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In fact, the network computers do not include explicit notion of activation since it
assumes that the assigned roles are activated as soon as the agents take the roles. We
believe that such an assumption is not adequate enough and need to be removed to
support scenarios where explicit notion of activation is required. As an example,
consider a biotechnology project community in which there is a role for cloning body
tissues and three technicians are able to take the role as shown in Fig. 8. In this case,
three technicians can be assigned to the 'cloning' role. However, this job should be
performed by a totally isolated technician because it is a very delicate job. If one
technician does perform cloning, then we should prevent accesses to cloning task
from another technician. In order to enforce that, we can specify a policy that allows
at most one user to activate the 'cloning' role at a time (dynamic maximum
cardinality constraint). Although an alternative way is to change the role assignments
every time a user wants to access the 'cloning' role.
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