An ontology-based approach to role-human assignment in human processes for knowledge intensive services

Expert Systems with Applications 38 (2011) 8352–8369

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Expert Systems with Applications journal homepage: www.elsevier.com/locate/eswa

An ontology-based approach to role-human assignment in human processes for knowledge intensive services Wonchul Seo a, Sungchul Choi a, Kwangsoo Kim a,⇑, Jae Yeol Lee b a b

Department of Industrial and Management Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Kyungbuk 790-784, Republic of Korea Department of Industrial Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, Republic of Korea

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Keywords: Role-human assignment Knowledge intensive service Role-based process modeling Human process management Ontological engineering Topic Maps

a b s t r a c t Knowledge intensive service processes should be managed in a human-oriented way since human workers who naturally undertake complex operations of an intellectual nature in the processes are the most valuable resources for service-providing companies. For the human-oriented management, a role-based approach has been widely applied. The foremost step in the role-based human process management is to assign relevant roles to appropriate humans. The role assignment task is also highly dependent on the ability of humans to consider information about roles and humans. In order to manage the role assignment in a human-oriented way, this paper presents two fundamental principles upon which the assignment task is carried out. First, roles should not be assigned until they need to be activated; second, the authority for the role assignment should be distributed to participants in the processes. In order to support the principles, the information should be explicitly and formally described to enable all the participants to easily understand and utilize it. Consequently, this paper proposes a methodology for managing the role assignment in a human-oriented way by adopting an ontological approach which can precisely describe the information. From the proposed methodology, human workers can be notified which roles are triggered to be activated and wait to be assigned. Moreover, they can be provided appropriate candidate humans when carrying out the assignment task. The contribution of this paper is to suggest a role assignment methodology that not only lightens the assignment workload by providing the capability of identifying a small set of appropriate candidates but also enables the efficient assignment by streamlining the assignment task. Ó 2011 Elsevier Ltd. All rights reserved.

1. Introduction Knowledge intensive service activities provide an opportunity for companies to increase competitiveness and accelerate innovation by bringing valuable external knowledge to them. A knowledge intensive service is a specialized business service that aims to create value-added activities and customized solutions to meet client’s needs by relying heavily on knowledge works (Bettencourt, Ostrom, Brown, & Roundtree, 2002; Miles, Kastrinos, Flanagan, Bilderbeek, & den Hertog, 1995; Toivonen, 2006). As the knowledge work is high level professional work which contributes to the satisfaction of clients’ needs, knowledge workers are the most valuable resources for service-providing companies (Liebowitz, 2001). The workers generally undertake complex operations of an intellectual nature to develop and deliver the services (Alvesson, 1995; Miles, 2005; Muller & Doloreux, 2009). Therefore, systematical management of complex service processes is the most ⇑ Corresponding author. Tel.: +82 54 279 2195; fax: +82 54 279 5998. E-mail addresses: [email protected] (W. Seo), [email protected] (S. Choi), [email protected] (K. Kim), [email protected] (J.Y. Lee). 0957-4174/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.eswa.2011.01.024

important objective that the service-providing companies have. Traditional Business Process Management (BPM) methodologies and solutions have been applied for this purpose as they have allowed the service-providing companies to deal with a wide range of the process management. However, most of the concerns that they take care of are mechanistic system-to-system scenarios with pre-defined workflows. The way humans work in complex service processes is not quite the same as the way mechanistic systems do, since the systems simply follow a pre-defined sequence of activities one after the other. Humans inherently do what they like and what they think necessary (Harrison-Broninski, 2008). Consequently, it is necessary to develop a way to manage the service processes in a human-oriented way. A radical new business theory of Human Interaction Management (HIM) has been suggested to support modeling and managing human processes (Harrison-Broninski, 2005). In order to deal with the human processes, HIM lays a role concept at its heart since the role concept is generally regarded to be compatible with general human work behavior. There are many different role concepts applied in different systems (Zhu, 2006; Zhu & Zhou, 2008). Among them, roles highly relevant to human collaborative systems

