Dr. Leo Obrst MITRE Information Semantics Information Discovery & Understanding Command & Control Center SOA, Ontologies, and the Pragmatic Web SOA e-Gov Conference October 2, 2007 MITRE, McLean VA

2 Semantic Integration Implies Semantic Composition Simple Procedure Integration & Composition Concatenation, alignment of calling Procedure with called procedure: Caller: Do_this (integer: 5, string: “sales”) Called: Do_this (integer: X, string: Y) Simple Syntactic Object Integration & Composition Alignment of embedded interface definition language statements mapping two CORBA, Javabean objects Simple Semantic Model, Knowledge Integration & Composition Unification of tree or graph structures, with reasoning, simple Semantic Web ontologies: - signifies the composition operation Complex Semantic Model, Knowledge, System Integration & Composition Unification of complex networks of graph Structures, with complex reasoning, complex Semantic Web ontologies, Semantic SOA:

3 Two Stacks of Concepts & Standards: Semantic Web Semantic Web Services Syntax: Data Structure Semantics Higher Semantics Reasoning/Proof XML XML Schema RDF/RDF Schema OWL Inference Engine Trust Security/Identity Use, Intent Pragmatic Web Intelligent Domain Services, Applications Agents, Brokers, Policies Grid & Semantic Grid Services Adapted from: Bussler, Christoph; Dieter Fensel; Alexander Maedche A Conceptual Architecture for Semantic Web Enabled Web Services. SIGMOD Record, Dec Semantics  Pragmatics

4 What’s Pragmatics? Semantics in Context: Use & Intent Context, Context Change: Meaning in Use Some meanings can only be determined in use, so really is a Semantic-Pragmatic continuum Possible Worlds Semantics: Truth wrt Context Reasoning involving speech acts –Assertion (Tell), Question (Ask) –Promise/Obligation, Commitment, Belief, Etc. –Services: Complex Process Model of Acts, Pre-/Post-Conditions Intent: What is the Purpose? –Policy: Normative, Legal, and Best Value –Ontologies & Rules to support not only Domain Semantics but Policy Semantics-Pragmatics

5 Use / Intent Semantic Web artifacts define their meaning using ontologies, fact/knowledge bases, and Semantic Web services Those semantic models and services are intended to –Represent what you mean –Be used by others in the way you meant them to be used The Pragmatic Web concerns the correct interpretation of semantic models and services in context –i.e., according to the use and intent they were created for, perhaps in a specific process/workflow model –By a human, an agent, or another Semantic Web service Policy: in many cases, you will declare a Semantic Web policy about how your Semantic Web models and services need to be interpreted and used –Like business rules and pragmas in computer programming –Coercions will be needed, but violations should be flagged – as violating the use and intent of your semantics –Policy helps stabilize the Semantic Web –Policy helps maintain your and your site’s credibility –Policy helps agents and services interpret how they should interpret your models and services

6 Potential Ontology & Semantic Web Benefits Improved discovery and understanding of data and services More agile integration and semantic interoperability of information & services Better support for intelligent, adaptive applications, services Find relevant data and services Map to different vocabularies & models used by different communities of interest Mediate, fuse, compose, and orchestrate Services Facilitate Machine-to- Machine semantic interaction Move from point-to-point integration to networked, hub-based integration Requires data provenance, identity, security, use/intent of semantics = Pragmatics Need to support thousands of autonomous participants contributing content Self-synchronizing Adaptive to changes The right stuff in the right context to the right person Dynamic Semantic- Pragmatic SOA Current tools, many standards focus on syntactic layers (equivalent of Google keyword) If we want to make data & services understandable, need ontologies and Semantic/Pragmatic Web

7 OWL-S: An Ontology for Web Services - Motivations Automatic Web Discovery –Automatic location of Web services providing a particular service & adhering to user-requested constraints Automatic Web service invocation –Execution of a Web service as a set of function calls –OWL-S provides a declarative, computer-interpretable API for executing these function calls Automatic Web service composition and interoperation –Automatic selection, composition, interoperation of Web services to perform some task, given a high-level description of a goal Automatic Web service execution monitoring –Simple & composed services will require time to execute –User may need to check status, modify behavior of agent executing service * See: OWL-S: Semantic Markup for Web Services. OWL-S 1.0. The OWL Services Coalition,

8 *OWL-S: Service Ontology’s Top-level Classes ServiceModel provides supports presents describedBy ServiceProfile ServiceGrounding What the service does: Advertisement Properties: functionality, inputs, outputs, pre- & post- conditions *Now, OWL-S. From: DAML-S: Semantic Markup for Web Services, 2003, ServiceResource How it works, how to use it: Recipe Process Model: control flow, data flow How to access, communicate with it (e.g., Transport Protocols ) Connects process model to protocols & messages in WSDL

9 *OWL-S Process Ontology ProcessModel ServiceModel subClassOf ProcessControl Process CompositeProcess expand/contract Sequence If/Then/Else Split Input output participant precondition effect... ProcessList ProcessBag RepeatUntil component *Now, OWL-S. From: DAML-S: DAML-S: Accessing Information and Services on the Web, Mark Burstein, David Martin, Sheila McIlwraith, 2001.

10 Build a House Purchase Land Get Real Estate Agent Self Handle Real Estate Obtain Zoning Variance Obtain Financing Architect Custom Design BuildHouse Find Site Expands to OR Environment Property + State Variables (changing constraint values) Get Attorney OR Get General ContractorMoveBuild Then Instantiate (with real constraints) Schedule (with schedule constraints) Execute, monitoring constraints