【文章內(nèi)容簡介】 time an administrator sets up role authorizations, while dynamic separation of duty enforces the rule at the time a user selects roles for a session. Role Administration and Visualization The roles are established, manipulated and viewed using the RBAC/Web Admin tool. The Admin tool allows system administrators to create and define roles, role hierarchies, relationships and constraints. Once the RBAC framework is established for the anization, the principal administrative actions are the granting and revoking of users into and out of roles as job assignments dictate. These maintenance tasks are easily performed using the Admin tool. Additionally, the Admin tool is being enhanced to utilize the Virtual Reality Modeling Language (VRML, pronounced 39。vermal39。). VRML is an interactive, interworked, 3D graphics language for the Web. It is used to represent graphics, test, sound, and links to other content as either a static or dynamic picture on the Web. The inclusion of VRML into RBAC lets system administrators use an interactive puter model to check and validate the role structure, relationship, and privileges. Being able to view and interact with plex models, allows the administrator to identify conflicts, eradicate flaws and improve the implementation early in the RBAC setup. The VRML ponent will enable authorized users to navigate the RBAC database, finding and linking roles, and displaying attributes and graphics associated with those roles. By presenting a 3D model of established roles, the user can easily see which roles are mutually exclusive as well as the hierarchical structure of related roles and conflicts between roles (see Figure 2). VRML39。s navigational controls allows the user to interactively 39。walkthrough39。 and manipulate the view perspective of the 3D model, known as a scene graph. For example, the scene graph can be rotated to show the 39。backside39。 of the graph where role relationships may have been obscured when viewed as a 39。flat39。, 2D graph. To improve readability, clarity and flexibility, the role hierarchy is anized into layers, where each layer contains another level of detail. By 39。clicking39。 on a role, the role opens to reveal the next layer of related roles or information about the role, ., the privileges associated with that role or a user membership list. RBAC Example Consider the branch office of a bank. In this environment, there are roles such as branch manager, teller, and account representative, as illustrated in Figure 2. The graph structure shows role hierarchy. The role financial_advisor inherits the role account_rep. An individual authorized for the role financial_advisor is permitted to perform all of the operations permitted to an individual authorized for the role account_rep. Thus, an individual in the role of financial_advisor is able to create and remove accounts. Because account representatives, branch managers, internal auditors, and tellers are all employees of the bank, their corresponding roles inherit the employee role. In Figure 2, the role account_rep is highlighted, appearing as a dark sphere, in order to show the other role relationships for account_rep. The roles teller and account_holder are shown as yellow rectangular solids to indicate that these roles have a Dynamic Separation of Duties (DSD) relationship with the role account_rep. This relationship is a conflict in interest relationship indicating that an individual acting in the role of account_rep cannot also be acting in either of the roles of account_holder or teller. The policy of the bank is that an account representative, an employee of the bank, can have an account in the bank but such an individual may not simultaneously process their personal account while processing accounts of others. Likewise, because a teller has an open cash drawer that must balance when closed, an individual acting in the role of account_rep and sitting at a desk away from a teller39。s window is not permitted t