• The actual roles are a complete and definite set that have semantics in the considered organizational context.
• The role mining problem will define a set of potential roles. We can only come with an incomplete solution to the role mining problem. By means of approximation and heuristic, we could find an almost optimal solution or one that works reasonably well, so a subset of the all the potential roles.
• Whereas all the actual roles set are assumed to exist and be useful in an enterprise context from the set of candidate roles a overwhelming majority will be eliminated.

So instead of trying to find all roles, why not just redefine the problem and take into consideration the correct premises to derive the set of correct roles. It all comes in the end to the old saying, why buy the cow (i.e. define the set of ALL candidate roles) when you can have the milk for free (i.e. the actual roles)?

In conclusion, bottom up role definition focuses on analyzing the entitlements in target systems and is typically performed by a technical team, while the top-down strategy is centered on user attributes and is performed by a business team. Regardless of the approach, the enterprise should first capture the scope for of role definition, and then decide on the strategy to use. Two main objects are prevalent when defining roles: defining roles for administrative purposes and defining roles for security and compliance purposes. First, when the goal of role definition effort is to validate and verify the technical environment and to correct inaccurate functional and security controls, then a bottom-up strategy is recommended. This strategy starts with collecting and analyzing entitlements. The roles resulting when implementing a bottom-up strategy can be both technical roles and business roles. In order for the resulted roles to become usable they need perspective from business users and owners. Second, when the main objective of role definition is to provide validate and verify the administrative environment and to correct inaccurate structural controls, then a top-down approach is recommended. This strategy focuses on creating business roles based on analyzing job responsibilities as well as the relationship among responsibilities. However in order for these roles to become usable they need perspective and input from resource owners.

This differentiation allows the two strategies to be implemented independently during the role definition process. Up to a certain point, the two strategies can be applied in parallel. They should meet in the middle to create a mapping structure between the business roles and technical roles. Technical teams can make considerable progress toward creating a role structure for an enterprise, but the roles must ultimately be approved by business owners. Similarly, business representatives are able to create high-level role definitions but will have some difficulty in mapping these roles to the entitlement infrastructure.

After the strategy (bottom up, top down or a combination of both) for role definition is established based on the project scope, the process scope must be established. The role definition process depends on what needs to be done in order to define roles and to some extent how it should be done (e.g., establishing some role guidelines, a quality model for role definition). Both top-down and bottom-up strategies can be tactically implemented using processes like role engineering and role mining. If the role definition process scope is to enumerate the set of roles without cardinality constraints, the process tries to answer the question “how many roles?” and not “why so many roles?” In this case, the outcome of the definition effort will be represented as actions to be taken on the entitlements and users for which data is being or has been collected. This process applies best to organizations with a small number of employees, or with highly specialized business units with a small number of users. However, if the process of role definition aims to correct or improve user attributes and entitlement data and/or the workflow of the administrative tasks in the future, then cardinality constraints must be taken into consideration and the question that is important here is “Why so many roles?” In this case, the outcome of the definition effort will be actions to be performed on the process that produced the data. Therefore, the focus of the process will be on data cleaning, data consolidation and data synchronization.

The role definition process can be viewed by extrapolation as requirements analysis. Coyne was the first one to use the term role engineering (Coyne, 1996). Requirements analysis methods can be regarded as process-oriented, data-oriented and control-oriented (Thayer & Dorfman, 1997). From the point of view of role definition, a process-oriented method would take into consideration the way the systems transform user and entitlement data into roles, with less emphasis on user and entitlement data itself, and also with less emphasis on control aspects. Data-oriented methods for role definition would emphasize the state of the provisioning system as a user and entitlement data structure. Control-oriented methods would emphasize synchronization, exclusion, concurrence, and role activation and deactivation. In conclusion, all three methods mentioned in this paragraph can be used in the activities performed at different stages in a role definition effort. Careful consideration should be given to each phase scope, and an appropriate engineering method should be selected.
Requirements engineering activities associated with role definition may be classified in terms of:

• role elicitation: discovering, reviewing, and understanding roles and constraints
• role analysis: defining role structure and constraints
• role specification: refining and documenting roles structure and constraints, clearly and precisely
• role verification: ensuring that the roles are complete, correct, consistent, and clean

Data mining is the use of automated data analysis techniques to uncover previously undetected relationships among data items. Data mining often involves the analysis of data
stored in a data warehouse. So, by extrapolation, role mining can be defined as the use of automated data analysis techniques to uncover previously undetected relationships among users and entitlements. Role mining involves the analysis of user information (attributes and entitlements) stored in various systems. Data mining techniques can be used to perform entitlement-to-technical-role associations. In the same way, user attributes to business role can be discovered using pattern recognition techniques. But the final entitlement-to-technical-role and business-role-to-user attributes definition decisions can only be done in a business centric process. Data mining activities associated with role definition may be structured in terms of:

