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Computational Policies in a Need to Share Environment Tim Finin University of Maryland, Baltimore County Sem. Grail workshop, Redmond WA, 21 June 2007
Introduction • Comments on the role of and requirements for computational policies in today’s environment – Web, 9/11, pervasive computing, … • Ideas in development in collaboration with colleagues from UT Dallas, GMU, and MIT
Background • We’ve been working on computational policies since about 1999 – Started with XML encoded horn clauses for supply chain mgmt & pervasive computing • Moved policy research to the Semantic Web in ~2002 – Lalana Kagal developed Rei in her dissertation • Applications have varied – Also enhanced P 3 P, service matching and selection, collaborative teams, RDF store access, and distributed router configuration.
Policy-based Automated Wide-Area Network Configuration and Management Goal: self configuring network routers running in a coalition environment demonstrating constraints on border gateway protocol
General approach • A computational policy describes a system’s actions or behavior • “Describes” can be – Specifies: whenever X, do Y – Constrains: doing X is permitted – Advises: whenever X, doing Y is preferred to doing Z • Public policies and common policies foster interoperability and cooperation
Some lessons learned • Most of the work in developing a policy is in developing the domain ontology – Often the constraints are simple, e. g. , “For faculty use only” • Sharing policies means sharing domain models – The Semantic Web offers a sound and practical approach for shared domain models
Some lessons learned • Several approaches to encoded the rules or constraints part of policies – Descriptions of permitted, forbidden and obliged classes of actions (KAOS) – Using rule extensions to RDF (Rei, Rein) • Some approaches are problematic – E. g. , uncertainty, probabilities, defaults • But OWL can do the heavy lifting in reasoning about the terms – Is Mary a full-time faculty member from a highereducational institution? What’s the evidence?
New Requirements • 9/11 and related events illustrated problems in how sensitive information is managed • Managing information and services on the Web with appropriate security and privacy and simplicity is increasingly important and challenging • Autonomous devices like mobile phones, routers and medical equipment need access too.
Need to Know, Need to Share • Traditional information security frameworks are based on “need to know” Unless you can prove that you have a prearranged right to this information, you can’t have it • The 9/11 commission recommended moving from this to “need to share” I think this information may be important for you to accomplish your mission and would like to share it with you
Need to Know, Need to Share • Traditional information security frameworks are based on “need to know” Unless you can prove that you have a prearranged right to access this information, you can’t have it • The 9/11 commission recommended moving from this to “need to share” I think this information may be important for you to accomplish your mission and would like to share it with you
Just a slogan? • For “need to share” to be more than just a political slogan, we need to understand what it might mean technically • … and to explore its feasibility and desirability • … and the risks and benefits
Required Capabilities • • Semantic Interoperability Unknown principals Context Speech acts and negotiation Adjustable privacy Usage control, enforcement, accountability Explanations and provenance Ramifications
Semantic Interoperability • Having a shared policy requires that the parties agree on – The semantics of the policy language (e. g. , is everything not explicitly forbidden allowed? ) – The semantics of the domain ontology (e. g. , who’s a faculty member? ) • The Semantic Web is a big win here.
Unknown Principles • Standard access control is based on authentication – I have a list of who can do what. Just prove to me which of these people you are • In open environments (Web, pervasive computing) this won’t work • We can control access based on their (provable) attributes – Prove you’re a current UMBC student to use the printer
Context • What’s forbidden in a normal situation may be allowed in a life-threatening emergency • Context descriptions (e. g. , tags) can identify the current situation • Policy rules can be conditioned by context – E. g. , as guards on rules or by enabling/ disabling policy modules
Adjustable privacy • One way to enforce privacy is to not divulge information • Another is to provide general answers • Where’s John? – [47. 670412403362256, -122. 12013959884644] – In Redmond – In Washington state – On travel • Policies can control the granularity of answers given to different queries
Usage control and accountability • Enforcing policies can be a difficult issue in open, distributed systems • MIT’s policy aware approach is exploring accountability for use – Policy violations can be detected in logs • There’s lots more to usage constraints – E. g. , DRM policies constrain how often you can perform certain operations on an object • Systems need to reason about there own behavior as well as that of others
Explanations and provenance • Explaining why a policy decision holds or doesn’t hold can be important – Explaining why a constraint does not hold continues to be a difficult task • The explanation may involve provenance, citing the source for the facts and policy constraints used
Utility and Ramifications • In some environments, the utility of data may be a factor in whether to share or not – This requires reasoning about the requestor’s tasks, the data’s relevance to them and the availability of alternate data • This may also require Bayesian reasoning – What’s the likelihood that the patient might have diabetes? • In general, a system might reason about the risks and benefits of sharing vs. . not sharing the data
Planned Architecture SPARQL Utility Reasoner Policy Engine OWL Reasoner OWL Domain Ontology Policy Ontology Util Ont RDF Policy Rules Instance Data Bayes Ont
Conclusion • Managing information in open, distributed environments with appropriate security and privacy is increasingly important • Computational policies can help • Semantic Web technologies offer a way to share common policy concepts, policies, and domain models • Other representation and reasoning components will be needed for many application domains.
http: //ebiquity. umbc. edu/