Applying and extending a semantic foundation for role-related concepts in enterprise modelling

Abstract

In this paper, we provide a semantic foundation for role-related concepts in Enterprise Modelling. We use a conceptual modelling framework to provide a well-founded underpinning for these concepts. We review a number of Enterprise Modelling approaches in light of the concepts described (namely, ARIS, Archimate, DoDAF, RM- ODP and BPMN). This allows us to understand the various approaches, to contrast them and to identify problems in their definition and/or usage. We start with a core set of concepts and then extend this set to address the social aspects of actors and roles in an organization. In particular, this enables us to investigate the actor-role relations in further detail.

Full text

Applying and Extending a Semantic Foundation for Role-Related
Concepts in Enterprise Modelling
João Paulo A. Almeida*, Giancarlo Guizzardi and Paulo S. Santos Jr.
Ontology and Conceptual Modelling Research Group (NEMO),
Computer Science Department, Federal University of Espírito Santo, Vitória, Brazil
(Received 20 February 2009; final version received 15 May 2009)
In this paper, we provide a semantic foundation for role-related concepts in Enterprise
Modelling. We use a conceptual modelling framework to provide a well-founded
underpinning for these concepts. We review a number of Enterprise Modelling
approaches in light of the concepts described (namely, ARIS, Archimate, DoDAF, RM-
ODP and BPMN). This allows us to understand the various approaches, to contrast them
and to identify problems in their definition and/or usage. We start with a core set of
concepts and then extend this set to address the social aspects of actors and roles in an
organization. In particular, this enables us to investigate the actor-role relations in further
detail.
Keywords: roles, actors, enterprise modelling, conceptual modelling, object modelling
1 Introduction
The concept of “role” is present in several Enterprise Modelling approaches [21, 26,
28, 33]. In most of these approaches, enterprise activities are performed by entities
which are called “actors”, “agents” or “objects” and that can be said to play “roles” in
these activities. Typically, the concept of role is used to define the responsibilities and
properties that apply to “actors” while playing “roles” and what actions (or kinds of
actions) are performed by which “actors”.
“Roles” are also highly relevant when discussing the actions that are
performed by users in interaction with a service or system and the service behaviour
with respect to user interaction. In this case, it becomes necessary to define the (kinds
of) actions that may be performed by particular (kinds of) users as well as the
representation of users‟ identities and their properties in the scope of the service or
system.
* Corresponding author: Email: jpalmeida@ieee.org

As discussed in [22] the role concept is based on a theatrical metaphor: “The
text of a play is expressed in terms of lines and actions associated with various roles,
which are declared initially in a cast-list. Putting the play on involves assigning actors
to the various roles, although one actor may play several minor roles, and the actor
playing a role may change during the run of the production. Identifying the roles
rather than the actors obviously makes the script more reusable.” Similarly, defining
an enterprise or service model in terms of “roles”, allows the model to remain stable
in the presence of dynamic changes in role playing.
Although the term “role” is significantly present in Enterprise Modelling
approaches, under close inspection, we can conclude that it often denotes different
underlying concepts with different basic properties. Given the importance of roles in
Enterprise Modelling, a clear semantic account for roles and role-related concepts is
necessary and would serve as a basis for communication, consensus and alignment of
the various approaches.
In this paper, we provide a semantic foundation for the role-related concepts in
Enterprise Architecture and Enterprise Modelling languages. Our claim is that some
theories of conceptual modelling (as consolidated in [13]) provide a well-founded
underpinning for these concepts, and allow us to harmonize competing proposals for
them.
We review a number of Enterprise Modelling approaches in light of the
proposed semantic foundation: Archimate, DoDAF, ARIS, BPMN and the RM-ODP
(Enterprise Viewpoint). This allows us to contrast the approaches and to identify the
problems in the definition, interpretation and/or usage of role-related concepts which
could lead to ambiguous and vague Enterprise Models. This is relevant from the
perspective of modellers who must select and manipulate modelling elements to

describe an Enterprise Architecture and from the perspective of stakeholders who will
be exposed to models for validation and decision making. In other words, a clear
semantic account of the concepts underlying Enterprise Modelling languages is
required for Enterprise Models to be used as a basis for the management, design and
evolution of an Enterprise Architecture. We start with a core set of concepts we have
introduced in previous work [2] and then in section 5, we extend this set to address
the social aspects of actors and roles in an organization. In particular, this enables us
to investigate the actor-role relations in further detail.
2 Features of the role concept
Steimann [31, 32] has identified a number of features for roles that appear throughout
the object-oriented and conceptual modelling literature (e.g., [9, 10, 11, 12, 13, 23, 24,
36]). We list each of those and introduce some examples to provide an intuitive notion
of the role concept, prior to its rigorous definition:
1) “A role comes with its own properties and behaviour.” For example, when
John is enrolled as a student at the University of Twente, he has a grade point
average (GPA), he can register to courses, receive grades, produce
assignments, take exams, etc. This feature seems to suggest that roles can be
regarded as a “type” characterizing a number of instances.
2) “Roles depend on relationships.” For example, the roles of husband and wife
as well as customer and supplier depend on the existence of a marriage or a
business relationship. This is confirmed by the usage of the concept of role in
the conceptual modelling literature as discussed in [13, 32] and as quoted in
[10]: “as suggested by the work of Sowa and Guarino, a role is meaningful

only in the context of a relationship.” This feature makes the concept of role
distinct from that of a phase or a state [32].
3) “An object may play different roles simultaneously.” For example, John can be
a student and a husband at the same time.
4) “An object may play the same role several times, simultaneously.” John can be
a student at the University of Twente and at the Tai Chi Institute
simultaneously.
5) “An object may acquire and abandon roles dynamically.” John is still a Person
after he graduates from the University of Twente.
6) “The sequence in which roles may be acquired and relinquished can be
subject to restrictions.” For example, John can only register in a graduate
school after he has completed an undergraduate course.
7) “Objects of unrelated types can play the same role.” For example, both a
person (John) and an organization (the University of Twente) can play the role
of customer in different business relationships.
8) “Roles can play roles.” For example, John can play the role of teaching
assistant for a particular course only if he is a student at the University of
Twente.
9) “A role can be transferred from one object to another.” For example, the
commitments and responsibilities of the role of president are transferred from
the incumbent president to his/her successor.
10) “The state of an object can be role-specific.” If John is a student at the
University of Twente and at the Tai Chi Institute simultaneously, John has a
GPA for each of those relations.

