{"id":346,"date":"2018-11-06T00:57:02","date_gmt":"2018-11-06T00:57:02","guid":{"rendered":"http:\/\/se.kaist.ac.kr\/starlab\/?page_id=346"},"modified":"2018-12-09T14:31:24","modified_gmt":"2018-12-09T14:31:24","slug":"3-policy-specification-for-sos","status":"publish","type":"page","link":"https:\/\/se.kaist.ac.kr\/starlab\/studies\/study-1-sos-and-environment-modeling\/3-policy-specification-for-sos\/","title":{"rendered":"3) Policy Specification for SoS"},"content":{"rendered":"

Background<\/strong><\/h4>\n

A policy is described as an allowed envelop of entities’ actions, in that it defines behavior that is both permitted and required from individual entities in order to be able to operate in a given environment. We consider this definition of a policy throughout our discussion as it embodies core essence of other definitions.<\/p>\n

The policy discussed in this study is not merely about granting or denying access to a resource, like conventional definition. It is also different from security policy that maps onto various mechanisms for access control implementation. Conveying conditions on an interaction between two Web Service end-points, like WS policy, is not also the concern of collaboration policy presented in this work. Existing policy definitions consider the owner\u2019s perspective, for example, clients who want to use a resource should respect and fulfill the owner\u2019s requirements. In these three representative cases of the usual use of a policy, resource ownership and access to resources are central points. Collaboration policy is concerned about governing and guiding actions of interacting components towards achieving a common goal. Our policy (i.e., SoS collaboration policy) fulfills this intent by influencing the behavior of interacting components.<\/p>\n

Figure: SoS policy and constructing elements<\/em><\/p>\n

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Overall Approach\/Method<\/strong><\/h4>\n

Our approach to define collaboration policy for system of systems is a hybrid one, in that it combines both top-down and bottom-up approach. First of all, we identified collaboration policy constructing elements. The identification process mainly considers concepts that can be used to capture the required and\/or permitted behavior of constituent systems. For this purpose, we analyzed well-recognized characteristics and classification of system of systems. Unlike conventional systems, constituent systems composing SoS are determined to constitute an SoS based on SoS’s desired capabilities. In other words, SoS policy rules need to be derived from SoS’s desired capabilities as it is not possible to assume all specific constituent systems before an environment that exhibit the SoS\u2019s characteristics develops. However, the top-down approach need to be supported by systematic approximation of possible constituent systems capabilities. The bottom-up approach extrapolates constituent systems capabilities based on the SoS\u2019s desired capabilities. To accomplish this, we considered five constructs of collaboration policy that will help to extract capabilities of constituent systems. The constructs includes Environment, Roles, Belongingness, Constraint, and Dedication. This does not imply a need for new capabilities of constituent systems to constitute SoS. It is all about harnessing existing constituent systems’ capabilities for a new environment.<\/p>\n

In this paper we discuss how the SoS’s goal can be decomposed into policy rules with minimal assumption of constituent systems’ capabilities. Goals can be decomposed into rules using goal decomposition techniques. Rules can be defined as implementation or action oriented description of a goal. Rules are the least granularity of goal decomposition with regard to policy. Rules show only what the constituent systems should do. We used the concept of a role to represent a set of rules. Roles are a set of rights and duties associated to some specific task. The figure shown below, the top-down view shows the goal decomposition process into action-oriented goals and the extraction of desired capabilities to achieve the SoS level goal. The bottom-up blurred part represents the extrapolation process by analyzing essential characteristics of SoS and approximating the behaviors expected to be exhibited by constituent systems.<\/p>\n

Figure: Collaboration policy formulation process<\/em><\/p>\n

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Results<\/strong><\/h4>\n

(1) SoS Collaboration Policy Conceptual Model<\/p>\n

Figure: SoS collaboration policy conceptual model<\/em><\/p>\n

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(2) SoS Collaboration Policy Constructs<\/p>\n

Constructs of a collaboration policy are major components by which collaboration policy can be justified and constructed based on their relationships. We used Maier and Boardman’s SoS characteristics to identify and explain the proposed policy model constructs. It is important to note that some SoS characteristics represent purposes of the collaboration policy, for example, emergent behavior and evolutionary development. These two SoS characteristics cannot be a policy construct since they represent SoS collaboration policy purposes.<\/p>\n