• role data collection
• role data preparation
• role modeling
• role evaluation

Data mining for role definition is nothing more than a tool that can assist the role definition process.  But this approach can reduce the problem space to either solve the problem or reduce the problem enough so that one can find the optimum solution with a (worst-case) exponential method.  However, it is very difficult to use data mining approaches to mine for roles in an industrial environment. The main reason is that they fail to discover roles with semantic meanings. Existing role mining problem definitions only use user entitlement information. Since entitlements are symbols without meanings, this limits the ability to identify usable roles. Mining on both user attributes and entitlements might be a future research direction to consider.

By extending this definition to an enterprise environment, roles can be defined as company specific norms (duties and responsibilities) associated with a given functional or organizational position. Hence, roles are defined by operational needs and functional constraints. Roles limit access to data and enable administration of user and entitlement objects. Roles can be used to describe a class of entitlements from a technical point of view. They are also used by business units to represent aspects of the organizational structure. Organizations often use the term role to cover both meanings, and then it becomes immediately very difficult to define roles. That is why, in the context of role definition for provisioning, we will use two types of roles: business roles and technical roles.

A business role (organizational or structural role) is an articulation of a business responsibility required to perform a job function. A business role is a named collection of business functions (duties or responsibilities) that can be performed by users in an organization. Business roles are derived from operational procedures and policies. They are created and managed by business users, such as managers and team leaders. A business role can be either static or dynamic. Dynamic business roles depend on rules to determine role-to-user assignment. Allocation rules define who must be assigned to a particular role and under what circumstances. For example, a business unit manager, John, can create a rule to grant the business role, Statistician, to all active users in the Statistics department who have the job description Statistician. All users in the selected department who meet the condition described by this rule are automatically added to the list of users of the Statistician role. Automatically entitling users to business roles is based on data available from human resources target systems. When attribute values that control automated assigned roles change, user assignments to roles will change. Static business roles assign roles through manual-requests. Unlike dynamic business roles, that rely on rules, static business roles must be requested manually for each individual user that is entitled to the specific role. For example, consider the static business role “mission travel”. John, a manager, decides to assign this role to his employee Jane who is traveling on a mission to Europe. John must manually request this role for Jane. Ideally, when Jane comes back from the mission, John should not have to manually revoke the role from Jane. The role definition should consider environmental attributes (e.g., role duration), and the role assignment should automatically be revoked when a given condition (e.g., role duration is less than 3 months) is satisfied.

A technical role (IT or functional role) is a named collection of entitlements and can be mapped to business roles in order to assign users to a set of entitlements. Suppose that Jane is a new employee in the Statistics Department of Mother Organization and that among her main responsibilities is data dissemination to partner organizations. Then John, Jane’s
manager, should give her access to the Data Dissemination business role. The data dissemination role is further divided into the technical roles Dissemination Access to Partner
Organization 2 and Dissemination Access to Partner Organization 1, depending on the information system used for exchange between Mother Organization and the Partner
Organizations. In other words, the technical role Data Dissemination to Partner Organization 1 is a collection of entitlements: Create New Data Set, Publish Data Set and See Reports of
Published Data on a specific target system used for data exchange between Partner Organization 1 and Mother Organization. Technical roles can be refined based on target systems (e.g., various exchange systems between organizations), based on various levels of security within the same target system, or based on user attributes.

The industry is split into two camps when it comes to role definition: the pragmatic one thinking that there is no need for multiple categories of roles, (Courion, 2007) and the more academic one believing that there is a need for distinction (Eurekify Ltd, 2008). I am in the latter camp and think that business and technical roles have practical applications.
There is an immediate and urgent need for role-based provisioning, which may not involve role types. However, using the business and technical role types generates options for additional uses of each type within and outside the span of provisioning. More this differentiation induces the necessary level of abstraction between technical and business organizational levels. The main argument in favor of using role types, is that they make role-based provisioning easier to understand over time. Hence, the distinction between business and technical helps role maintenance. One additional argument in favor of the separation between business and technical roles is that it allows implementation of management and security controls, such as:

• all business roles must be approved by the personnel administrative department
• all business roles must be approved and activated by business units managers
• only business roles can be directly assigned to users upon manual-request
• business roles can only contain other roles, and not direct entitlements
• technical roles can only be approved by resource owners