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6.2.3.3 State of Managed Objects

The state of objects must be observed to gather the necessary (management) information metapolicies use. Therefore, it must be clear which information is needed, how this information is collected, and how it is saved for later use.

The information needed for stating metapolicies is hard to predict. As mentioned in subsection [*], the expressiveness of a metapolicy depends on the available information in a management system. As a result of this, a certain amount of state information must be available. As in all management areas, the more and the detailed information a management system can use, the better a system can be managed.

The refinement metapolicy ``A modified policy must be reviewed, before being activated again.'' entails the ability of observing the modification of a policy. If a policy is not immediately reviewed after the observation of its modification, the status, that this policy must be reviewed, must also be saved. A very flexible approach which allows the introduction of such information in addition to the metapolicy would be helpful. With introduction of the information, a mechanism for gathering the information must be specified.

The question arises which component is responsible for the observation and where is the collected information stored? Three solutions are possible in the NoCScontrol system:

objects are responsible
In this model, the components are responsible for collecting and saving the data needed to preserve the state.

Each object saves its state in new attributes, which are accessible through an API. Every method which changes the state must also change the corresponding attributes.

This causes alteration of every component and every method in the NoCScontrol system and scales very badly. On the other hand, this adds the possibility of making every internal change externally visible.

agents are responsible
In the architecture of NoCScontrol, the objects live on agents. Therefore, the possibility exists to make the agents responsible for the objects, which live on them.

The agent monitors all of its objects and processes, saves the state changes and makes them accessible through a standard API. Information which the objects cannot save by themselves must be saved by the agent.

adding a metapolicy support agent

The tasks can be separated out to a new Metapolicy Service Mobile Agent responsible for monitoring and saving of states in the NoCScontrol system.

An approach where all components and objects send notifications of changes with the help of events has the greatest flexibility and scalability. The new metapolicy support agent would save the states whenever the metapolicies are interested.

Another advantage could be the integration of other metapolicy concerns, like the component needed for passive metapolicy support discussed in the second item on page [*]. Also the management of the policy life cycle is possible, because this new agent has a macroscopic view on the management system such as its policy and enforcement objects and supporting processes.

In the remainder of this thesis I will assume that there is a Metapolicy Service Mobile Agent present.


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Next: 6.2.3.4 Management Functionality Up: 6.2.3 Realisation of Metapolicy Previous: 6.2.3.2 Managed Objects   Contents
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