Web Services for Semantic Interoperability and Integration Tim Finin University of Maryland, Baltimore County Dagstuhl, 20 September 2004 http://ebiquity.umbc.edu/v2.1/event/html/id/??/ Joint work with many colleagues and students.  http://creativecommons.org/licenses/by-nc-sa/2.0/ This work was partially supported by DARPA contract F30602-97-1-0215, NSF grants CCR007080 and IIS9875433 and grants from IBM, Fujitsu and HP.

Overview The question What role will web services play in support of semantic interoperability and integration (SII) ? My answer Illustration using two examples drawn from our work

My Answer (1) Agents fill many useful roles for SII (2) On the web, web services play the role of agents (3) The web is consuming all IT (4) Therefore web services will replace agents in systems doing SII

Agents are useful for SSI Agents are <insert your favorite definition here> Agent roles for SII include Discovery of ontologies, terms (e.g., class, property), and individuals Translation services Dynamic computing alignments and matches Meaning negotiation Reasoning services …

web services  agents On the web, there’s pressure to push all programs behind web service APIs It doesn’t make much difference if agents communicate via KQML+KIF, FIPA, or OWL+web services We want to be at a level of abstraction involving beliefs, desires, intentions, plans, goals, etc. SO, if the price of admission is to use SOAP and WSDL, we’ll pay it

The Web Is like the Blob, consuming all in it’s path Resistance is futile More seriously… it promotes sharing, building on other’s content, offering your content for building upon, decentralization, community development and evolution, common identifiers (URIs), has a working infrastructure, etc. These are significant advantages

Example: Security and Trust for Semantic Web Services Semantic web services are web services described using OWL-S Policy-based security infrastructure Advantages of using policies: Expressive -- can be over descriptions of requester, service & context Authorization: Rules for access control Privacy: Rules for protecting information Confidentiality: Cryptographic characteristics of information exchanged Policies + Semantic Web Services

Example Mary is looking for a reservation service Functional service requirements foaf identity description Confidentiality policy BravoAir is a reservation service OWL-S description Authorization policy (e.g., Only users belonging to the same project as John can access the service) Privacy policy The CMU matchmaker is an agent that finds and recommends services

Mary <!-- Mary's FOAF description --> <foaf:Person rdf:ID="mary"> <foaf:name>Mary Smith</foaf:name> <foaf:title>Ms</foaf:title> <foaf:firstName>Mary</foaf:firstName> <foaf:surname>Smith</foaf:surname> <foaf:homepage rdf:resource="http://www.somewebsite.com/marysmith.html"/> <foaf:currentProject rdf:resource=" http://www.somewebsite.com/SWS-Project.rdf "/> <sws:policyEnforced rdf:resource="&mary;ConfidentalityPolicy"/> </foaf:Person> </rdf:RDF>

<entity:Variable rdf:about="&bravo-policy;var1"/> <constraint:SimpleConstraint rdf:about="&bravo-policy;GetJohnProject" constraint:subject="&john;John" constraint:predicate="&foaf;currentProject" constraint:object="&bravo-policy;var2"/> rdf:about="&bravo-policy;SameProjectAsJohn" constraint:subject="&bravo-policy;var1" <!-- constraints combined --> <constraint:And rdf:about="&bravo-policy;AndCondition1" constraint:first="&bravo-policy;GetJohnProject" constraint:second="&bravo-policy;SameProjectAsJohn"/> Bravo Policy <deontic:Right rdf:about="&bravo-policy;AccessRight"> <deontic:actor rdf:resource="&bravo-policy;var1"/> <deontic:action rdf:resource="&bravo-service;BravoAir_ReservationAgent"/> <deontic:constraint rdf:resource="&bravo-policy;AndCondition1"/> </deontic:Right> ……… <rdf:Description rdf:about="&bravo-service;BravoAir_ReservationAgent"> <sws:policyEnforced rdf:resource="&bravo-policy;AuthPolicy"/> </rdf:Description>

How it works Matchmaker and Reasoner BravoAir Web service Mary URL to foaf desc + query request <sws:policyEnforced rdf:resource = "&bravo-policy;AuthPolicy"/> Bravo Service OWL-S Desc

