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 Theaters, Restaurants – Businesses (Non-Geospatial data) Miles – Distance Unit 75080, Richardson – Geo References Cinemark Movies 10 Radisson Hotel Dallas North- Richardson

Semantic Access Control Traditional Access Control Traditional Access Control Semantic Web Semantic Access Control

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

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

Generation of Semantic enabled profile for Geospatial Query Query Profile MilesZipCode Theaters Domain Ontology (Snapshot)Generated OWL-S Semantic Profile

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

Geospatial Service Invocation -OWL-S grounding -WSDL Grounding -Service Invocation through AXIS GetTheater Process MilesZipCode Theaters GetTheater Atomic Process

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

DAGIS for Complex Queries 1. Query Profile 2. Service Discovery 3. Compose Selection 4. Construct Sequence 5.Return Dynamic Service URI DAGIS Composer DAGIS Composer Match- Maker Match- Maker DAGIS Agent DAGIS Agent Client Composer Sequencer Composer Sequencer Find Movie Theaters within 30 Miles from Richardson, TX TX Zipcode Finder Zipcode Finder Theater Process Theater Process Richardson 30 Miles Theaters

DAGIS Query Interface

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.

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 Resources Subjects Actions Condition Policy Set

Geo-WS Security: Architecture Client DAGISDAGIS DAGISDAGIS Geospatial Semantic WS Provider Enforcement Module Decision Module Authorization Module Semantic-enabled Policy DB Web Service Client SideWeb Service Provider Side

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)

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

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

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