6.3.2 Architectural Changes

Figure: Architectural overview of the metapolicy enhanced management system

A Metapolicy Service Mobile Agent is added to the already existing agents, as shown in figure . Like the existing agents, it uses the CORBA environment, e.g. for accessing services from other CORBA components, and for event communication. It also uses the Constraint Interpreter, but this is not depicted in the figure.

The Metapolicy Supporting Service is used to store the states which are not saved by the objects themselves. This is accomplished by active metapolicies which invoke methods of the Metapolicy Supporting Service for storing and deleting states variables. The states are stored in the Object State Database.

In addition to this, the context of actions before their execution is stored by the Metapolicy Supporting Service as an action event in the Action Event Database. The changes made enable the system to control the enforcement process of policies.

Passive policies are not yet supported by the NoCScontrol system. For this reason, they are directly realised by the Metapolicy Service Mobile Agent. It provides functionality to store, retrieve, add, and save them. They are stored in the Metapolicy Database. Decisions governed by passive metapolicies are taken by the Metapolicy Supporting Service with the help of the Constraint Interpreter of the NoCScontrol system.