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are discussed in HIM. In this respect, a role can be defined as a set of prescriptions describing how people should behave with responsibilities required to carry out specific activities (Ashforth, 2001; Bostrom, 1980; King & Sethi, 1998). Thus, through clearly defined roles in human processes, humans can be well informed about what objects they can access with specific rights and which people they can manage or communicate with, and ultimately they can be facilitated in accomplishing their jobs meaningfully and efficiently (Zhu & Zhou, 2006). The first step to enact the role-based human processes is to assign relevant roles to appropriate humans. However, current HIM methods do not sufficiently address the assignment issue. Most research on the role assignment focus on how to automate the assignment task based on trustworthiness judgments since they attempt to control access permissions of users on the resources in open distributed systems. The automation approaches seem appropriate in such systems where user population is dynamic and the identity of users is unknown (Saffarian, Tang, Jonker, & Hartel, 2009). However, the situation becomes different in knowledge intensive service processes since human workers are generally reliable and their information is totally managed in the service-providing company. In such a situation, the focus of the assignment issue should move towards formalizing the information about roles and humans. For example, failure to consider the capabilities or skills of human workers raises the risk of requesting that they carry out activities that are beyond their capabilities. Therefore, an assignor needs to carefully consider the formalized information in order to assign roles to appropriate humans in service processes. In this respect, the role assignment mandates that people should strongly intervene in the assignment task by considering the information. Although the automation in the assignment is not the most important thing since the assignment task is intrinsically human-oriented, the computerized support must be of great value. This is because it can provide various useful ways to modeling and managing the formalized information. Hence, this paper focuses on how to facilitate the role assignment task, mostly driven by humans, by providing a concrete methodology and computerized support. This paper aims to present a methodology for facilitating the role assignment, which is central to an enactment of human processes for knowledge intensive services. In order to assign roles to appropriate humans, diverse information about roles and humans should be considered, such as what the goal of the role is, what capabilities are provided by humans and so on. Therefore, this paper adopts an ontological approach to explicitly and formally describing the information about roles and humans. As an ontology is a formal explicit specification of a shared conceptualization (Borst, 1997; Gruber, 1993), ontologies are widely used for specifying any shared knowledge in a well-defined and unambiguous way (Guarino, 1998). Thus, through the ontological approach, one can precisely describe roles and humans, and subsequently make formal relationships between the two. Among the many factors in selecting appropriate humans, we focus on the following fundamental aspects of roles and humans: (1) goals to be achieved by roles and responsibilities required to carry out activities in roles and (2) experience of humans in terms of a set of roles which they had played and a set of capabilities they possess. The purpose of this paper is to present a methodology for identifying appropriate candidates for a certain role based on the fundamental factors which are formally described. The rest of this paper is organized as follows. Section 2 reviews related works. Section 3 discusses fundamental principles of the role assignment and Section 4 presents an overall procedure for the role assignment methodology. Section 5 presents ontological specifications of roles and humans. Section 6 presents a procedure for creating new roles and relating them to existing ones in the role

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and human ontologies. Section 7 provides a way to identify candidate humans for a certain role using the ontological specifications. Section 8 presents a prototype implementation. Finally, Section 9 discusses future works and concludes the paper.

2. Related works The role assignment issue in role-based information systems has been dealt with in providing administrative convenience since the assignment task is generally considered to be administrative human work. A simple administrative model for the assignment called user-role assignment (URA) model is suggested (Sandhu & Bhamidipati, 1997; Sandhu, Bhamidipati, & Munawer, 1999). The goal of the URA model is to control the assignment by imposing restrictions on which users can be assigned to a role (Oh & Sandhu, 2002). Based on the restrictions, each administrative people can have authority to assign a range of roles to users who previously satisfy designated prerequisite conditions. This enables the assignment task to be decentralized to some degree. The URA model, however, focuses on the authorization of the assignment, but does not provide a concrete methodology for the actual assignment. Trustworthiness is generally used for the actual assignment since external users obtain access permissions to various resources in the system by being assigned to roles and subsequently can affect the system’s reliability (Chen & Chen, 2009; Saffarian et al., 2009). Several approaches have been proposed to dynamically assign roles to humans based on such trustworthiness (Chadwick, Otenko, & Ball, 2003; Herzberg, Mass, Michaeli, Ravid, & Naor, 2000; Li & Mitchell, 2003). In these approaches, a mutual trust between the access requestor and provider is established based on credentials issued by a trusted authority. Each provider regulates accesses to its resources by asking the requestor to provide a set of credentials that authenticate the requestor as a valid and trusted user (Saffarian et al., 2009). The assignment then takes place. However, it is more important to consider whether humans have enough abilities to meet the requirements of roles rather than whether they are reliable when they are assigned to roles in knowledge intensive service processes. This consideration deals with the most fundamental question facing administrative people when assigning roles, which humans can successfully carry out the inner activities defined in roles. Al-Kahtani and Sandhu (2002) proposed a model for automatic assignment of roles to users based on a set of rules which is pre-defined by the administrative units in an enterprise. These rules take account of the attributes of users. Users have one or more attribute values which are corresponding to one or more roles. This attribute-based approach enables qualified users to be assigned to roles. However, each attribute value is limited to a pre-fixed set of values which is specified by using integer or enumeration types. Information about roles and humans which is necessary during the assignment cannot be described in such a way. Acuna and Juristo (2004) presented a capability-oriented approach to assigning roles to humans in a software project management by defining a definitive list of general capabilities that are critical in software development. In their approach, general capabilities of the members of a development team are first determined and then various roles needed in the team are described as a set of the capabilities required to perform the activities of processes. Finally, appropriate humans are assigned to roles depending on their capabilities and the capabilities required by the roles. However, in order to deal with a wide range of human processes, other explicit factors such as goals, responsibilities and experiences should be also taken into consideration in the decision on the assignment. Moreover, roles can be continuously created and assigned whenever necessary even though the processes are currently running. In other words,