How it works Mary BravoAir Web service Mary’s query = Bravo Service ? YES Extract Bravo’s policy <deontic:Right rdf:about="&bravo-policy;AccessRight"> <deontic:actor rdf:resource="&bravo-policy;var1"/> <deontic:action rdf:resource="&bravo-service;BravoAir_ReservationAgent"/> <deontic:constraint rdf:resource="&bravo-policy;AndCondition1"/> </deontic:Right> <policy:Granting rdf:about="&bravo-policy;AuthGranting"> <policy:to rdf:resource="&bravo-policy;var1"/> <policy:deontic rdf:resource="&bravo-policy;AccessRight"/> </policy:Granting> <sws:AuthorizationPolicy rdf:about="&bravo-policy;AuthPolicy"> <policy:grants rdf:resource="&bravo-policy;AuthGranting"/> </sws:AuthorizationPolicy> <rdf:Description rdf:about="&bravo-service;BravoAir_ReservationAgent"> <sws:policyEnforced rdf:resource="&bravo-policy;AuthPolicy"/> </rdf:Description> Does Mary meets Bravo’s policy ? <constraint:SimpleConstraint rdf:about = "&bravo-policy;GetJohnProject” constraint:subject="&john;John" constraint:predicate="&foaf;currentProject" constraint:object="&bravo-policy;var2"/> var2 = http://www.somewebsite.com/SWS-Project.rdf Authorization enforcement complete Mary BravoAir Web service The matchmaker first finds all those web services that match Mary’s functional description. In this case, it is only Bravo Service. The matchmaker then extracts Bravo’s authorization policy. It reasons over the authorization policy and Mary’s description to verify that the policy is met. As Mary is in the same project as John, she meets the constraints of the policy. After this the matchmaker reasons over Mary’s policy in a similar fashion. <foaf:currentProject rdf:resource = "http://www.somewebsite.com/SWS-Project.rdf"/> <constraint:SimpleConstraint rdf:about="&bravo-policy;SameProjectAsJohn" constraint:subject="&bravo-policy;var1" constraint:predicate="&foaf;currentProject" constraint:object="&bravo-policy;var2"/> Is the constraint true when var2 = http://www.somewebsite.com/SWS-Project.rdf var1 = http://www.cs.umbc.edu/~lkagal1/rei/examples/sws-sec/MaryProfile.rdf

Google has made us smarter Google has made people smarter Software agents need something similar to maximize their use of information on the semantic web.

Swoogle: Google for SWDs Current Status ~190K SW documents ~1% ontologies ~33M triples ~60K classes ~50K properties ~5M values http://swoogle.umbc.edu/ Swoogle may provide the corpus of ontologies and data that use them desired by Natasha e.g., answering queries like: Find all documents that map between O1 and O2 What classes are owl:sameAs C What values are used for properties P1 and P2? Find all OWL-S service instances Swoogle is a crawler based search & retrieval system for semantic web documents. It discovers them, builds a DB of metadata & relations, stores them in a triple store and their source in an IR system.

Example policies Authorization Privacy/Confidentiality Policy 1: Stock service not accessible after market closes Policy 2: Only LAIT lab members who are Ph.D. students can use the LAIT lab laser printer Privacy/Confidentiality Policy 3: Do not disclose my my SSN Policy 4: Do not disclose my home address or facts from which it could be easily discovered Policy 5: Do not use a service that doesn’t encrypt all input/output Policy 6: Use only those services that required an SSN if it is encrypted Privacy policies and confidentiality policies are very closely related. We currently view privacy policies as restrictions over the input and output of web services. For example, a requester may not want to use a service that asks for his SSN . A more interesting example is when a requester does not want his telephone number to be disclosed. In this case, the reasoner should be able to figure out that given the name and address it is possible to find the user’s telephone number. So the reasoner should restrict access to those services that use the name and address as well as those that use the telephone number directly. This is part of our future work. Confidentiality policies describe the cryptographic protocols required for the input and output of the service.

Swoogle2 Architecture SWOOGLE 2 service analysis digest discovery Human users Swoogle Search Ontology Dictionary Swoogle Statistics Web Server service Web Service Intelligent Agents IR analyzer SWD analyzer analysis The updated version SWD Cache SWD Metadata digest SWD Reader Candidate URLs The Web discovery Web Crawlers