Requirements of Role - based Access Control forCollaborative

In many collaborative systems, users can trigger the execution of commands in a process owned by another user. Unless the access rights of such processes are limited, any user in the collaboration can: (1) gain access to another's private les; (2) execute applications on another user's behalf; or (3) read public system les, such as the password le, on another user's machine. However, some applications require limited sharing of private les, so it may be desirable to grant access to these les for a speciic purpose. RBAC models can be used to limit the access rights of processes, but current implementations do not enable users to exibly control the access rights of a process at runtime. We deene a discretionary access control model that enables principals to exibly control the access rights of a collaborative process. We then specify the requirements of role-based access control models necessary to implement this discretionary access control model.