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the role assignment is not a one-time task but a continuing one throughout the life of the processes. Therefore, it is necessary to allow process participants to freely create new roles not to be bounded by a fixed set. In order to do that, we present a decentralized methodology for facilitating the role assignment based on the several explicit factors. In the proposed methodology, participants can create roles and assign them to appropriate humans based on the factors which are formally described using the ontological approach. The ontological approach enables that the role assignment task can be carried out based on a semantic consideration of the factors. 3. Fundamental principles of role-human assignment We first discuss two fundamental principles of role assignment for human processes. The principles address when and by whom the assignment is performed. One is that roles should not be assigned until the need for activation arises. The role assignment task should be continuously performed throughout the enactment of the processes. The other is that the authority for the role assignment should be distributed, not only to administrative people, but also to participants in the processes. The participants should be allowed to create new roles and introduce other people to the processes by assigning the roles to them. As these principles are essential to deal with the role assignment issue, our methodology is developed according to the principles. Each principle is discussed in detail in the following sub-sections. 3.1. Continuous assignment Although the role assignment is the first step in an enactment of human processes, all the roles do not have to be assigned to humans before the enactment. Since the assignor cannot be convinced that humans are available when they actually play the assigned roles, they should be assigned to the roles when the roles need to be activated depending on the situation at that time. Therefore, the assignment continuously happens throughout the processes. A simple exemplary role-based process model is depicted in Fig. 1, where three roles are involved: Business Analyst, Process Analyst and Architect roles. The oblique lined areas represent where the roles need to be activated. The Business Analyst role is triggered to be assigned when the process reaches the stage A and the Process Analyst and Architect roles are triggered to be assigned when the process reaches the stage B. In order to support such continuous assignment, it is necessary to figure out how to notify the assignor that a role needs to be acti-

vated. HIM has already insisted that the assignment be continually performed, but has not addressed how to trigger a role to be assigned at an appropriate time. For a trigger indicator, conditions, which are described in activities in each role, can be used. The sequence of activities in a role-based process model is not flowcharted in advance but is based on pre- and post-conditions (HarrisonBroninski, 2005). If a pre-condition of a certain activity becomes true, the activity can be carried out; if a post-condition becomes true, the activity can be completed. This type of relaxation allows humans not to depend on a pre-defined sequence of activities but to make a choice among their own activities under the conditions. The trigger mechanism can be implemented using these conditions. For example, if pre-conditions of an activity A1 in Fig. 1 are all satisfied except that the Business Analyst role should be assigned, then the role is now triggered to be assigned and subsequently the assignor is notified that he or she must assign the role to an appropriate human. Similarly, if pre-conditions of an interacting activity I1 are all satisfied except that the Process Analyst role should be assigned, then the role is also triggered. 3.2. Distributed authorization for assignment Role-playing humans proactively participate in the processes by creating new roles and introducing other people to the processes by assigning roles to them. Therefore, the authority for the creation of roles should be distributed not only to administrative people but also to participants in the processes. When a new role is created by a participant, the authority for assignment of the role should be given to the creator, since the creator is naturally knowledgeable about the necessary information relevant to the assignment such as the goal of the role, the capabilities required to accomplish the goal and so on. The authority can be transferred to others whenever the creator wants. For example, after a person has created two roles and assigned the one to a person, he or she can request the newly assigned person to assign the other one. In order to facilitate the distributed authorization for the creation and assignment of roles, the information about roles and humans should be systematically modeled and managed, and all the participants should be able to easily understand and utilize the information. Therefore, it is desirable to describe precisely the meaning of the information. An ontological approach can be applied to increase the understandability of the information through describing the semantic meaning of it. Fig. 2 shows that roles are spawned through the distributed authorization for the creation of roles. Various participant roles are first created during the process initialization by a primitive administrative role such as a Role Manager role, which is always

Fig. 1. Activation of roles through continuous assignment.

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Fig. 2. Spawning participant roles based on distributed administration.

Fig. 3. Structural model for essential information about role and human in assignment.

running in the service-providing company, and then they are assigned by also the administrative role during the process enactment. As the processes are enacted, participants can always create and assign new roles to introduce other people to the processes based on their own decision-making.

4. Overall procedure for ontology-based assignment Based on the above principles, we present a methodology for facilitating the role assignment. Since one needs to consider the information about roles and humans when performing the assignment, the information should be precisely and systematically described. As there is generally considerable information, we just focus on the following essential information: (1) for a role, a goal that is intended to be achieved by a role-playing human and responsibilities that are dealt with during the life of the role and (2) for a human, experiences in terms of a set of roles that a human had played before in other projects or processes and capabilities that the human possesses. For the distributed assignment, the essential information should be clearly understandable to various participants in the service processes. Therefore, we present ontological specifications of the essential information about roles and humans. In order to do that, we first establish a structural model for the information as shown in Fig. 3, which can be a basis for the ontological specifications. A role is associated with a goal by the relationship have goal of and associated with responsibilities by the relationship have responsibility of. A human is associated with capabilities by the

relationship have capability of and related to the roles by the relationship experienced by, which represents that the human has experience of playing the associated roles before. A responsibility can be associated to capabilities by the relationship supported by, which represents that the associated capabilities are vital to satisfy the responsibility. All the information can be intuitively and concretely described using natural language in a human-oriented way. The assignment task can be naturally performed based on the concrete information. The natural language-based description of the information, however, can cause misunderstanding or semantic inconsistency problems due to the possibility of different interpretations of the description. Moreover, it generally causes the workload of the assignor to be overloaded since they should manually check all the information whenever necessary. In this way, the assignment becomes a cumbersome task. Therefore, we introduce a simplified approach of utilizing abstract information to facilitate efficient processing of the information based on the computerized support. In this approach, the abstract information about goals, responsibilities and capabilities is described in a verb-object format, which is defined as: the first word is a verb, the second word is a parent object which is represented as a noun and others are child objects which are represented as a combination of a preposition and a noun. Fig. 4 illustrates a structure of an example abstract goal description. The word make is used as a verb and the word architecture is used as a parent object. A child object is represented as a combination of the preposition for and the noun system solution. Since a word may have several syntactic categories and subsequently have several different meanings, WordNet defines it with

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where process participants can create roles whenever they want during the process enactment, we use WordNet as a basis for building the ontologies. People can easily define new roles with necessary information through utilizing rich semantics of words and concepts provided by WordNet. In order to help readers understand our assignment approach well, we give a simple example scenario. Example Scenario. Virtual Consulting Co.

