W3C Workshop on Constraints and Capabilities for Web Services

About the Workshop Format

• Presentations and discussion
• 10-15 minutes of Q&A at the end of each presentation
• Goals:
  • Understand the problem space
  • Examine proposed solutions
  • Gauge common interest in further work
  • Recommend a course of action to the W3C

Program Outline

• Today
  • Presentations: Use Cases and Requirements
  • Discussion: Problem Domain and Use Cases
  • Lunch
  • Presentations: Candidate Solutions
• Tomorrow
  • Presentations: Candidate Solutions (cont'd)
  • Lunch
  • Discussion: Candidate Solutions
  • Discussion: Conclusions and Next Steps

Workshop Logistics

• Parking
• Bathrooms
• Internet and power
• IRC - irc.w3.org:6665 #ccws
• Breaks / Lunch
• Dinner arrangements
• Scribes

Presentations: Use Cases

9:00-9:30am

Publishing Web Service Policies
British Telecommunications

9:30-10:00am

Position Paper
Layer 7 Technologies, Systinet

10:00-10:30am

Web Services and Internationalization
webMethods, Inc.

Discussion: Potential Scope

1. You must use gzip content-encoding to access this service. (constraints, configuration)
2. The service can generate text messages in English or French. (negotiation, capabilities)
3. The service can only be contacted between 8am and 6pm US/Pacific. (business-oriented)
4. The MTU of my network is 1500 bytes only. (parameter)
5. Your retry timeout must be more than 2000 milliseconds. (comparison)
6. You must not be a basic-level customer to access this service. (negation)
7. Contact me only if you have a privacy policy. (abstraction, validation)
8. You can only access this information if you agree to make changes to it freely available. (postcondition)
9. When you access this service, you may use TLS or WS-Security; but WS-Security is preferred. (preference, composition)
10. Using TLS costs $9; using WS-Security $15. (metapolicy)
11. Don't contact me unless you've been authorized/trusted by auth.example.org. (third-party coordination / delegation / choreography?)
12. The <purchaseOrder> element must contains one or more <item> elements. (WSDL / XML Schema?)
13. The next ten messages you send must be no larger than 2048 bytes. (attachment scoping)

Discussion: Scope

• What are the use cases for assertions?
• What does the framework provide?
• What is the problem domain being addressed?

Discussion: Use Cases for Assertions

• Constraints and Capabilities are?
  • "On-the-wire" configuration and/or business policy?
  • Associated with servers, clients, intermediaries? ?
  • Scoped to messages, interactions? ?
  • About preconditions, postconditions?
  • Assertions about artefacts or behaviours?
  • Can assertions have relationships? E.g., abstract and concrete?
  • Should an application still be able to function without it?

What Does the Framework Provide?

• Negotiation
• Comparison ( < > = …)
• Negation
• Client / server configuration
• Validation
• versioning, policy lifetime
• Preferences
• Metapolicy (e.g., cost, quality of service)
• Delegation, provenance
• Combination, merging
• Attachment flexibility
• Attachment scoping
• Processing Model

Discussion: Problem Domain

• Constraint and Capabilities of?
• Web Services
• Whole Web
• Semantic Web
• ??

Presentations: Candidate Solutions (1)

1:30-2:15pm

WS-Policy Presentation
BEA, IBM, Microsoft, SAP

2:15-3:00pm

RDF for Web Services Policy Assertions
Eric Prud'hommeaux, W3C

3:30-4:15pm

Declarative Policies
University of Maryland, Baltimore County

4:15-5:00pm

Position Paper
IBM

Presentations: Candidate Solutions (2)

8:45-9:45am

Comparing Features/Properties and WS-Policy
Sonic Software

9:45-10:30am

Position Paper
Oracle

11:00-11:45am

Position Paper
Sun Microsystems

11:45am-12:30pm

Position Paper
IONA Technologies

Discussion: Candidate Solutions

• Properties and Features Questions
• Semantic Web Questions
• WS-Policy Questions

Properties and Features

• How should work in this area relate to Properties and Features?
  • Build on top of them?
  • Separate from them?
  • Replacing them?

Semantic Web

• How should work in this area relate to the Semantic Web?
  • Based on RDF Syntax?
  • Based on RDF Model?
  • XML mapped to the RDF Model?
  • Based on Semantic Web Services?
  • Leverage RDF Schema? OWL? RuleML? Rei?
  • Should assertions be encouraged / required to be modeled in RDF?

WS-Policy

• Does WS-Policy meet your needs?
• Should the W3C wait for / solicit submission of WS-Policy? How Long?

Discussion: Deliverables

• How/when should the output be segmented? E.g.,
  • Model
  • Model extensions
  • Syntax
  • Syntax extensions
  • Attachment mechanisms
  • Assertion vocabularies
  • Delivery / Discovery

Discussion: Feedback to W3C

• Should the W3C pursue work in this area at all?
• When do you expect / need a solution?
• What dependencies upon this work exist?
• Is the problem well-defined enough to start a WG now? An IG?
• Would you send participants to a WG?