Web Architecture
Addressing and Data Formats
Dan Connolly
W3C
WAPForum Meeting
February 1998
Fort Worth, TX
Overview
- Architecture
- Addressing: URIs
- Data Formats: XML
- Q&A...
Web Architecture
- Addressing: URIs
- Protocols: HTTP, ...
- Data Formats: HTML, XML, ...
notes from '91
Addressing: URIs
- Jun '94: URI spec Informational
(RFC 1630)
- Dec '94: URL Proposed Standard
(RFC 1738, 1808)
- Aug '98: Common Syntax to Draft Standard
(RFC 2396)
Addressing: Issues
- Parsing, extensibility bugs
- Maintenance of the list of URI schemes
guidelines
- Persistence (URNs, DOIs, rights management)
- Integrating TV, telephone
Addressing: Opportunities
1st class objects vs.
- overuse of POST
- MIME x-types
- mailto: misnomer
"value of the network varies with the square of the number of resources"
Data Formats
- HTML, plain text
- GIF, JPEG, ...
- Style Sheets: CSS, XSL
- XML
Format Negotiation
- In Theory: Client advertises capabilities
Server optimizes response
- In Practice: Client advertises product codes
Server kludges around bugs
Format Negotiation
- Lesson: evolution of capability list
W3C Data Format Architecture: XML
- Self-evident, self-similar structure
no tag inference
- Make HTML components usable by reference
XML: past, present, future
- Fall 1996: 1st Draft at SGML Conference
- Nov 1997: Proposed Recommendation
- Feb 1998: Recommendation
- June 1998: Continuing Work on XML
- Jan 1999: Namespaces Recommendation
XML Applications
- HTML Math (MathML)
- Synchronized Multimedia Integration Language (SMIL)
- Resource Description Framework (RDF)
- Scalable Vector Graphics (SVG)
XML Namespaces
- Address tag name collisions, ambiguity
- Namespaces are 1st class (addressable) resources
RDF
metadata infrastructure for...
- Automated contract exchange
- Web structure analysis
- Bibliographic records (Dublin Core)
- Persistence (availability guarantees, rights management)
XML Activity
- XML Schema WG
- XML Linking WG
- XML Fragments WG
- XML Syntax WG
- XML Infoset WG
XML Schemas
- Provide DTD facilities in self-similar syntax
- Provide 1st-class module facility
- Integrate with modern data stores?
- Integrate with modern software development?
XML Linking
- modularize HTML linking
- link services, annotations, ...
- bring the web into the '70s
XML Fragments
- deal with fragments out of context
- update-grams?
- packaging?
XML Syntax
XML Infoset
- make the implicit data model explicit
@@namespaces
@@XML linking and WML
@@XML profile, voyager profile