Fig. 4. Structure of example abstract goal description.

several senses which are represented as the sense categorization. Therefore, all verbs and nouns are internally described with the sense categorization. In order to resolve the semantic inconsistency problem and facilitate the computerized support, the semantics of words that occupy the verb and object spots are precisely described by formal and machine-processable ontologies. Consequently, this approach can lighten the workload of assignors by facilitating the assignment task based on the computerized support. The approach is similar to keyword-based approach but does more than that in that it can represent the information more accurately and precisely, and subsequently it can enable query for the information to produce more meaningful results. An overall procedure for the role assignment based on this approach is shown in Fig. 5. The procedure is composed of three main phases: initialization, identification and negotiation. In the initialization phase, the ontological specifications of roles and humans are defined according to the structural model. When one wants to create a new role along with associated information, the creator first examines the existing information and then reuses it or creates new information by relating the existing one. The creation of roles can be carried out by participants in the service processes during the process enactment as well as by a primitive role during the process initialization. The information about humans is originally defined when they are employed in the service-providing company and then changed and updated by themselves or a primitive role such as a Human Resource Manager role whenever necessary. In the identification phase, appropriate candidates for a certain role are identified by applying inference rules to the ontological specifications. Two methods are applied simultaneously for the identification of candidate humans who satisfy the requirements set out in the role. One is an experience-based identification which aims to identify candidates who have experience of playing other roles which have a similar goal to the role, and the other is an ability-based identification which aims to identify candidates who have enough capabilities to satisfy the responsibilities of the role. To realize these two identification methods, inference rules for each method are set out clearly and concisely in this phase. In the negotiation phase, the assignor negotiates with the identified candidates to gain a commitment to play the role through a variety of means. Since the negotiation-based assignment is performed manually in accordance with the candidates’ willingness, we focus on the initialization and identification phase.

5. Ontological specifications of roles and humans In order to enable the role assignment to be performed based on the semantic consideration of the information about roles and humans, we describe the information as ontologies using Topic Maps. Moreover, in order to facilitate the decentralized assignment

As an IT consulting company, Virtual Consulting Co. provides a wide range of project management services to the overseas clients. It generally has a variety of information about its own roles and human employees. A small subset of the information is illustrated in Fig. 6. The Systems Designer role has the goal of making an architecture for system solutions and the Systems Analyst role has the goal of coordinating choice of system solutions. They have the responsibilities of P1, P2, and P3, P4, respectively. The human Terry has the capabilities of C1, C2, and C4, and the human Joe has C1, C3 and C4. They have experience of playing the Systems Designer and Systems Analyst roles, respectively. The support relationships between responsibilities and capabilities are displayed in the lower part of Fig. 6. Using this scenario, we will explain how to specify the information ontologically, how to create new roles by relating them with existing ones and how to identify candidate humans appropriate for the new role in the rest of this paper. However, before doing that, it is necessary to first discuss why and how Topic Maps and WordNet can be used in the role assignment. Therefore, we present an ontological specification approach using Topic Maps and WordNet as discussed in Section 5.1. Based on the approach, ontological models for roles and humans are presented in Sections 5.2 and 5.3, respectively, using the example scenario. 5.1. Ontological specification approach for specifying information about roles and humans In this paper, Topic Maps is used for the representation of the information about roles and humans, and for the definition of semantics of terms. Topic Maps, an international standard technology for describing knowledge structures, aims to alleviate information glut and improve findability of information (Pepper, 2008). At the heart of Topic Maps is subject-centricity since the whole purpose of creating information is to capture knowledge about certain subjects in order that they can be shared and reused. Ineffable subjects are surrogated by topics and any kind of statements about the subject can be made by associations. An association can involve any number of subjects since it is n-ary by default, and even undirected (Raffeiner, 2005). The reason Topic Maps is used in this paper is twofold. First, the abstract description of goals, capabilities and responsibilities, which is described in a verb-object format, can be completely described using the associations. An object is described by an n-ary association and then the association is reified into a topic that is eventually related to a verb by a unary association. Second, Topic Maps is more semantically stable than other ontology languages such as Web Ontology Language (OWL), which adopts an objectoriented modeling approach. This is because attributes are not used in Topic Maps. The object-oriented approach represents knowledge with objects for terms and attributes of the objects for relationships between them. However, the approach usually suffers from various changes caused by attributes evolving into other constructs (Halpin & Bloesch, 1999). When a concept which is defined as an attribute of a particular object needs to be redefined as an object, various changes should be accompanied such as replacing queries and constraints. Since an ontology designer

