. To facilitate the alignment of
business specifications with the technical framework
that IT development needs.
Something that particularly characterizes
software and business processes is the fact that for
more than one decade and, as result of the
confrontation of the new technologies, more
competitive markets, business environments in
constant change and requirements for customer’s
satisfaction, the developers and software presidents,
as well as people of business and the organizations
in general have been focused in their processes like a
reference point to survive and prosper (Florac et al.,
1997). It has increased the necessity for analyzing,
evaluating, measuring and improving the processes.
As a result of the situation outlined above, the
modelling of business processes in particular is
440
Rolón E., Ruiz F., García F. and Piattini M. (2006).
TOWARDS A SUITE OF METRICS FOR BUSINESS PROCESS MODELS IN BPMN.
In Proceedings of the Eighth International Conference on Enterprise Information Systems - ISAS, pages 440-443
DOI: 10.5220/0002444304400443
Copyright
c
 SciTePress

becoming increasingly popular in the last years. In
this work, our target is to focus on the conceptual
level of the business process modelling, since we
believe that it is one of the point key to obtain
models of quality that can serve as support for an
effective maintainability and management of
business processes.
Conceptual process models show what a system
does or must do, they are independent of
implementation and the language to perform it is
usually a graphic language. This is the case of
Business Process Modeling Notation (BPMN)
(BPMI, 2004), which is the new standard for
modeling business processes and Web services
processes, proposed by the Business Process
Management Initiative (BPMI). In this paper, we
describe a proposal of metrics for business process
models represented in BPMN.
2 STARTING POINT
In our work we have based on the FMESP
(Framework for the Modeling and Evaluation of
Software Processes) proposal (García et al., 2006),
which consists of a framework for the modeling and
measurement of software process. FMESP is based
on the idea that it is necessary to carry out a good
administration of the software processes with the
purpose of obtaining software products with quality,
and such management considers it in an integrated
way by embracing two important aspects: the
process modeling and process evaluation. As a
result, it provides the conceptual and technological
support for the modeling and measurement of
software processes in order to promote their
improvement.
For the evaluation of the software process,
FMESP includes a set of metrics, which measures
the structural complexity of software processes
models (SPMs). The aim is to evaluate the influence
of the structural complexity of the software process
models on their maintainability. The FMESP metrics
have been defined by analysing the SPEM (Software
Process Engineering Metamodel) metamodel (OMG,
2002) at two different scopes and: model scope, to
evaluate the overall structural complexity of the
model and; core element scope, to evaluate the
concrete complexity of the fundamental elements of
the model, namely activities, roles and work
products.
With the aim to establish which metrics are
useful SPMs maintainability indicators, a family of
experiments was carried out (Canfora et al., 2005).
The FMESP metrics defined to evaluate the
complexity of concrete elements in the software
process model (activities, work products and process
roles) are not described here due to they are out of
the scope of this paper.
3 APPLICATION AND
EXTENSION OF FMESP TO
BPMN MODELS
The FMESP framework is based on the fact that the
research on software process measurement had been
focused on the study of the execution results and not
in the repercussion that could have the structural
complexity of the processes models in its quality. A
similar situation happens in the area of business
processes modelling. As a result of the research on
the side of business people, in the literature we can
find diverse proposals for the evaluation of
processes but mostly from the point of view of the
results obtained in their execution.
Considering our interest in evaluating the
business process by starting from the model that
represents it in a conceptual level, our work
recaptures the FMESP proposal but adapting and
extending it to business process models. To achieve
it we have defined a set of metrics to evaluate the
structural complexity of business process models in
a conceptual level.
The goal is to have empirical evidence about the
influence that the structural complexity of business
models can have on their maintainability. It can
provide companies with the quantitative basis
necessary to develop more maintainable business
process models. The first step to achieve this goal is
to define a set of suitable metrics for the evaluation
of the structural complexity of business models. This
definition has been based on the elements that
compose the BPMN metamodel. These metrics have
been grouped in two main categories: Base and
Derived Measures.
The base measures have been defined by
counting the different kind of elements that compose
a business process model represented with BPMN,
and 43 base measures have been defined according
to the main elements of BPMN metamodel. These
are distributed, in accordance with the four
categories of elements, in the following way: 37
base measures correspond with the Flow Objects
category, 2 with the Connecting Objects category, 2
with the Swimlanes category and 2 with the
Artefacts category. The first 37 base measures which
TOWARDS A SUITE OF METRICS FOR BUSINESS PROCESS MODELS IN BPMN
441

correspond with the Flow Objects category, are
grouped according to the common elements to which
they correspond. In this way, 23 measures have been
defined for the Event element, 9 for the Activity
element and 5 for the Gateways element.
With the base measures, it is possible to discover
how many significant elements there are in the
business process diagram. Nevertheless, starting
from the base measures a set of 14 derived measures
has been defined (Table 1) which allows us to see
the proportions that exist between the different
elements of the model. With all measures defined, it
is possible to evaluate the structural complexity of
business process models developed with BPMN. In
this way, when we structurally analyse the model, it
is also possible for us to evaluate its quality.
Table 1: Derived Measure based on BPMN.