11) “Features of an object can be role-specific.” John attends all classes at this
undergraduate course at the University of Twente but at the same time misses
several classes in a row at the Tai Chi Institute.
12) “Roles restrict access.” We consider this an implementation-oriented feature,
considered by Steimann since he has surveyed object-oriented approaches in
general. Since we are concerned with conceptual models for enterprise
architectures, we do not include this feature further in our discussions.
13) “Different roles may share structure and behaviour.” For example, both
graduate students and undergraduate students have a student number, may
register to courses, etc.
Features 14 and 15 contradict each other, showing that there is lack of
agreement with respect to these features in the literature surveyed by Steimann:
14) “An object and its roles share identity.”
15) “An object and its roles have different identities.”
These features lead to the question of whether “John”, “John as a student of
the University of Twente”, “John as a student of the Tai Chi Institute” and “John as a
husband” are the same, or whether there should be different identities for each of the
roles John plays.
3 Role-related concepts in conceptual modelling
We proceed to identify a rigorous definition of the role concept, which requires some
preliminary definitions. We use an extract from a philosophically and cognitively
well-founded reference ontology (foundational ontology) that has been developed in
[13, 14].

First, we distinguish between conceptual entities called universals and
individuals [13]. The notion of universal underlies the most basic and widespread
constructs in conceptual modelling. Universals are predicative terms that can possibly
be applied to a multitude of individuals, capturing the general aspects of such
individuals. Individuals are entities that exist possessing a unique identity.
Figure 1 shows an extract of the foundational ontology adopted here (all
generalization relations depicted in this figure are disjoint, forming a simple “tree-
like” taxonomic structure for the entities considered in this model.)
Figure 1. Extract of the foundational ontology adopted here from [15]
This taxonomic structure reveals that an individual can be categorized as
substantial or moment [10]. A moment is an individual that existentially depends on
another individual, named its bearer. In the conceptual modelling literature, a moment
is said to inhere in its bearer. For example, the symptoms of a patient are said to
inhere in the patient, who bears the symptoms. In contrast, a substantial is an
individual that does not inhere in other individuals, i.e., which is not a moment.
Inherence is much stronger than a one-to-one relationship, since it implies existential
dependence between individuals. We have that an individual x is existentially
dependent on another individual y if, and only if, as a matter of necessity, y must exist

whenever x exists. (A moment may also inhere in another moment, the moments
forming a finite chain that ends with a substantial.)
In this paper, we characterize “actors”, “agents” or “objects” as substantials
and we explain the role-related notions in terms of moments. We use meta-properties
of universals (namely, existential dependence, external dependence and rigidity) to
clarify certain aspects of role-related concepts.
3.1 Qua individuals and relators
The taxonomic structure presented in Figure 1 reveals a kind of individual which is of
particular importance to the definition of role (in gray on the right side of the figure):
a “QuaIndividual”.
An example discussed in [15] clarifies this concept. Suppose that John is
married to Mary. John has a number of properties by virtue of being married to Mary.
For example, imagine all the legal responsibilities that John has in the context of this
relation. These newly acquired properties are moments of John that inheres in him
(and are hence existentially dependent on John). However, these moments also
depends on the existence of Mary. This type of moment is called externally dependent
moment. An externally dependent moment is an intrinsic moment (or quality) that
inheres in a single individual but that is existentially dependent on (possibly a
multitude of) other individuals external to its bearer (i.e., which is not the bearer‟s
parts or intrinsic moments). In the example, this other individual is Mary.
In the case of an externally dependent moment x there is always an event
which is the foundation of x. Again, in the given example, we can think of a certain
action a1 (the signing of a social contract) in which both John and Mary participate
and which founds the existence of the externally dependent moments inhering in
John. Now, we can define an individual that bears all externally dependent moments

of John that share the same external dependencies and the same foundation. This
individual is called a qua individual [23]. Qua individuals are, thus, a special type of
complex externally dependent qualities. In this case, the complex quality inhering in
John that bears all responsibilities that John acquires by virtue of the signing of a
social contract can be named John-qua-husband.
To continue with the same example, we can think about another qua individual
Mary-qua-wife which is a complex moment bearing all responsibilities that Mary
acquires by virtue of the same foundation and that albeit inhering in Mary are also
existentially dependent on John. The qua individuals John-qua-husband and Mary-
qua-wife are existentially dependent on each other. Now, we can define an aggregate
composed of these two qua individuals that share the same foundation. This aggregate
is called a relator.
3.2 Role universals
The taxonomic structure in Figure 1 also reveals a “Role” universal. A “Role”
universal applies contingently to an individual that bears (at least one) qua individual
of a certain type. In the example presented in the previous sub-section, we can say
that John is not only an instance of a “Person” universal but also an instance of a
“Husband” universal, while Mary is both an instance of a “Wife” universal. All
instances of a “Husband” universal exhibit the behaviour required of a husband in a
social contract (marriage).
At the same time John may play the role of student with respect to an
“Educational Institution” for example, the University of Twente. In this case, John
bears a qua individual John-qua-student, and is an instance of the “Student” universal
(John can register to courses, receive grades, produce assignments, take exams, etc.).

