A successful policy negotiation scheme for Policy-Based Management (PBM) has been implemented. Policy negotiation is the process of determining the “best” communication policy that all of the parties involved can agree on. Specifically, the problem is how to reconcile the various (and possibly conflicting) communication protocols used by different divisions. The solution must use protocols available to all parties involved, and should attempt to do so in the best way possible. Which protocols are commonly available, and what the definition of “best” is will be dependent on the parties involved and their individual communications priorities.
This method is based on defeasible policy composition (DPC), a new approach for finding conflicts and resolving priorities between rules. A formulation and scenario for how cross-domain interoperability can be achieved have been developed based on a negotiation mechanism between different parties (domains) so that all parties can agree on procedures for interacting with each other. An implementation of this methodology has been developed in the form of an executable code and corresponding GUI interface.
The network management and Web communication software used by the different organizations presents a stumbling block. Many of the tools used by the various divisions do not have the ability to communicate network management data with each other. At best, this means that manual human intervention into the communication protocols used at various network routers and endpoints is required. This process is tedious, error-prone, and slow.
The present methods have inherent inefficiency and are not fully automatic, which heavily restricts their practical applications. The new method is based on an efficient algorithm. The new engine utilizes defeasible logic to describe communication policy constraints and priorities. Defeasible logic (see figure) is nonmonotonic, and contains three different types of rules: strict rules, which are strict “if/then” statements; defeasible rules that are “if this, then probably that” statements; and defeater rules that contradict the outcomes of defeasible rules.
The policy negotiation program reads in two files specifying the policies that the user wishes to combine, and outputs a single file describing the means of communication that satisfy both input policies, if any can be found.
To implement this method, a tool called DPC (Defeasible Policy Composition) was developed. To maintain that efficiency in the DPC tool, the data structures for the individual terms of each constraint are joined in linked-list fashion to their constraints and to a parent object representing each term. This can be visualized as a linked grid, where the heads of each column are the terms, the heads of each row are the rule names, and the body of the grid is the references to the terms that make up those rules. Each term reference is linked to its neighbors in the grid, which allows the algorithm to quickly and efficiently search through, add, and delete rows, terms, and individual term references.
This work was done by Farrokh Vatan and Edward T. Chow of Caltech for NASA’s Jet Propulsion Laboratory.
This Brief includes a Technical Support Package (TSP).
Policy-Based Negotiation Engine for Cross-Domain Interoperability
(reference NPO-48399) is currently available for download from the TSP library.
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