6.3.5.2.2 Methods

• A public method PolicyFactoryOperation is added to the interface specification setOperPolDescription. This was done due to limited functionality which only allows creating and deleting policies. This method sets a new policy description in PDL within an existing policy object. Both the policy object identifier and the new description, are given to the method as a parameter. Successful execution returns true otherwise false. In case of successful execution, the new method calls the notify_MPAgent method to notify its execution before it returns. It is also used by the active metapolicy example. With this new method, the notification mechanism incorporated by the notify_MPAgent can be tested without touching existing methods.

• The private method notify_MPAgent gets the name of a method and its parameters typed as strings and creates an execution event. This event is a structured event as described in [Radi 98]. It sends the event to the Metapolicy Service Mobile Agent.

  The use of parameters typed as strings is not a restriction at the moment and is used for convenience. With changes to the system in the future, a more generic mechanism must be incorporated allowing a generic notification of (internal) state changes. Without any changes of each method, the tie mechanism [Vis 97a,Radi 98] could be used for sending the event. This possibility is not used here because the tie mechanism is only used to simulate multiple inheritance in Java. Therefore, it is supposed to be transparent. Adding functionality to the created tie classes violates this assumption.

• The push method is implemented for the use of the two event channels, PolicyEventChannel and MPAgentChannel. The use of the two event channels is terminated by the method disconnect_push_supplier and disconnect_push_customer.