1. From XML to DAML – giving meaning to the World Wide Web Katia Sycara The Robotics Institute email: katia@cs.cmu.edu www.cs.cmu.edu/~softagents

2. Brief History of Markup Languages Standard Generalisaed Markup Language (SGML) –Markup for electronic documents, used by publishers. –Described a document in terms of its structure, not in terms of formatting. –Syntax designed to be both Human and Machine readable. HyperText Markup Language (HTML) –Markup for describing Web Pages. –Development of tags for describing format, at the expense of describing document structure. eXtensible Markup Language (XML) –Compact version of SGML tailored for Web delivery –Retains markup for document structure –Additional schemes for formatting (XSL), document linking (XLink), Framework Metadatas (RDF), and others Darpa Agent Markup Language (DAML) –The future?

3. XML Differs from HTML in that it describes information, not presentation –Separates the user interface from the data. –Structure is defined (and hence machine readable), not implied by layout (as in HTML). Self-Describing data format –Each document contains a set of rules (Data Type Definitions – DTDs) describing the data format. –Rules can be user defined, or conform to some industry standard for data exchange/conformity XML uses –Data Interchange format –Describing Web Data

4. XML Example XML Document describing a bibliographic reference AI Magazine MultiAgent Systems Katia Sycara 1998

5. DTD Example Describes the rules for defining bibliographic entries <ELEMENT SoftAgents:Pubs (SoftAgents:Journal, SoftAgents:Title, SoftAgents:Author, SoftAgents:Year)>

6. XML Schemes XSL –Specification for the presentation of a class of XML documents. –Stylesheets describe formatting, both physical (e.g. Italics), layout (right justified paragraphs) and describing contents lists, indexes etc. Xlink –Specification for describing and linking resources to web pages. –Can describe simple hypertext links (eg HREF in HTML), as well as more sophisticated links. RDF – Resource Description Framework –Describes relationships between entities –Uses triples – chair has value red for property/attribute color

7. Beyond XML Web is the biggest knowledge base that ever existed. –Current data is Human but not Machine understandable. –Heterogeneous, geographically distributed information, no management, currently only search engines based on keyword searches; no classification metadata. –Open, new information sources get added without formal control and whose identity is unknown at the time of application development. XML describes data, but not relationships between data. Agents are becoming ubiquitous on the Web & within E-Commerce –Many agent-based services available, but are designed for human consumption –Agents can locate services, but interaction with new services needs to be autonomous (i.e. agents should understand each other without human assistance)

8. DAML – DARPA Agent Markup Language DAML will create the next major generation of Web/Internet technology...  The first generation, the Internet, created largely by DARPA, enabled disparate machines to exchange data.  The second generation, the World Wide Web, enabled a wide range of new applications on top of the growing Internet. The Web made a huge amount of information available, in human- readable form, allowing a revolution in new applications, environments, and b2c e-commerce.  The next generation of the net is an “agent-enabled” resource (the “Semantic Web”) which makes a huge amount of information available in machine-readable form creating a revolution in new applications, environments, and b2b e-commerce.

9. Agent Based Approach Universal presence of agents: –Each is functionally specific. –Acts as a universal interface to the diverse Web entities (e.g. documents, databases, sensors, programs). An agent that wraps a Web resource: –Advertises the capability of the information source; this provides a mapping from the domain model to the queries the source can answer –Maps the source’s capability to the native query language of the source –Executes requests to the underlying source (one shot and persistent) Specific Agents support middle-agent services: –Middle agents for service discovery/location –Ontology Agents for determining semantic relationships between entities