Further, John may also play the role of student with respect to other “Educational
Institutions”, for example, the Tai Chi Institute – bearing then qua individuals: John-
qua-student of the University of Twente and John-qua-student‟ of the Tai Chi
Institute.
We can say that roles universals can be restricted by certain allowed or
admissible types, i.e., certain universals to which a role universal can apply. For
example, in this case, we can say that the “Student” role can only be played by an
instance of the kind “Person”. A kind is the substantial universal which supplies a
principle of identity for its instances and that is instantiated necessarily by its
instances. Figure 2 shows a class diagram for this example, using the profile defined
in [13]. The characterization association represents that instances of
“PersonQuaStudent” inhere in an instance of “Student” (thus characterizing its
behaviour).
Figure 2. A role universal, its allowed type and a qua individual universal (from [13])
Figure 3 reveals the Enrolment relator universal (an instance of this universal
includes an instance of “PersonQuaStudent”). The relator universal reveals that both
an instance of “Student” and an instance of the “Education Institution” exhibit
particular properties (shared behaviour) in the relation. Please note that properties are
merely a dual way to represent behaviour.

Figure 3. A role universal, its allowed type and a relator universal (from [13])
3.3 Role mixin universals
The conceptualization in [13] also allows for a notion of role mixin universal which
captures commonalities in various role universals. This universal is used in a
conceptual modelling design pattern for “roles with multiple disjoint allowed types”
(see Figure 4). (We omit the description of role mixins from this paper, please see
[13] for a comprehensive discussion and characterization of a role mixin as an anti-
rigid non-sortal universal.) Intuitively, a role mixin universal allows us to add
flexibility to a role universal, without tying its definition to a specific kind. In the
example, it is possible to define a Customer independently of whether Persons or
Organizations play that role.
Figure 4. Modelling roles with multiple disjoint allowed types (an example from [13])
3.4 Examples

Table 1 summarizes the various examples presented throughout this paper and the
concepts they illustrate.
UFO-A
Example
role universal (a role universal
applies(contingently) to instances of
the role‟s allowed type.)
Husband; Wife; Student; PersonalCustomer;
CorporateCustomer.
role mixin universal (These universals
apply (contingently) to instances of
disjoint admissible types.)
Customer
instance of the role universal
(individual that bears a qua individual)
(instance of an admissible type for the
roles involved)
John;
Mary;
universals of the admissible types for
particular roles
Person (admissible type for roles Husband,
Wife, Student, Personal Customer);
Organization (for CorporateCustomer);
Customer (for CorporateCustomer and
PersonalCustomer);
qua individual (A qua individual is the
instance that characterizes the
individual with certain behaviour in the
context of a relation to another
individual.)
John-qua-husband; Mary-qua-wife; John-
qua-student (of the University of Twente);
John-qua-student‟ (of the Tai Chi Chuan
Institute).
qua individual universal
Person-qua-Student; Person-qua-Husband;
Person-qua-Wife.
the foundation of the qua individuals
(and hence the foundation of the
relator, i.e. a founding action or
behaviour.)
the signing of the social contract; the act of
enrolling at the university;
the act of enrolling at the Tai Chi Chuan
Institute.
relator (an aggregate of the qua
individuals in the relation.)
John and Mary‟s marriage; John‟s enrolment
at the University of Twente; John‟s
enrolment at the Tai Chi Chuan Institute.
relator universal
Marriage (this kind of social contract);
Enrolment (this kind of social contract).
individuals that are mediated by a
relator
John and Mary; John and the University of
Twente;
John and the Tai Chi Chuan Institute.
Table 1. Correspondence between role-related concepts in UFO-A and examples
3.5 Role-related concepts in the foundations and the features presented by
Steimann
We can consider the foundations with respect to each of the features of role-related
concepts as presented by Steimann:

1) “A role comes with its own properties and behaviour.” Yes, a qua individual
characterizes (with properties and behaviour) the substantials that play a
particular role.
2) “Roles depend on relationships.” Yes, a qua individual is externally
dependent.
3) “An object may play different roles simultaneously.” Yes, several qua
individuals may characterize the same substantial.
4) “An object may play the same role several times, simultaneously.” Yes, several
qua individuals that characterize a substantial may be instances of the same
universal.
5) “An object may acquire and abandon roles dynamically.” Yes, a role
universal applies contingently to substantials. In other words, a qua individual
describes a complex of contingent properties of individuals.
6) “The sequence in which roles may be acquired and relinquished can be subject
to restrictions.” Yes, one can define conditions for the foundation of relators.
7) “Objects of unrelated types can play the same role.” Yes, the mixin universal
can be used in the design pattern for “roles with multiple disjoint allowed
types”.
8) “Roles can play roles.” Yes, it is possible to restrict the admissible type of a
role to another role.
9) “A role can be transferred from one object to another.” Yes, this only requires
one to define rules for the foundations of relators.
10) “The state of an object can be role-specific.” Yes, see 1.
11) “Features of an object can be role-specific.” Yes, see 1.

13) “Different roles may share structure and behaviour.” Yes, a role universal
may specialize another role universal or role mixin universal.
With respect to contradicting 14 and 15 we can conclude:
14) “An object and its roles share identity.” Yes, if one considers that roles are
ultimately played by a substantial that carries a principle of identity.
15) “An object and its roles have different identities.” Yes, the qua individuals
have identities of their own.
4 Role-related concepts in Enterprise Modelling
In this section, we review role-related concepts in a number of enterprise modelling
approaches (Archimate, DoDAF, ARIS, BPMN and RM-ODP). We contrast the
definitions and usage of concepts in these approaches with the UFO-A
conceptualization described in section 3.
4.1 Archimate
In the Archimate Enterprise Architecture language [19, 21], the concepts of “business
actor” and “business role” are introduced. A business actor is defined as an active
entity that performs behaviour [21]. Examples of business actors include an individual
person, a department and a business unit. A business role is identified with the
purpose of making “the link between actors and behaviour more flexible.” A business
role is defined as that which “states which business behaviour is performed by a
business actor that fulfils this role.”
Intuitively, the definitions seem to imply that the business actor concept is a
substantial and that the business role concept is a role universal that may be applied
to actors (although the criteria of external dependency is not explicitly mentioned).

