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Trip Report WWW2002 |
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Trip Report WWW2002 |
one possible definition of the term "Web service": a web service is an autonomous piece of software uniquely identified by an URI that can interact with peer web services via messages using WWW specific standards and protocols, such as HTTP, XML or SOAP.
example: on-line travel agent service
service providers (credit card companies, airlines, hotels, car rental agents etc.) subscribe their web services to the travel agent's web server. customers request one or more services from the travel agent - the travel agent responds with the best possible offer based on the services provided by the service providers.
XL: an XML programming language for web service specification and composition:
today Web services are implemented using J2EE, .NET, SAP etc. and require usually translators between the various layers (data, application, messaging). these translators have a negative impact on performance.
requirements for a new programming language for web services include:
- should support a unique data model (XML)
- should be expressive enough to describe the logic of most Web services
- should coexist with W3C standards
- should be an extension of Xquery
- should provide native support for web services
XML standards are not enough for a web service specification language, but provide excellent building blocks. Xquery needed to be extended to make up a programming language with statements, loops, statement combinators etc. operations have implicit input and output in XML.
reference: see proceedings on CDrom
simulation, verification and automated composition of web services:
DAML-S provides semantic markup of the content and the capabilities of Web services. based on atomic and composite processes which provide sequences, conditions and synchronization.
reference: www.daml.org
semantic Web support for the business-to-business e-commerce lifecycle:
the lifecycle of a B2B process basically consists of the following three steps:
- matchmaking
- negotiation/contract information
- automated fulfillment
standardized message content and message protocols are fundamental for Web services. DAML+OIL may serve as a starting point for the design and the implementation of the future Web ontology language.
reference: www.daml.org
3 working groups supervised by the Web services coordination group:
- Web services architecture working group
- XML protocol working group
- Web services description working group
Web services architecture working group:
- started january 2002
- the Web services architecture requirements working draft covers the following topics:
- interoperability
- reliability
- Web-friendly (consistent with the existing Web, uses XML, aligned with semantic Web)
- security (authentication, authorization, confidentiality, data integrity, privacy protection)
- scalability and extensibility (simple, modular, extensible)
- set of team goals for the working group (july 2002: more complete and stable requirements document; october 2002: first recommendations)
- there is also a usage scenarios working draft
XML protocol working group (XMLP):
- started september 2000
- chartered to provide:
- 1) an envelope for encapsulating XML data
- a serialization based on XML schema
- an instance of a transport mechanism, namely HTTP
- a convention for representing RPC in the envelope
- achieved in the following documents:
- SOAP 1.2 part 0: primer
- SOAP 1.2 part 1: messaging framework (required):
- processing model
- envelope
- protocol binding framework
- SOAP 1.2 part 2: adjuncts (optional):
- data model
- encoding
- RPC convention
- binding and feature description convention
- message exchange pattern (MEP)
- HTTP binding
- other documents:
- SOAP 1.2 test collection
- SOAP binding to email
- "Application/soap+xml" Internet draft
- attachment feature
Web services description working group:
- started january 2002
- goal: design a description language based on the submission WSDL 1.1 reason: need for a standard format for describing Web services:
- URI
- messages accepted and generated
- access protocol
- message encoding
- standard format based on XML
- first working draft of description language in june 2002
- the working group will also provide a primer, a test suite and a mapping to RDF
XML security:
there is a requirement to ensure the integrity (via signature) and confidentiality (via encryption) of parts of XML documents.
main goal: describe how to use XML to represent a digitally encrypted Web resource including XML and portions thereof.
the semantic web is the logical extension of the current web that will allow you to find, share and combine information more easily. the current web is ok for humans, but difficult for machine processing. the semantic web relates objects in a more descriptive way than just links.
RDF architecture:
- Resource Description Framework
- a data model
- a representation of metadata
- an XML language
- RDF schema for defining vocabularies
- the foundation of the semantic Web
the RDF working group is chartered to:
- fix, clarify and improve the RDF specifications
- complete the specifications of the RDF schema
reference: www.w3.org/TR/rdf-primer/
Web ontology:
- started november 2001
- Web Ontology Language (OWL)
semantic Web advanced development:
- demonstrate the feasibility and utility of the semantic web concepts
- develop components that can form the basis for widely deployed semantic web infrastructure
- explore leading edge issues necessary for semantic web but not ready for deployment
reference: www.w3.org/2001/sw/
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