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Fig. 5. Overall procedure for role assignment based on the ontological specifications.

cannot be sure about the future modeling needs, use of attributes in the base model decreases semantic stability (Halpin & Bloesch, 1999). In order to make Topic Maps be enforced by systems, XMLbased interchange syntax for Topic Maps, XML Topic Maps (XTM), is presented (ISO, 2007). XTM enables Topic Maps to be interchanged between systems. As one of the most important aspects of using ontology is findability of information, ontology query languages are necessary. Hence, tolog, a logic-based query language for Topic Maps, is proposed by Ontopia. If users ask tolog in which cases a certain assertion holds true, tolog will respond with all the sets of values that make the assertion true (Garshol, 2006). We build machine-processable ontologies for the information about roles and humans using XTM, and define various infer-

ence rules and query models to identify candidate humans for a certain role using tolog. The authority for the creation of roles should be distributed to process participants. Therefore, utilizing a common ontology which defines the semantics of general linguistic words and domain specific terms is an appealing solution to support people to describe precisely the information of roles. The most representative common linguistic ontology is WordNet which is suggested by Cognitive Science Laboratory of Princeton University. It is a lexical ontology for English based on psycholinguistic principles. WordNet is composed of four nets that represent the main syntactic categories: nouns, verbs, adjectives and adverbs (Gomez-Perez, 1999), and they are all organized in a network by means of a small set of semantic relationships including synonymy (Miller, 1995).

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Fig. 6. Subset of information about roles and humans in Virtual Consulting Co.

The semantic relationships apply broadly throughout English and are familiar to common users who need not have advanced training in linguistics to understand them (Miller, 1995). Therefore, WordNet can be a basis for modeling ontologies of roles and humans by providing a network of meaningfully related words and concepts. Fig. 7 depicts a layered approach to the ontological specifications using Topic Maps and WordNet based on the structural model for the information about roles and humans. Ontologies of roles and humans are built using Topic Maps according to the structural model. Although WordNet provides rich semantics of general words and concepts which are generally sufficiently comprehensive to capture the information, domain specific terms must be also necessary. Therefore, the ontological specification approach is composed of two layers as depicted in Fig. 7. The first layer describes the semantics of domain specific words based on the meaningful general words provided by WordNet and the second layer describes specifically the information about roles and humans using Topic Maps based on the general and domain specific words. In this way, it can facilitate decentralized building of the ontologies through allowing any participant to create new roles with designated information by referring the semantic definitions of various words. 5.2. Ontological specification of roles According to the structural model, the information about a role consists of a goal and responsibilities. In order to provide the ontological specification of a role along with the information, a detailed structural model is proposed as shown in Fig. 8. Based on the onto-

logical specification of a role, we present how a role ontology can be built using Topic Maps. The upper part of Fig. 8 shows how a goal is specified along with the role. The goal is related to the role by an association have goal of and defined as a topic which is reified from a unary association containing a goal verb and a goal object, each of which is also defined as a topic. The unary association represents the abstract description of the goal. The goal object topic is reified from an nary association containing a noun as a parent object and goal compounds as child objects. Each goal compound topic is also reified from a binary association containing a preposition and a noun. The concrete description of the goal certainly described using natural language is related to the goal topic through an occurrence representing a particular kind of relationship in Topic Maps. Various verbs and nouns used to describe the abstract description of the goal are described in a domain ontology on the whole based on the words and concepts WordNet provides. The lower part of Fig. 8 shows how a responsibility is specified along with the role and capability. The responsibility is related to the role by an association have responsibility of and defined as a topic which is reified from a unary association representing the abstract description of the responsibility. Moreover, the responsibility is related to capabilities by an association supported by, which represents that the related capabilities can contribute to satisfy the responsibility. The abstract description of the responsibility is also written using combinations of words in WordNet and the domain ontology in the same manner as the one of the goal described above. Fig. 9 depicts an exemplary ontology model for a Systems Designer role based on the detailed structural model.

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Fig. 7. Layered approach to ontological specifications using Topic Maps and WordNet-based domain ontology.

Fig. 8. Detailed structural model for ontological specification of role.

The upper part of Fig. 9 shows a textual representation of the information about the Systems Designer role. A goal of the role is to make an architecture for system solutions and one of the responsibilities is to analyze the needs of end users. The responsibility is supported by the capability of analyzing the requirements of end users. The middle part of Fig. 9 shows a structural model for ontological representation of such textual information and the lower part of Fig. 9 shows an XTM representation of the ontology corresponding to the structural model. General

words are first defined as topic types in the domain ontology based on the word definitions given on WordNet, and then topics and associations are defined in the role ontology by instantiating them. All words used in the abstract descriptions are defined using the sense categorization of WordNet. In each sense of a given word, a group of synonyms is also defined in WordNet. Therefore, using the synonymous relations, we can figure out the semantic similarity between the words used in the abstract descriptions.

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Fig. 9. Exemplary ontology model for Systems Designer role.

