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DAGIS : Automatic Discovery of Geospatial Information Services

DAGIS : Automatic Discovery of Geospatial Information Services. Ashraful Alam Ganesh Subbiah Dr. Bhavani Thuraisingham Dr. Latifur Khan. Motivating Scenario. Query: “ Find movie theaters within 30 miles of 75080” within, near, overlap – Geospatial Operators

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DAGIS : Automatic Discovery of Geospatial Information Services

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  1. DAGIS : Automatic Discovery of Geospatial Information Services Ashraful Alam Ganesh Subbiah Dr. Bhavani Thuraisingham Dr. Latifur Khan

  2. Motivating Scenario Query: “Find movie theaters within 30 miles of 75080” within, near, overlap – Geospatial Operators Theaters, Restaurants – Businesses (Non-Geospatial data) Miles – Distance Unit 75080 , Richardson – Geo References Cinemark Movies 10 Radisson Hotel Dallas North-Richardson

  3. Semantic Access Control Traditional Access Control Semantic Web Semantic Access Control

  4. Semantic Access Control (cont.) • Shortcomings of Traditional Access Control • Proprietary systems • Lack of modularity • Changes in access control schemas break the system • Changes in data schemas break the system • Path to resources (e.g., XPATH) is clumsy //school/department/professor/personal/ssn – LONG! • Non-optimal for distributed/federation environment

  5. Query Grammar Define, Geospatial Objects as GB, Geospatial Operator as GO, Polygon Type as PT and Extension as E. Then, • <Query> :: <GB> [<GO>] [<PT>] [<E>] <GB> • <GB> :: Non-geometric Concept • <GO> :: <Operator Terminal> • <PT> :: <Polygon Terminal> • <E> :: Distance • <Operator Terminal> :: Within | Touches On | • Intersect | Between • <Polygon Terminal> :: Straight line | Circle

  6. Theaters Query Profile ZipCode Miles Generation of Semantic enabled profile for Geospatial Query Generated OWL-S Semantic Profile Domain Ontology (Snapshot)

  7. Geospatial Service Selection and Discovery • DAGIS Agent • OWL-S MX Matchmaker • Best Service Match : Functionality,QoS Degrees of Match: EXACT < PLUG-IN < SUBSUMES< SUBSUMED-BY<LOGIC BASED FAIL < NEAREST-NEIGHBOUR < FAIL

  8. Theaters GetTheater Process ZipCode Miles Geospatial Service Invocation -OWL-S grounding -WSDL Grounding -Service Invocation through AXIS GetTheater Atomic Process

  9. Service Provider - 1 1.Register/ Advertise DAGIS Matchmaker … … Service Provider - n 3.Service Discovery, Service Enactment Reasoner/ Matching Engine DAGIS Interface DAGIS Agent 2. Query DAGIS System Architecture • DAGIS Query Interface • OWL-S MatchMaker • OWL-DL Reasoner for Matchmaker • Service Providers

  10. Richardson Zipcode Finder Theater Process TX Theaters 30 Miles Client DAGIS Agent Match- Maker DAGIS Composer 1. Query Profile 2. Service Discovery 3. ComposeSelection Composer Sequencer • .Return Dynamic • Service URI 4. Construct Sequence DAGIS for Complex Queries Find Movie Theaters within 30 Miles from Richardson, TX

  11. DAGIS Query Interface

  12. Geo-WS Security • Data providers (e.g., geospatial clearinghouses, research centers) need access control on serviceable resources. • Access policies have geospatial dimension • Bob has access on Building A • Bob does NOT have access on Building B • Building A and B have overlapping area • Current access control mechanisms are static and non-modular.

  13. Geo-WS Security: Policy Components • Subjects: Software Agents or Human clients • Resources: Assets exposed through WS • Actions: Read, Write, Execute • Conditions: Additional constraints (e.g., geospatial parameters) on policy enforcement Policy Set Subjects Condition Resources Actions

  14. Geo-WS Security: Architecture D A G I S Geospatial Semantic WS Provider Client Enforcement Module Decision Module Authorization Module Semantic-enabled Policy DB Web Service Client Side Web Service Provider Side

  15. Geo-WS Security: Semantics • Policy rules are based on description logic (DL). • DL allows machine-processed deductions on policy base. • Example 1: • DL Rule: ‘Stores’ Inverse ‘Is Stored In’ • Fact: Airplane_Hanger(X) ‘stores’ Airplane(Y) • Example 2: • DL Rule: ‘Is Located In’ is Transitive. • Fact: Polygon(S) ‘Is Located In’ Polygon(V) Polygon(V) ‘Is Located In’ Polygon(T)

  16. Geo-WS Security: Inferencing Semantic-enabled Policy DB Obvious facts Deduced facts Inferencing Module Geospatial Data Store

  17. Geo-WS Security: Concrete Example • Resource := Washington, Oregon, California, West Coast • Rule:= West Coast = WA Union OR Union CA • Policy:= • Subject:= Bob • Resources:= WA, OR, CA • Action:=Read • Query: Retrieve Interstate Highway topology of West Coast

  18. Future Directions • QoS based Selection for Complex Queries • Automatic Trust Negotiation for DAGIS • Define a specification for access control semantics

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