1. Web Services for Semantic Interoperability and Integration
Tim Finin
University of Maryland, Baltimore County
Dagstuhl, 20 September 2004
Joint work with many colleagues and students. 
This work was partially supported by DARPA contract F , NSF grants CCR and IIS and grants from IBM, Fujitsu and HP.

2. 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

3. 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

4. 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 …

5. 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

6. 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

7. 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

8. 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

9. 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="
<foaf:currentProject rdf:resource=" "/>
<sws:policyEnforced rdf:resource="&mary;ConfidentalityPolicy"/>
</foaf:Person>
</rdf:RDF>

10. <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>

11. 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

12. 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 =
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 = "
<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 = var1 =

13. 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.

14. Swoogle: Google for SWDs
Current Status
~190K SW documents
~1% ontologies
~33M triples
~60K classes
~50K properties
~5M values
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.

16. 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.

17. 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