5.3. Ontological specification of humans In order to facilitate the role assignment, the semantics of the information about humans should be also precisely described. According to the structural model, the information about a human consists of experienced roles and capabilities. A detailed structural model for the ontological specification of a human is proposed as

shown in Fig. 10. A human ontology is built based on the detailed structural model using Topic Maps in the same manner as the role ontology is built. The capability is related to the human by the association have capability of and defined as a topic which is reified from a unary association containing a capability verb and a capability object, each of which is also defined as a topic. The association is utilized

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Fig. 10. Detailed structural model for ontological specification of human.

in the assignment stage when enrolling capable humans to the candidate list for a particular role, who have appropriate capabilities satisfying the required responsibilities described in the role. Experiences of the human are represented in terms of a set of roles that he or she had played before and depicted as the association experience. The association is utilized when enrolling experienced humans to the list, who have experience of playing other roles that have a similar goal to the target role. Fig. 11 depicts an exemplary ontology model for human Terry based on the detailed structural model. The upper part of Fig. 11 shows a textual representation. One of the capabilities Terry possesses is to analyze the requirements of end users and he or she has the experience of playing the Systems Designer role before. The middle part of Fig. 11 shows a structural model for ontological representation and the lower part of Fig. 11 shows an XTM representation corresponding to the structural model. General topic types are defined in the domain ontology and a topic Terry that is an instance of the topic type human is defined by associating with the topic requirements analysis as his or her own capability and the topic Systems Designer as an experienced role. 6. Role creation procedure Roles can be created by any participant even during the enactment of processes. When a role is newly created, the role and human ontologies are naturally forced to be changed and evolved since the new role needs to be related to the existing responsibilities and capabilities in the ontologies. Therefore, the role and human ontologies should be open to the participants to access and evolve the ontologies. In order to support the complicated role creation, we present a procedure for creating roles as depicted in Fig. 12. The procedure shows how a new role along with associated information is created and how they are related to existing information within the role and human ontologies. The procedure consists of four phases. In the first phase, a creator creates a new role with general information and describes a goal of the role abstractly and concretely. The abstract description is described using semantically rich words that WordNet and the domain ontology provide. In the second phase, several roles which have a similar goal with a newly created role are identified. The similarity relationships between the role and other existing roles in the role ontology are derived from the comparison of the abstract descriptions of their own goal. Since the abstract description is represented in a verb-goal object format, semantic similarity be-

tween words that occupy the verb and object spots can provide a clue for establishing the semantic relationships between roles. There are a variety of semantic relations including synonymy between words in WordNet. Therefore, we define inference rules for assessing the similarity of words used in the abstract descriptions. The rules are defined using the tolog query language since the whole descriptions are formalized with Topic Maps. However, our assessment approach based on the similarity between words in the goal descriptions must be a partial solution to the similarity problem of roles. The approach just retrieves a large variety of roles which have the possibility of being similar to the new role. Hence, in order to elaborate the assessment of the similarity of roles, the creator’s intervention in filtering the roles by referring the concrete descriptions of goals is imperative. This is why the role assignment task including creating roles and assessing similarities is considered to be human work. In the third phase, similarity relationships are established. Various relationships must be complexly interwoven in the role ontology, and consequently it is necessary to explicitly represent who made the relationships to clarify where the responsibility for them lies. For that, a tag indicating the responsible person is attached to each relationship. Moreover, since different policies can be applied to each relationship, the applied policy should be clearly described in the relationship. In the last phase, the creator defines a set of responsibilities required to carry out activities in the role by referring responsibilities of the filtered roles. Sets of capabilities are also defined and related to the corresponding responsibilities. The creator can, of course, create new responsibilities and capabilities, and relate them each other by applying the association support or supported by. A procedure for the goal-oriented similarity assessment of roles with inference rules used in steps of the procedure is shown in Fig. 13. A concrete query procedure for the similarity assessment using the inference rules is also presented in the lower part of Fig. 13. As stated above, the role creation task is highly dependent on the ability of humans. Therefore, a computerized support system is valuable in helping people carry out the task. The inference rules and a query procedure we propose can be a basis for developing the support system. The procedure for assessing the similarity of roles consists of three steps. A brief explanation of each step is given below.  Step 1: it is first defined how to assess the similarity of the abstract descriptions. Two main criteria apply to the similarity assessment: (1) whether the verb is used in the assessment or not and (2) how the goal object which is represented as a com-

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Fig. 11. Exemplary ontology model for human Terry.

bination of a preposition and a noun is decomposed and used. The creator establishes a query policy based on such criteria to assess the similarity.  Step 2: according to the established query policy, similar words to the words in the abstract description of the new role’s goal are identified based on the synonymous relations between words described in WordNet and the domain ontology. For the identification, the following two inference rules are defined: (1) a rule find_associations for deriving word similarity associations in which similar words are involved and (2) a rule equivalent for identifying semantically similar words from the derived associations.

 Step 3: roles are identified which use the semantically similar words to represent the abstract descriptions of their goals. For the identification, the following three inference rules are defined: (1) a rule find_roles_from_verb for deriving roles which use the similar words as a verb for the abstract description, (2) a rule find_roles_from_nouns_po for deriving roles which use the similar words as a parent object in the goal object and (3) a rule find_roles_from_nouns_co for deriving roles which use the similar words as child objects in the goal object. The concrete query procedure aims to identify a set of similar roles which have a similar goal to the new role using the inference

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Fig. 12. Procedure for creating new role.

Fig. 13. Procedure for goal-oriented similarity assessment of roles.