The language allows “actors” and “roles” to be related by what is called
“assignment”. Figure 5 shows an example of Archimate model with actors depicting
“actors” and “roles”. In this example, an “actor” named “Client” is assigned to the
“role” named “Insurance buyer”, which executes the behaviour “Buy insurance”.
Further, the actor “ArchiSurance” is assigned to the “role” named “Insurer”, which
executes the “Take out insurance” behaviour.
Although the definition for “actor” seems to imply that an “actor” is an
individual, the language makes no distinction between the “actor” as an individual
and a universal for “actors”. This can be observed in the example show in Figure 5.
The figure shows the “ArchiSurance” “actor” which denotes a particular insurance
company, i.e., it represents a particular substantial individual. Nevertheless, it also
shows a “Client” “actor” which is certainly not tied to a particular client (such as
“John”) (otherwise the business process itself would be client-specific.) We can
conclude that a “Client” in this case represents a universal for actual clients which
may participate in the business process. Based on this example, we can state that the
language lacks expressiveness with respect to the distinction between universals and
individuals when considering the “actor” concept. Thus, this lack of expressiveness
leads to a construct overload, which reduces the clarity of the language.

Figure 5. Archimate model (from [20])
4.1.1 Concept analysis: Interpretation A (Actors denote universals)
A feasible interpretation to enable our analysis is to consider all “actors” in Archimate
to denote universals, with certain “actors” representing universals that have only one
instance (and, hence, are singletons, such as “ArchiSurance” in the example presented
in Figure 5). Nevertheless, even with this interpretation, the language would not allow
one to identify which universals are singletons and which are not.
Under this interpretation, we consider that the “assignment” relation represents
a specialization/generalization relation between a role universal and its admissible
type. In this particular example, instances of “Client” are the individuals that can play
the role of “Insurance buyer”, i.e., that can instantiate the “Insurance buyer” universal.
4.1.2 Concept analysis: Interpretation B (Actors denote individuals)
An alternative interpretation would be to consider that the actor modelling element
indeed represents individuals and that Figure 5 represents an abuse in notation and
that in this case “Client” should be omitted from the model. This would be consistent

with the usage of the “actor” modelling element in several examples in the Archimate
documentation. See Figure 6 for an example of an Archimate model with a nesting of
actors, all of which are individuals (nesting of actors in Archimate implies either
aggregation or composition with no notational distinction possible).
Figure 6. Organization model (from [19])
Another example that corroborates this interpretation is presented in Figure 7. The
figure shows specific persons (“A. Smith”, “D. Jones”, and “M. Baker”) as “actors”
which are part of the departments of the insurance company.
Under interpretation B, we consider the assignment relation (shown in Figure
7) to show that the actor is an instance of the role universal represented by the role
modelling element. No statement is thus made about admissible types in general.

Figure 7. Organization model (from [19])
This interpretation would imply that Archimate cannot represent universals for
actors (the resemblance of Figure 7 with the UML Class Diagram notation is
unfortunate in this case, since the relations should be interpreted as links that relate
the whole to the part).
4.1.3 Generic relations
The Archimate language has a number of generic relations which can be applied
between a number of modelling elements. Nevertheless, the detailed semantics of
these relations when applied to particular kinds of concepts is not always clarified. A
particular example is the “specialization” relation.
The Archimate language reference manual [19] defines that “the specialization
relationship can relate any instance of a [modelling] concept with another instance of
the same concept.” The case of specialization of roles is mentioned explicitly (e.g.,
„junior‟ and „senior‟ specializations of the same role [20]), thus corroborating our
claim that roles are role universals. Nevertheless, the case of specialization of
“actors” is not mentioned explicitly. Specialization of “actors” would be acceptable
under interpretation A, but would be impossible under interpretation B (the
specialization relation is a relation between universals).

Other relations are “aggregation” and “composition”. These can be applied
between “actors” (as shown in Figure 6 and Figure 7), between “roles”, and also
between “actors” and “roles” (as shown in Figure 8.) Please note that from this model
it is impossible to derive the cardinality of the relation (i.e., should we interpret this
model as stating that there can be multiple “Damage experts” in a “Claim handling
department”?)
Figure 8. Relations between actors and roles [1]
Although examples of organigrams such as the one presented in Figure 9
appear in the Archimate Resource Tree [1] and in examples of tools such as
BizzDesign Architect [4], the semantics of the “relations” between “actors” is not
discussed in the Archimate language reference manual. Ideally, these “relations”
should be instances of material relations that are derived from relator universals.
Relator universals would define the particular attributions of each of the relata, and
their dynamics (creation and destruction) could be defined in the context of business
processes.
Figure 9. Example of Organigram [1]

4.2 DoDAF
The Department of Defense Architecture Framework (DoDAF) [33] defines two
products in the Operational View (OV) that include role-related concepts. These are
Operational Node Connectivity Description (OV-2) and Organizational Relationships
Chart (OV-4).
In OV-2, “An operational node is an element of the operational architecture
that produces, consumes, or processes information. What constitutes an operational
node can vary among architectures, including, but not limited to, representing an
operational/human role (e.g., Air Operations Commander), an organization (e.g.,
Office of the Secretary of Defense (OSD)) or organization type, i.e., a logical or
functional grouping (e.g., Logistics Node, Intelligence Node), and so on. The
operational node will also vary depending on the level of detail addressed by the
architecture effort.” [33]
In OV-4, “the Organizational Relationships Chart illustrates the command
structure or relationships among human roles, organizations, or organization types
that are the key players in an architecture.” [33]
The following definitions are provided for OV-4: “Human Role - Skills are
needed to perform the operational activities or business processes described in the
architecture”; “Organization - An administrative entity with a, identity, structure, and
mission.”; “Organization Type - A Class of Organization”; “Organizational
Relationship - relationships can include supervisory reporting, command and control
relationships, and command-subordinate relationships.”
Based on the definitions, we can, intuitively, interpret the “Human Role”
concept as a role universal with an implicit admissible universal to represent humans.