Name
Definition
TNSE
Total Number of Start Events of the Model
TNSE = NSNE+NSTE+NSMsE+NSRE+
NSLE+NSMuE
TNIE
Total Number of Intermediate Events of the Model
TNIE = NINE+NITE+NIMsE+NIEE+NICaE+
NICoE+NIRE+NILE+NIMuE
TNEE
Total Number of End Events of the Model
TNEE = NENE+NEMsE+NEEE+NECaE+
NECoE+NELE+NEMuE+NETE
TNT
Total Number of Task of the Model
TNT = NT+NTL+NTMI+NTC
TNCS
Total Number of Collapsed Sub-Process of the Model
TNCS = NCS+NCSL+NCSMI+NCSC+NCSA
TNE
Total Number of Events of the Model
TNE = TNSE + TNIE + TNEE
TNG
Total Number of Gateways of the Model
TNG = NEDDB+NEDEB+NID+NCD+NPF
TNDO
Total Number of Data Objects in the Process Model
TNDO = NDOIn + NDOOut
CLA
Connectivity Level between Activities
CLA = TNT
NSF
CLP
Connectivity Level Between Pools
CLP = NMF
NP
PDOPIn
Proportion of Data Object like Incoming Product and
the total of Data Objects
PDOPIn = NDOIn
TNDO
PDOPOut
Proportion of Data Object like Outgoing Product and
the total of Data Objects
PDOPOut = NDOOut
TNDO
PDOTOut
Proportion of Data Object like Outgoing Product of
Activities of the Model
PDOTOut = NDOOut
TNT
PLT
Proportion of Pools and/or Lanes of the Process and
Activities in the Model
PLT = NL
TNT
We have described two proposals of metrics to
evaluate software process models and business
process models respectively. These metrics have
been defined on two different metamodels, namely
SPEM for software processes and BPMN for
business process models. It is important to highlight
that SPEM is a generic metamodel, and the measures
proposed can be applied to other process modelling
languages, even not specific to software as BPMN.
On the other hand, being BPMN specifically
focused on business processes it presents some
aspects that are not contemplated for software
processes and it means that new specific metrics are
necessary.
According to the issues mentioned, in order to
measure BPMN business process models the metrics
of the framework FMESP for SPEM have been
successfully applied, but new metrics (not defined in
FMESP) have been necessary due to the specific
notation of BPMN to model some particular aspects
of business processes. Table 2 shows the modelling
elements considered in SPEM and BPMN notations
.
Table 2: Elements of SPEM and BPMN for metrics
definition.
Element SPEM BPMN
Events
D
Activities
D D
Gateways
D
Work Products (Data Objects)
D D
Roles (Lanes)
D D
Dependences (Sequence Flow)
D D
Message Flow
D
Pools
D
As we can observe in Table 2, there are some
elements useful in BPMN for the modeling of
business process that SPEM does not contemplate,
such as the Events, Gateways, Message Flow and
Pools.
Since we have new base measures coming from
the use of the metamodel of BPMN, a new group of
derived measures is generated which has not been
defined in FMESP. With all the metrics defined, the
base ones as well as the derived ones, we believe
that one could have information about the structural
complexity of the model of business processes,
allowing us to evaluate aspects like their
understandability, coherence, completeness,
modifiability and consistency in order to assure the
quality of the model at conceptual level (Lindland et
al., 1994).
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4 CONCLUSIONS AND
FURTHER WORK
In this paper, we have displayed how the proposal of
FMESP can be applied in order to evaluate business
process models at conceptual level. Taking into
consideration that in the field of process engineering
there are not metrics applicable to business process
models at conceptual level, we make use of the
philosophy of FMESP in order to evaluate the
structural complexity of business process models.
We have taken as our starting point a definition of
base measures and derived measures following the
BPMN terminology, which is the most recent
standard notation defined by BPMI for the modeling
of business process.
By integrating both proposals, we provide a more
refined framework for evaluating business process
models. This gives support to Business Process
Management, which has as one of its stages the
definition and modelling of the process being
assessed. It will allow a more appropriate
management of the business processes and can
provide organizations with important profits.
Model metrics can be very useful to select the
models with the most easiness of maintenance
among various alternatives in companies with
change their models to improve their business
processes. Also, it can help to facilitate the business
processes evolution in these companies by assessing
the process improvement at conceptual level.
The business process model metrics provide
companies with objective information about the
maintainability of these models. More maintainable
models can benefit the management of the business
processes mainly in two ways: i) guaranteeing the
understanding and the diffusion of the processes, as
they evolve, without affecting their successful
execution; ii) reducing the effort necessary to change
the models with the consequent reduction of the
maintenance.
Currently we are developing a family of
experiments with the purpose of to evaluate quality
aspects of the conceptual business process models.
These experiments are been carried out with a
population integrated by experts in business analysis
and in software engineering in order to be able a
comparison between results of both kinds of
stakeholders and to determine the influence of these
different points of view.
Participants receive a kit consisting of a set of
business processes models represented with BPMN.
Models has different characteristics and dimensions.
A questionnaire is also provided for each one of the
models including questions related with its
understandability. In order to assess how influence
the BPMN notation in the modifiability of models
other additional section of the questionnaire asks
about several modifications -specially studied- to the
original model.
ACKNOWLEDGMENTS
This work has been partially financed by the
ENIGMAS Project (Junta de Comunidades de
Castilla-La Mancha, Consejería de Educación y
Ciencia, reference PBI-05-058) and MAS Project
(Ministerio de Ciencia y Tecnología, reference TIC
2003-02737-C02-02).
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