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Fig. 14. Exemplary procedure for creating Architect role.

rules. First, a query policy is established since details in the procedure may differ according to the applied policy. And then, the abstract description of the goal is decomposed into a verb and a goal object which is also decomposed into a parent object and child objects. The parent object spot is occupied by a noun word and the child object spot is occupied by a combination of preposition and noun words. Using the above rules, several roles that have a similar goal can be identified. After identifying candidate roles, the creator should determine which roles are actually similar to the new role among them based on the deep consideration of the concrete descriptions of their goals and establish a similarity relationship between the new role and similar roles. Based on the similarity relationships, we can identify candidate humans for the new role who have experience of playing other similar roles in the role assignment stage. Since the creator can create new responsibilities and capabilities whenever he or she wants, it is necessary to describe them by relating them to existing ones in the role and human ontologies. Inference rules for assessing the similarity are also helpful to establish the relations. The rules can be obviously formulated in the same manner as the above rules since the abstract description of the responsibility and capability is represented in the same format as one of the goal. The relationships between humans and capabilities in the human ontology can be established in an active manner by allowing humans to create new capabilities and relating themselves to those capabilities based on their own decision-making. Fig. 14 shows an example procedure for creating a new role – Architect. In the first phase, an abstract goal of the role is described as to create a plan for IT systems and then it is concretely stated. In the second and third phase, a query policy is created as follows: (1)

the verb create is mandatory and (2) the goal object plan for IT system should be exactly matched. Based on the policy, similarity assessment is carried out in two steps. In the first step, the abstract goal description is decomposed into verb, parent object and child objects, and then similar words to the decomposed verb and nouns are identified using the presented inference rules. For the verb create, make-verb-3 and produce-verb-2 are retrieved, and for the noun plan, architecture-noun-4, design-noun-2 and blueprint-noun-1 are retrieved. For the noun IT system in the child object, system-solution-noun-1 is retrieved. After that, roles which describe their own abstract goal using these similar words are identified. In this example scenario, one role Systems Designer role is identified. We call this first step the system-driven identification since the overall identification process is mainly carried out by the system based on the query policy and inference rules. In the second step, similarity relationships are determined by the creator’s decision with the deep consideration of the concrete goal description of the Systems Designer role. We call this second step the user-driven identification since the decision-making of the creator is a critical element during the identification process. In the last phase, the creator defines the Architect role’s responsibilities by referring the Systems Designer role’s responsibilities. The responsibility P1 is from the existing one and NP is newly created. The NP is associated with the capabilities C1 and C4 by support relationships. 7. Ontology-based identification of candidate humans Relevant roles are gradually assigned to appropriate humans when the roles are triggered to be activated during the enactment of processes. A way for identifying candidate humans who are

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Fig. 15. Inference rules and query model for ontology-based identification of candidate humans.

appropriate for the triggered roles based on the ontologies of roles and humans is depicted in Fig. 15 along with inference rules and a query model. The ontology-based identification is carried out by the following two steps: (1) a goal-oriented identification for identifying experienced humans who have experience of playing similar roles to the triggered role and (2) an ability-oriented identification for identifying capable humans who have sufficient capabilities to satisfy the required responsibilities of the triggered role. Two inference rules find_humans_from_similar_roles and find_humans_from_ abilities are used in these steps, respectively. A set of candidate humans can be derived from the query model using the inference rules which is shown in the lower part of Fig. 15. Fig. 16 illustrates the results of the candidate identification process for the Architect role. From the goal-oriented identification, Terry is determined to be an experienced candidate since the Systems Designer role has a similarity relationship to the Architect role and Terry has experience of playing the Systems Designer role. From the ability-oriented identification, Terry and Joe are determined to be capable candidates since they both have an enough capabilities to satisfy the required responsibilities of the Architect role. The implicit factors such as availability and willingness of candidates should be also considered when assigning the Architect role

to the identified candidates. Therefore, a negotiation to gain a commitment to play the Architect role should be carried out between the assignor and the identified candidates. Although the manual negotiation is essential in the assignment, our methodology can facilitate the assignor’s work by providing a set of suitable candidates for the role. Moreover, it provides a way to manage the information about diverse roles and humans in the service-providing company.

8. Implementation of a prototype We have implemented a preliminary prototype of a service process management system focusing on the management of roles. Fig. 17 represents diagrammatically the overall architecture of implemented system for facilitating human works in the service processes especially creating new roles and assigning them to appropriate humans. A personalized application provides a wide range of information to role-playing humans such as which activities are enabled and which roles are triggered to be activated. In the application, two main facilities are provided. One is a process manager which visualizes and manages the overall service processes and guides the

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Fig. 16. Results of candidate identification for Architect role.