Further, we can interpret “Organization” as a substantial, and “Organization Type” as
a kind. There is no concept for kinds or substantials when applied to model humans.
DoDAF proposes a number of UML styles for representing an architecture,
including the aspects of the architecture that are related to roles and substantials.
Figure 10 shows the proposed UML style for OV-2. Similarly to Archimate, “roles”
are associated with the business processes in which they participate. Also, similarly to
Archimate, the structuring of “roles” in “nodes” with the “aggregation” relationship
suggests that nodes represent organizational units types in the context of which
substantials that play the roles operate. (It is unclear from the documentation whether
roles can be associated with multiple nodes directly.) We concluded that a “node”
represents a kind and that a “role” represents a role universal. The representation in
the lower part of Figure 10 confirms that by showing instances of “roles” and
“nodes”.
Figure 10. UML OV-2 template from [33]

Roles can be played by instances of other roles as can be seen in Figure 11. In
this case, we interpret the relations depicted as representing that the “Mission
Planner” “role” (a role universal) may apply to admissible type “Role 1”.
Figure 11. UML OV-4 Sample from [33]
The guidelines for UML usage in the DoDAF documentation are not
prescriptive enough, and hence, a number of tools, represent DoDAF architecture in
different styles. For example, MagicDraw provides a plug-in for DoDAF using its
own modelling elements. Figure 12 shows a screen shot of a model produced with this
plug-in.
Figure 12. DoDAF OV-4 Organizational Relationships Chart in MagicDraw [25]

In the IBM Rational Approach to the DoDAF [35], there is no semantics
associated with OV-4 diagrams. The document suggests the following with respect to
an organizational structure chart: “Create a Freeform diagram and name it
Organizational Structure. Add rectangles and label them for each organizational
element to be represented. Use vertical relationships via solid lines to reflect
command relationships, with higher authority at the top of the diagram. Show
coordinating relationships using dashed lines.”
The UML Profile for DoDAF/MODAF (UPDM) [27] defines an industry
standard UML representation for DoDAF and MODAF compliant enterprise
architectures. However, with respect to OV-4, the profile states that “this diagram
represents information generally developed and maintained using techniques and tools
better suited to the task than UML”.
4.3 RM-ODP
In our previous work [3], we have discussed the relation of the foundations presented
here and the RM-ODP foundations. We have concluded that the RM-ODP provides a
rich conceptualization when referring to the acts which constitute the foundation for
roles. In the Enterprise Viewpoint is possible to describe “enterprise objects” as
“communities” and detail their composition by using the concepts of “roles” and
constituent “objects”. We refer to [3] for further discussion on the topic.
4.4 BPMN
The Business Process Modelling Notation (BPMN) [26] focuses on business process
modelling, and therefore does not provide constructs for organization modelling.
Nevertheless, activities in a business process may be related by using the

“Participant” model element to either an “Entity” or a “Role”. Possible interpretations
for these concepts are kind and role universal or role mixin universal.
4.5 ARIS
The “Architecture of Integrated Information Systems” (ARIS) [28] framework is
widely employed for the description of enterprise architectures.
ARIS includes the following role-related concepts: “Organizational Unit”,
“Organizational Unit Type”, “Position”, “Employee” and “Role”.
The concept of “Organizational Unit” represents a substantial, instance of the
“Organizational Unit Type”, which we interpret as a kind. A “Position” is defined as
the smallest organizational unit possible (a particular job position). If we interpret this
definition literally, a “Position” represents an individual similarly to an organizational
unit. “Positions” can be related to “Organizational Units” to represent responsibility
(e.g., the CEO of IBM is “responsible for” the entire company) or to represent a
whole-part relation.
An “Employee” is a particular individual (an instance of a universal that is not
explicitly modelled.) A “Role” represents a role universal, all instances of which are
necessarily “Employees”, i.e., the only admissible type for “Roles” is the implicit
universal that characterizes all “Employees”.
The relation between “Roles” and “Positions” is rather indirect: when an
“Employee” is related to a “Position” (the foundation for this relation is the hiring
process), he/she plays the particular “Roles” that are somehow associated with the
“Position”.
Figure 13 shows an example of organigram in ARIS, illustrating the usage of
the concepts of “Organizational Unit”, “Positions”, “Employee” and “Role”.

Figure 13. Example of organigram [28]
“Organizational units”, “organizational unit types”, “positions”, “employees”
and “roles” can be related to a business process or its activities through an “executed
by” relation, as depicted in Figure 14.
The semantics of these concepts and relations are not clearly documented in
[28]. Thus, the analysis we have provided here must be considered as a first attempt to
establish a consistent interpretation of the constructs based on usage examples.
Figure 14 Example of process model with organization units and a position [28]
Sample
Co. Inc
Sales Billing Shipping
Secretary Sales Sales Manager Sales Clerk Billing Clerk 1 Billing Clerk 2 Shippi ng Clerk 1 Shipping Clerk 2
Pegi Stevies Troy Bennedit Tammy Carvielli Mike Beakley Tony Commide Amy Foster Lary Peadbody
Secretary Sales Clerk Billing Clerk Shipping Employee
Organization Unit
Position
Employee
Employee Type (Role)
Participante A
O...
.
executed by
is compared
with
Total
<= $12,000
Total
> $12,000
Customer
order arrived
Enter
customer order Sales
TotalTotal is compared
with
Register
order
executed by
Registered
Sales
manager

