From XML to DAML

1
From XML to DAML giving meaning to the World
Wide Web

• Katia Sycara
• The Robotics Institute
• email katia_at_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
• lt?xml version1.0 standaloneno?gt
• lt!DOCTYPE SoftAgentsPubs SYSTEM bib.dtdgt
• lt!- Here begins the XML data --gt
• ltSoftAgentsPubs xmlnsSoftAgentshttp//www.soft
  agents.orggt
• ltSoftAgentsJournalgtAI Magazinelt/SoftAgentsJourn
  algt
• ltSoftAgentsTitlegtMultiAgent Systemslt/SoftAgents
  Titlegt
• ltSoftAgentsAuthorgt
• ltSoftAgentsFirstNamegtKatialt/SoftAgentsFirstNa
  megt
• ltSoftAgentsSurnamegtSycaralt/SoftAgentsSurnamegt
  
• lt/SoftAgentsAuthorgt
• ltSoftAgentsYeargt1998lt/SoftAgentsYeargt
• lt/SoftAgentsPubsgt

5
DTD Example

• Describes the rules for defining bibliographic
  entries
• lt!- DTD Example for SoftAgents Bib Entries--gt
• ltELEMENT SoftAgentsPubs (SoftAgentsJournal,
• SoftAgentsTitle, SoftAgentsAuthor,
  SoftAgentsYear)gt
• ltELEMENT SoftAgentsJournal (PCDATA)gt
• ltELEMENT SoftAgentsTitle (PCDATA)gt
• ltELEMENT SoftAgentsAuthor (SoftAgentsFirstName,
  SoftAgentsSurname)gt
• ltELEMENT SoftAgentsFirstName (PCDATA)gt
• ltELEMENT SoftAgentsSurName (PCDATA)gt

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 sources 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