Fig. 17. Overall system architecture.

role-playing humans to perform appropriate tasks at appropriate times. The process manager is associated with the organizationwide repository of process assets. The other is a role manager which facilitates the humans to create new roles and assign them to other humans. The role manager is associated with the ontologies for the information about roles and humans, and the definitions of domain specific and general words. When a new role is created, a goal intended to be achieved by the role is first described using the domain ontology and a query policy is established using the policy module. Based on the established policy, similar roles to the new role are identified using the query module. Finally, the role is stored in the role ontology along with newly created information such as a goal, responsibilities and necessary capabilities using the update module. When a certain role is triggered to be activated, appropriate candidates for the role are identified through the query module. The detailed information

is provided to the assignor from the evaluation module and final candidates are selected using the decision module. The assignor negotiates with the candidates to gain a commitment to take on the role through messaging. Fig. 18 shows the implemented prototype of the process management system with the role assignment application. The prototype is implemented with java. We used Ontopia 5.0.0 API for controlling XTM ontologies, tolog inference rules and query models. Moreover, to search the WordNet information, we also used JWI 2.1.5 API developed by MIT Java WordNet Interface Team. As a development platform environment, we used Eclipse for java IDE and Windows XP Professional. Java 1.6.0 is used for the java virtual machine. After human workers log into the system by selecting one role among active roles they are now taking on, they can check the overall status of the processes, messages and enabled activities. They are also notified which roles are triggered and wait to be as-

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Fig. 18. Prototype of service process management system with role assignment application.

signed. The Architect role is currently triggered in Fig. 18. When the assignor clicks the ‘‘Assign’’ menu item, the role assignment application identifies candidate humans appropriate for the role and presents coherent information about each candidate to facilitate the assignor to decide who can be enrolled in a final candidate list. After selecting Joe and Terry as the candidates, the assignor can negotiate with them to gain a commitment to play the role. When the negotiations are finished, the assignment process will be closed and the Architect role will be removed from the list of the waiting roles. In order to facilitate the human workers to proactively participate in the processes, the authority for creating roles should be distributed to themselves. Therefore, the prototype of the role creation application is also implemented in the process management system as shown in Fig. 19. A procedure for creating a new role Information Systems Liaison is illustrated in Fig. 19. First, the creator defines a goal abstractly and concretely. The application allows the creator to describe the abstract goal in a verb–object format using the domain specific and general words by providing the ontology browser. After defining the goal, a query policy is created as follows: (1) the verb organize is optional and (2) the noun IT system in the goal object technical specification of IT system is mandatory. From the policy, three roles, Systems Designer, Systems Analyst and Architect roles, are retrieved and displayed. Among them, the Systems Analyst role is determined to be similar to the Information Systems Liaison role by the creator. That is, a similarity relationship is established

between them. Information about the creator and the applied policy is attached as a tag to the relationship in order to enable any other participants to reevaluate and evolve them. The similarity relationship is utilized when identifying experienced candidate humans in the role assignment application. The creator can change the policy to receive different results at any time. Therefore, the application can provide various valuable options to the creator to determine similar roles. Responsibilities belonging to the similar role, Systems Analyst role, and associated capabilities are also displayed so that the creator can reuse them to define the information about the Information Systems Liaison role. The creator, of course, can create new responsibilities and relate them to existing capabilities by clicking the ‘‘Associate Capabilities’’ menu item or to new capabilities by clicking the ‘‘Create Capabilities’’ menu item.

9. Conclusions The knowledge intensive service processes should be managed in a human-oriented way since human workers who naturally undertake complex operations of an intellectual nature in the processes are the most valuable resources for service-providing companies. For the human-oriented management, a role-based approach has been widely applied. The foremost step in the rolebased human process management is to assign relevant roles to appropriate human workers.

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Fig. 19. Prototype of role creation application.

This paper presented two fundamental principles of the role assignment and proposed an ontology-based assignment methodology corresponding to those principles. The proposed methodology specifies the information about roles and humans ontologically and identifies appropriate candidate humans for a certain role based on the ontological specifications. From the proposed methodology, human workers can be notified which roles are triggered to be activated and wait to be assigned. Moreover, they can be provided appropriate candidate humans when carrying out the assignment task. The advantages of the methodology are as follows. First, the methodology provides the capability of facilitating the role assignment task in a human-oriented way since it is developed upon the principles which are essential to make the assignment work process to be compatible with the general human work behavior. Second, it can efficiently manage the diverse information and help the assignor carry out the assignment task based on the deep consideration of the information through describing the ontological specifications of roles and humans. Third, it can lighten the assignment workload by providing a small set of appropriate candidates. The assignor need not communicate and negotiate with all human workers to result in an agreement on playing a certain role. Fourth, the efficiency of the assignment task can be increased since the task can be streamlined by using the computerized support system which is built based on the proposed methodology. In order to enrich the proposed methodology further, more work should be done. In this paper, although we insist that the authority to create and assign roles be distributed not only to administrative people but also to participants in the service processes, we do not deal with how to manage the distributed authorization. We simply assume that any human worker can create new roles; the assigning authority of the newly created roles is conceded to the creators themselves and the authority of other roles defined at the process design stage is already defined at that time. Therefore, further research should be directed at determining

how to actually distribute the authority and how to transfer the authority to others. Moreover, in this methodology, the abstract descriptions are defined separately from the concrete descriptions. It would be a cumbersome thing to do. Thus, we think that research on how to automatically generate the abstract description from the concrete description using natural language processing techniques would be a valuable future work. Finally, the range of processes in which newly created roles can participate should be limited to prevent the imprudent creation of roles. That is, each role-playing human should be authorized to create new roles in the limited range of processes.

Acknowledgement This research was supported by the National Research Foundation (NRF) of Korea (No. 2009-0079693).

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