5 Role-related concepts in Enterprise Modelling using UFO-C
So far, we have employed a semantic foundation that applies to entities in general,
consolidating concepts from the conceptual and object-oriented modelling literature
that make no specific reference to the “social” aspects of these entities. In other
words, the concepts in this semantic foundation are neutral with respect to the social
aspects of entities and can be applied equally to refer to a building, a book, a person
and an organization such as a university.
Since organizations can be characterized as social individuals [6], further
specialization of this semantic foundation could help to clarify the social aspects of
actors and roles in an organization. In particular, we should observe that roles in the
scope of an organization are part of the social reality that is “constructed” because of
the acceptance of norms or rules in the scope of the organization [30]. This
observation helps us to clarify the relation between organizational units (actors) and
the roles that are played in the scope of organizational units. In the remaining of this
section, we briefly discuss a fragment of the extension of the UFO-A ontology called
UFO-C [16, 17]. This fragment introduces a specialization of concepts of UFO-A, to
include the concepts of agents, institutional agents, social objects, normative
descriptions, social roles and social relators. These concepts are depicted in Figure
15.
First of all, UFO-C differentiates the category of substantial individuals in
Agents and non-agents or Objects by employing the criterion that the former but not
the latter have the capability to bearing intentional moments. Intentional moments
have a type (e.g., Belief, Desire or Intention) and Propositional Content. For instance,
as an agent, John can hold the belief that “Mary is in love with him” and the desire of
being loved by Mary. In this case, we have that there are these two individual

moments which inhere in John (the individual belief and the individual desire) which
share the aforementioned propositional content. The propositional content of an
intention is named in UFO-C a Goal. For further details, please read [16, 17].
Figure 15 UFO-A fragment augmented with UFO-C extensions
The category of agents further specializes in physical agents (e.g., a person)
and social agents (e.g., an organization, a society). In an analogous manner, objects
can also be categorized as physical objects (e.g., cars, rocks and threes) or social
objects (e.g., a currency, a language, the Brazilian constitution). Agents can also be
further specialized into human agent, artificial agent and institutional agent, which
can be represented, respectively, by human beings, computationally-based agents and
organization or organizational unit (departments, areas and divisions). Institutional
agents are composed by a number of other agents, which can themselves be human
agents, artificial agents or other institutional agents.
We should now briefly elaborate on what is meant by stating that
“Institutional agents are composed of other agents”. An institutional agent
exemplifies what is named a functional complex in [13], i.e., a mereologically
complex entity whose parts play different roles with respect to the whole. By
instantiating each of these roles defined in the characterization of that functional

complex universal, each part contribute in a different way to the integral behaviour of
the whole. In the case of a social functional complex such as an institutional agent, the
characterization of the universal instantiated by that agent is made via what is termed
in the literature a normative description [6].
Each institutional agent has a normative description associated to it. Moreover,
this institutional agent defines a context in which a normative description is
recognized (see relationship recognized by in Figure 15). We can state then that
normative descriptions are social objects that create social entities recognized in that
context. Examples include social roles (e.g., president, manager, sales representative),
social agent universals (e.g., a political party, an education institution), social agents
(e.g., the Brazilian Labour Party, the University of Twente), social object universals
and other social objects (e.g., a piece of legislation, a currency) or other normative
descriptions. A normative description that defines social individuals in the context of
an institutional agent is termed a constitutive normative description [6].
The functional compositional structure of an institutional agent is hence
defined in the following manner. Let X be an institutional agent (or institutional agent
universal) and let N be a normative description associated to it. N defines for X a
number of functions that must be instantiated in order for X to exist, persist and
exemplify the essential properties (including behaviour) associated to (an instance of)
X. These functions are ascribed to a number of social roles prescribed to exist for X.
Finally, an agent z is a said to be a functional part of X (or an instance of X) iff z
instantiates one of the social roles defined in the normative description N associated
to X.
Besides defining social roles, normative descriptions can also define social
relator universals. As previously discussed, roles are relationally dependent

universals, i.e., roles are always defined in a context or in the scope of a relation.
Thus, in order for an individual (e.g., Mary) to instantiate a role (e.g., wife), she must
be mediated by a particular relator (e.g., the particular marriage between Mary and
John). The relator universal Marriage, in this case, characterizes the properties that
every instance of Wife (Husband) has in the context of that relation (or, equivalently,
while playing that role). Likewise, for an individual z to play a social role in the
structure of an institutional agent X, she must be mediated by an instance of a social
relator universal defined in the normative description N associated to X.
An example of a normative description type that defines social roles and social
relators is a social contract [7]. According to [7], social contracts describe tasks,
rules and specific obligations that are assigned to social roles that agents can assume
in an organization such as: interval in which an agent instantiates a social role; control
conditions, that is, how the organization is capable of governing an agent associated
to a role; consequences suffered by agents when norms are violated, among others. A
social contract is, hence, constituted by both deontic norms and technical norms [6].
Deontic norms prescribe and constrain the social behaviour of entities by defining
permission, obligations and rights associated to social roles. Technical norms regulate
the behaviour of individuals playing social roles inside an institutional agent by
prescribing the behaviour that should be exhibited by those individual when
performing actions associated to those social roles [6]. Finally, a social contract
provides a link between agents and social roles in the context of an organization, since
the signing of a contract constitutes a declarative speech act that serves as a
foundation for the creation of the social relator that binds the involved parts [29, 30].

