Web Services at W3C and the Status of SOAP Version 1.2

Hugo Haas <[email protected]>
W3C Web Services Activity Lead

Presentation at Evolve Conference 2002, Sydney, Australia, 8 October 2002

Slides available at:
http://www.w3.org/2002/Talks/1008-hh-w3cday/

Overview

• Overview of the work at W3C
• Architecture and description work
• Focus on SOAP 1.2

History

From human to machines:

Originally

World Wide Web designed for people to share information

Early

People have been using HTML forms as interfaces to access programs (CGI programs)

More recently

Machine to machine interactions

Web service:

• Application
• For use by another application
• Accessed via the Web (URI / XML)

Standardization work

Core technologies have been worked on for a long time:

• XML: XML 1.0, XML Schema, ...
• Security foundation: digital signatures, encryption, key management
• Privacy: P3P
• Etc.

Web Services Activity: Web services technologies

Web Services Activity

• Created in January 2002
• Subsumes the XML Protocol Activity started in September 2000
• Large Activity: more than 65 Member organizations
• All the work is done in public: mailing list archives, meeting records, editors' copies
• Technologies developed under Royalty-Free terms
• Organization:

  3 Working Groups:

  • Web Services Architecture Working Group
  • XML Protocol Working Group
  • Web Services Description Working Group

  1 Coordination Group

Design of the Web Services Architecture

• Goal: define the Web services architecture
  • What are we trying to achieve with Web services?
  • What technology is needed?
  • What is the scope of each technology identified, and its relationship with the others?
• Output used to scope proposals for new Working Groups
• Work started in January 2002
• Developed by the Web Services Architecture Working Group
• 71 participants representing 48 Member organizations

Requirements of the Web services architecture

• Enable interoperability
• Reliable:
  • Well defined
  • Set of metrics, e.g. for measuring quality of service
• Clean integration in the Web
• Security and privacy
• Scalability and extensibility:
  • Modular
  • Extensible, open-ended

Integration to the World Wide Web

Need to respect the Web's architectural principals

Web is a set of resources that are:

• identified (URI)
• retrieved using certain rules (e.g. HTTP GET)
• structured (e.g. XML)

Design of Web services technologies must be done in a Web-friendly way

Status of the Web Services Architecture Working Group

Documents listed on the Working Group's page:

• Requirements for the Web services architecture: Working Draft
• Usage scenario document: Working Draft
• Architecture document: editors' copy
• Glossary: editors' copy

A language to describe Web services

Problem: I want to use your Web Service

• Where can I find it?
• What messages are accepted / generated? What syntax?
• How should they be transmitted?

Need standard format for describing Web Services

WSDL 1.1 (W3C Submission) used as a starting point

• Work started in January 2002
• Done by Web Services Description Working Group
• 49 participants representing 32 Member organizations

Status of the Web Services Description Working Group

Documents listed on the Working Group's page:

• Requirements document published:
  • Based on the XML Information Set
  • Use W3C XML Schema but allow other schema languages
  • Simple interaction between Web Services: one-way, request-response, solicit-response, and faults
  • Binding to SOAP 1.2 and HTTP/1.1
  • Extensibility and versioning
• Published a set of usage scenarios
• Published a first Working Draft of the description language:
  • Web Services Description Language (WSDL) Version 1.2
  • Web Services Description Language (WSDL) Version 1.2: Bindings

Communicating between machines

• Need for a messaging protocol allowing complex machine to machine interactions
• Information of complex type
• Extensibility is key; support for:
  • Security extensions
  • Reliability extensions
  • Caching extensions
  • Etc.

An XML-based protocol: SOAP version 1.2

• Work started in September 2000 as a result of growing interest in the use of XML in distributed applications communication
• XML Protocol Working Group: 45 participants representing 27 Member organizations
• Technical solutions proposed by the SOAP/1.1 submission evaluated

SOAP 1.2 in a nutshell

• SOAP message:
  • Envelope (XML document)
  • Composed of a header and a body

    

• Processing model
  • Sent from a sender to a receiver, possibly via intermediaries
  • Headers:
    • Can be addressed to certain intermediaries
    • Can be marked as mandatory
• Default data encoding provided, but others can be used.
• Can be transfered from one node to another any underlying protocol (e.g. HTTP): SOAP binding

SOAP 1.2 extensibility

Feature:

abstract piece of functionality typically associated with the exchange of messages between communicating SOAP nodes

Types:

• SOAP module: expressed as a header
• Provided by a binding
• Message exchange pattern (MEP)

SOAP 1.2 adjuncts

• SOAP Encoding: how to encode data, according to the SOAP Data Model
• Representation for RPC operations.
• Definition of response and request-response message exchange patterns
• Abstract model for attachments
• HTTP binding

Status of the work on SOAP version 1.2

Started from SOAP/1.1; more than 300 issues found and then solved.

Outline of the work done:

• Processing model clarification
• Based on the XML Information Set
• Support from XML Base
• Encoding based on XML Schema 1.0
• Formalization
  • SOAP Protocol Binding Framework: underlying protocol agnostic
  • Feature and MEP descriptions
  • Etc.

Specifications in Last Call.

Documents produced by the XML Protocol Working Group

Documents listed on the Working Group page:

• XML Protocol (XMLP) Requirements Document: Working Draft
• XML Protocol Usage Scenarios: Working Draft
• XML Protocol Abstract Model: Working Draft
• SOAP version 1.2, Part 0: Primer: Last Call Working Draft
• SOAP version 1.2, Part 1: Messaging Framework: Last Call Working Draft
• SOAP version 1.2, Part 2: Adjuncts: Last Call Working Draft
• SOAP 1.2 Attachment Feature: Last Call Working Draft (deadline for comments: 15 October 2002)
• SOAP Version 1.2 Specification Assertions and Test Collection: Last Call Working Draft
• SOAP Version 1.2 Email Binding: Note

Next steps

• SOAP version 1.2 to Recommendation
• Architecture:
  • continue architecture definition
  • propose new work: choreography being considered
• Description work: address issues found against WSDL 1.1, design binding to SOAP Version 1.2, develop an RDF mapping

References

This presentation: http://www.w3.org/2002/Talks/1008-hh-w3cday/

W3C Web Services Activity: http://www.w3.org/2002/ws/