DAML Ontologies for Agent-Enabled Web Services SheilaAMcilraith Department of Computer Science Knowledge Systems Laboratory (KSL Stanford University DAML Ontologies for Agent-Enabled Web Services CFA8D4A2C65A97BF6603AAE3B6ADA512 GROBID - A machine learning software for extracting information from scholarly documents

Problem: The Web is not computer-interpretable Precludes easy automation of tasks

We are developing:

• semantic markup to enable automation by making service capabilities, user constraints & procedures computer-interpretable & use-apparent.

• agent technology that exploits semantic markup to support automated Web service discovery, execution, composition and interoperation.
Background

The Web is evolving from a provider of documents and images … Background … to a provider of services Goal Automation of:

• Web service discovery

Find me an airline service that offers flights to Tuktoyuktuk

RDFS (RDF Schema)

DAML+OIL (Ontology) [Fensel+others, 2000] DAML-SL Service described as processes (sequence, if-then-else, while, iteration, …) of

• inputs & outputs (function metaphor)

• preconditions & effects (action metaphor)

Semantic Markup of Web Services

Each Web site provides a set of services

• information providing (e.g., flight schedules, camera views) &/or

• world-altering (e.g., flight booking, home temp. adjustment)

DAML-enabled web pages

Web service sites are annotated with DAML markup.

Function/Dataflow Metaphor www.acmeair.com book flight service Input:

• confirmation no.

• ...

Output:

• failure notification

• • • • Process of Processes • • • • • • • • • • • • • • ? • • • • • • • • • • • Input & Preconditions Output & Effects • • • • • • • •
Web Services Markup Exploits Ontologies

Ontologies support sharing, reuse, succinct markup:

Collectively markup create a distributed KB of services. Situation Calculus [McCarthy,68] + Golog [Levesque et al, 97] procedural constructs:

• sequencing • if-then-else

Properties of Our System

Logical-based approach enables us to enforce and/or prove properties of our system:

-safety constraints -goal achievement -maintenance constraints Implementation of middle ground interpreter is sound & complete with respect to logical specification.

Characterization of classes of procedures that are knowledge self-sufficient. Proved properties wrt execution termination.

Extensible Markup Language) RDF (Resource Description Framework)Goal Semantic Markup: DAML-S Layered Language Development• Web service execution Buy me "Harry Potter and the Sorcerer's Stone" at www.amazon.com • Web service selection, composition and interoperation Req'd Markup: declarative advertisements Req'd Markup: declarative API (inputs & outputs) Automation of: DAML-S ** : A DARPA Agent Markup Language for Services • Web service discovery Find me an airline service that offers flights to Tuktoyuktuk • Web service execution Buy me "Harry Potter and the Sorcerer's Stone" at • Web service selection, composition and interoperation Req'd Markup: declarative API (inputs & outputs) • Pre-release of DAML-S version 0.5 scheduled for June,2001 O p p o r t u n i t y A r e a CMU, BBN, and Nokia, under the auspices of DARPA. www.amazon.com Req'd Markup: declarative advertisements I n d u s t r y e f f o r t s g r o w i n g • AI-Inspired markup language for Web services: • Developed by a coalition of researchers from Stanford, SRI, ( w e a r e i m p r o v i n g w i t h D A M L ) • well-defined semantics • ontologies support reuse, mapping, succinct markup, ... DAML-S (Services)Make the travel arrangements for my WWW10 conference Make the travel arrangements for my WWW10 conference • Watch http://www.daml.org/services/daml-s for detailsReq'd Markup: declarative use spec. (preconditions & effects) Req'd Markup: declarative use spec. (preconditions & effects) ** (initiated 02/2001 following independent research efforts)
DAML-L (Logic)XML (
Semantic Web Services
How it Works

Agent's KB is automatically constructed relative to the generic procedure and user constraints.

Deductive machinery instantiates the generic procedure wrt. constraints and world state to generate Web service requests that the agent broker executes.

Middle ground interpreter balances information gathering services with delayed execution of world-altering services. • Computer-interpretable, use-apparent, agent-enabled services.

• Ontologies facilitate construction, sharing, reuse, and composition; support succinct web site markup. • Markup not specific to particular agent implementation.

2) Agent Technology for Automated Web Service Composition:

• Theme: usability and customization • Approach: Generic procedures and customizing user constraints • Deductive machinery instantiates procedures generating web service requests that are sent to the agent broker.