5.1 Implications of the semantic extensions to Enterprise Modelling languages
In this section, we revisit the analysis of the role-related concepts of Archimate and
ARIS under the light of the UFO-C extensions presented in the previous section. We
focus on Archimate and ARIS for the sake of brevity.
5.1.1 Archimate
The first modelling element we revisit is Archimate‟s “Business Actor”. A “Business
Actor” represents an active entity that performs behaviour. In terms of the UFO-C
extensions, a “Business Actor” must be characterized as an agent (as opposed to an
object, which is non-agentive.) A distinction similar to that of agentive and non-
agentive entities is also present in Archimate, and is referred to using the terms
“active structure” and “passive structure”. Nevertheless, this distinction is not
formulated in terms of intentionality in action as in UFO-C.
When a “Business Actor” is used to represent an organization or
organizational unit, it should be interpreted as a special kind of agent, namely an
institutional agent. The relevance of this interpretation is that an Enterprise Modelling
language must be able to represent the decomposition of organizations and
organizational units into their various sub-organizational units and employees. If we
re-examine the model illustrated in Figure 7 (reproduced in Figure 16 below), we may
observe examples of institutional agents (“Insurance sales department” and “Claim
handling department”) and other agents that are not further decomposed (e.g., “A.
Smith”, “D. Jones” and “M. Baker”). Although Archimate does include notational
elements with different adornments to represent these different kinds of agents, their
usage is optional, and hence both organizational units and employees may be depicted
with the same notation, as in the model in Figure 16. This is a case of semantic

overloading and prevents us from incorporating a useful rule with respect to agents
such as “A. Smith”, “D. Jones” and “M. Baker”, namely that they cannot be involved
as a whole in a part-whole relation in the scope of the enterprise model.
Figure 16. Organization model (from [19])
The model in Figure 16 reveals a particular decomposition for the “Insurance
sales department” and the “Claim handling department” but omits the relations
between these institutional agents and the roles that would typically be captured in a
normative description that defines these departments. These relations are revealed in
the model of Figure 17, as a result of the omission of the “Business Actors” “A.
Smith”, “D. Jones” and “M. Baker”.
Figure 17. Relations between actors and roles [1]
Our first observation is that the diamond-adorned line is used in different ways
in Figures 16 and 17 leading to a case of semantic overloading of that syntactical
construct. In Figure 16, these lines represent a whole-part relation between agents (we

assume here all at the instance level). In contrast, in Figure 17, these lines represent a
relation between “Business Actors” and “Business Roles”.
This latter relation deserves further attention, since it collapses several notions
which are required to relate institutional agents, social roles and the agents that
perform them. There are multiple possible interpretations to the model in Figure 17:
In the first alternative interpretation, which is suggested by the comparison of
Figures 16 and 17, each role “Sales representative”, “Financial expert” and “Damage
expert” represent in fact an anonymous instance of the role (an agent) and not the role
universal. The number of agents is defined here to be three.
In the second alternative interpretation, the “Business Role” modelling
element is a genuine universal and the institutional agents “Insurance sales
department” and “Claim handling department” consist of a number of agents that
perform the roles of “Sales representative”, “Financial expert” and “Damage expert”.
(As noted earlier, the number of agents is undetermined in this model.)
It is important to highlight that, judging by most of the available examples
using the Archimate notation, the second interpretation seems to be intended one.
However, as a consequence of the aforementioned semantic overloading as well as the
lack of precision in the definition of the real-world semantics of the semantic
primitives of this notation, both interpretations can be elicited when construing
Archimate models. We can conclude a revision of these modelling elements is
necessary in order to establish a precise and useful semantics for the actor-role
relation in Archimate.
Further, since the concept of normative description remains implicit in the
models, we can either assume that (i) the roles “Sales representative”, “Financial
expert” and “Damage expert” are defined in the scope of the organization as a whole

(perhaps in a normative description that defines the organization as a whole) or that
(ii) these roles are created in the normative description that defines the institutional
agents “Insurance sales department” and “Claim handling department”. In the latter
case, these roles may be specific to the organizational units in question, and may be
useful to determine specific attributions in the scope of that organizational unit (e.g.,
there could be “Car insurance sales representative” and “Home insurance sales
representative” roles in the “Insurance sales department”). There are no modelling
elements currently in Archimate to provide this distinction. This distinction seems
particularly important when modelling large bodies of organization with several levels
of hierarchies and rules, such as a government body or a community in federation.
5.1.2 ARIS
The concepts introduced in the UFO-C extension also enable us to revisit the
interpretation for the “Organizational Unit” and “Position” modelling elements in
ARIS.
First, we are able to refine the interpretation of the “Organizational Unit”
modelling element, concluding that it represents a particular kind of substantial,
namely, an institutional agent. This is not particularly surprising given that
organizational units can be decomposed recursively into smaller organizational units
and eventually into “Positions”.
If we follow the ARIS definition literally, i.e., if we accept that “a position is
the smallest organizational unit” as we have done in section 4.5, we may be tempted
to suggest that a “Position” should be interpreted as an institutional agent. However, a
“Position” cannot be further decomposed, and it would thus be interpreted as an
institutional agent with a single constituting agent. This would violate the weak
supplementation principle [13]. In other words, why should one distinguish the

institutional agent that corresponds to the “Position” from the actual agent in that
“Position”? Secondly, and perhaps more importantly, this allegedly characteristics of
“Positions” would make it of an intrinsically different nature than other organizational
units. Moreover, even if “Positions” are to be accepted as an uncanny type of
organizational unit, one still could not dispense with position universals. Take for
example, the model reproduced in Figure 18. There we have that the Billing
department “has” a “Billing Clerk 1” and a “Billing Clerk 2”. Still in this example,
there is implicitly the universal “Billing Clerk” which defines properties which are
common to these two “Positions”. Now, what is the difference between a social role
“Billing Clerk” and the position universal “Billing Clerk”?
Intuitively, one could assume this is necessary to decouple organizational units
and employees, however, the same effect can be obtained with the roles employees
perform in an organizational unit. This suggests that the existence of both “Positions”
and “Roles” is a violation of parsimony in ARIS and that “Positions” can be safely be
replaced by roles to be performed in the scope of a particular organizational unit.
The implications for the example discussed earlier (and reproduced in Figure
18) are that the “Positions” identified here would be specializations of the “Roles”
which are allowed types for the agents filling these “Positions” (these specialization
relations are not modelled here). The relations between “Employees” and “Positions”
and between “Employees” and “Roles” are in this case, instantiation relations.
Further, the existence of multiple “Positions” with similar designations such as
“Shipping Clerk 1” and “Shipping Clerk 2” may suggest that these are in fact just
cardinality restrictions for the instantiation of an implicit role “Shipping Clerk”.
However, depending on the intention of the modeller, this could actually mean that
there are different attributions to “Shipping Clerk 1” and “Shipping Clerk 2”, in which

case these would just be two different roles (universals) that do not share all
properties. Still in this case, we could have that the social roles “Billing Clerk 1” and
“Billing Clerk 2” could be specializations of the social role “Billing Clerk”. The
relation between “Organizational Units” and “Positions” is similar to that discussed
for the relation between “Business Actors” and “Business Roles” in the Archimate
insurance example.
Figure 18. Example of organigram [28]
At first investigation it seems that the relation between the “Organizational
Unit” and “Position” modelling elements would indicate that the role specified by a
“Position” is defined in a normative description that is recognized only in the scope of
the containing “Organizational Unit”. However, the relation between “Sales
Manager” and “Billing” suggests otherwise. Therefore, we conclude that, similarly to
Archimate, the relation between the “Organizational Unit” and the “Position”
modelling elements does not indicate the context in which the roles are defined.
Sample
Co. Inc
Sales Billing Shipping
Secretary Sales Sales Manager Sales Clerk Billing Clerk 1 Billing Clerk 2 Shippi ng Clerk 1 Shipping Clerk 2
Pegi Stevies Troy Bennedit Tammy Carvielli Mike Beakley Tony Commide Amy Foster Lary Peadbody
Secretary Sales Clerk Billing Clerk Shipping Employee
Organization Unit
Position
Employee
Employee Type (Role)

6 Conclusions
We have contributed a semantic foundation for role-related concepts in Enterprise
Modelling. Our contribution is well-positioned with respect to the literature in
conceptual and object-oriented modelling †, thus possibly leading to a common
foundation for these modelling domains. The semantic foundation also incorporates
social concepts in line with approaches in enterprise modelling and enterprise
ontology, such as [5, 6, 8].
We have found a number of difficulties in evaluating the selected enterprise
modelling approaches, which reveals certain problems in the definition and
potentially in the usage of some modelling elements in these approaches:
In the case of Archimate, the main difficulties refer to the interpretation of the
concept of “actor”. It was unclear from the documentation and from examples,
whether the concept should be interpreted as a universal or an individual. We believe
both universals and individuals for actors are relevant in enterprise modelling efforts
(see section 5). Further, we have identified a number of issues in expressing the
relations between actors and roles in the approach. Future work should focus on
language revision and specific modelling guidelines to ensure the language can be
given a precise semantics for this relation.
In the case of DoDAF, most issues relate to a lack of consensus on the
language representation for the concepts, which restricts our analysis to the concepts
as defined in the framework. We have concluded based on our analysis that there is no
concept for kind or substantials when applied to model humans in DoDAF. This
would make it impossible to model the interest in particular individuals (such as the
† For an extensive discussion on roles in the conceptual modelling literature that justify the UFO-A
conceptualization see [13, 15]. In [13, 15] the conceptualization provided here is defined formally, in order to
allow for unambiguous interpretation of the intended semantics for concepts.

allocation or deployment of persons to particular organizational units, as shown in
Archimate and ARIS).
In the case of ARIS, both universals and individuals are provided for
modelling organizational units. Individual human actors are also represented. The
ARIS documentation has been hard to interpret (especially the role-related concepts
as presented in [28]). Therefore, the semantics of the various modelling elements has
been derived based on its usage in examples. We have proposed a revision of the
ARIS "Position" concept unifying it with the notion of role. This leads to a more
parsimonious set of role-related concepts in ARIS and, ultimately, more parsimonious
models.
In none of the approaches, we could identify the distinction between the
concepts of role universals and role mixin universals. In order to be able to model the
design pattern for “roles with multiple disjoint allowed types” (which is one of the
challenges presented in [32]), the approaches would have to collapse both concepts of
role universals and role mixin universals in a single concept.
In all approaches, roles are used to represent the participation of actors in
particular behaviours or processes, decoupling the definition of these behaviour or
processes from particular instances of actors. None of the approaches, however,
discuss the dynamics of role playing or provide modelling elements to describe how
actors are assigned to roles dynamically (except the RM-ODP). The concept of qua-
individual is very important in this respect and necessary to enable features 1, 9, 10
and 11 of the list proposed by Steimann, i.e., those related to the properties and
behaviour that individuals carry when playing a certain role. Qua individuals are also
necessary to clarify the issue of identity and to solve the so-called “counting problem”
[15].

Further, in all approaches, the concept of normative description remains
implicit in the models, thus, the scope of social roles is left unspecified. We believe
that modelling the scope of social roles could be particularly beneficial for modelling
large bodies of organization with several levels of hierarchy and federation.
Further work is needed to discuss the the metaproperties of whole part
relations for role-related concepts in details. Some discussions on this topic can be
found in [13]. Further, some work is needed to relate the concepts discussed here to
social concepts which are also available in enterprise modelling approaches such as
commitments, delegation, contracts, goals, etc. [5, 6, 8,16].
Acknowledgements
This work has been supported by CNPq (Brazilian National Council for Scientific and
Technological Development), FAPES (Fundação de Apoio à Ciência e Tecnologia do
Espírito Santo) in the context of the INFRA-MODELA project, and FACITEC
(Fundo de Apoio à Ciência e Tecnologia do Município de Vitória) in the scope of the
MODELA project.
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