1. Slide #1 Nov 6 – 11, 2005XCON WG IETF54 Conference Package Extensions draft-levin-xcon-conference-package-ext-00 by Orit Levin The Discussion Starter

2. Slide #2 Nov 6 – 11, 2005XCON WG IETF54 The Objectives How? - Define extensibility guidelines What info? - Define additional conferencing data Expose the main objects to external schemas

3. Slide #3 Nov 6 – 11, 2005XCON WG IETF54 How the Conference Package can be extended The XML-related issues…

4. Slide #4 Nov 6 – 11, 2005XCON WG IETF54 The Basic Package Extensibility ………………………………………………………………….

5. Slide #5 Nov 6 – 11, 2005XCON WG IETF54 The Conference Package Extensibility Requirements IETF MUST be capable to extend any schema construct with additional elements A vendor MUST be capable to extend any schema construct with additional elements It MUST be possible to have extensions from different namespaces in a single XML document The resultant document MUST adhere to a valid schema The standard extended documents MUST be backwards compatible

6. Slide #6 Nov 6 – 11, 2005XCON WG IETF54 The Naïve Approach Results in Invalid XML ………………………………………………………………….

7. Slide #7 Nov 6 – 11, 2005XCON WG IETF54 The XML Extensibility Issue According to the XML standard, a parser recognizing document element contents MUST be able to decide, without look ahead, which content model token to match with the current input token, while processing the document from left to right This requirement creates the known “ambiguous content” problem, which makes the XML extensibility difficult Different applications use different approaches, but no “ultimate” solution exists Some implementations just don’t schematize the extensions as an integral part of the.xsd, instead they process the extension section “manually”, i.e. outside of the XML automatic one step parsing

8. Slide #8 Nov 6 – 11, 2005XCON WG IETF54 Extensibility: The Proposed Solution ………………………………………………………………….

9. Slide #9 Nov 6 – 11, 2005XCON WG IETF54 What It Gives Us For the entity receiving the document –This is a valid schema, and therefore can be parsed by an XML compliant compiler For the entity generating the document –If no extensions are included in the document, the “separator” doesn’t have to be included either Extensions can be introduced in steps (e.g. versions) as long as the order is known Extensions can belong to different namespaces

10. Slide #10 Nov 6 – 11, 2005XCON WG IETF54 Example1: A Single Step Standard or Vendor Extensions ………………………………………………………………….

11. Slide #11 Nov 6 – 11, 2005XCON WG IETF54 Example2: Standard and Vendor Extensions ………………………………………………………………….

12. Slide #12 Nov 6 – 11, 2005XCON WG IETF54 The Proposed Solution Properties Summary Pros: –Backwards compatible with the basic conference package –Automatic parsing by a standard XML compiler The limitation – the extensions order must be known and predefined in the.xsd –Every time a standard extension is defined its order MUST be defined relatively to already defined standard extensions –In order to support a new standard extension, the.xsd needs to be rearranged such that all proprietary extensions appear after the latest standard extension –If extensions from different vendors need to be supported by a certain product, the order of these extensions needs to be agreed upon

13. Slide #13 Nov 6 – 11, 2005XCON WG IETF54 What information needs to be added to the basic package and why …

14. Slide #14 Nov 6 – 11, 2005XCON WG IETF54 The Actual Extensions Conference state that needs to be distributed to subscribers Candidates for extensions: –Floor Control identifiers and state –Authorization information –Etc.

15. Slide #15 Nov 6 – 11, 2005XCON WG IETF54 Using the Conference Package XML definitions for more than events only For Conference Control Protocols…

16. Slide #16 Nov 6 – 11, 2005XCON WG IETF54 Exposing the Main Objects Reason: reusing parts of the schema without prefixing each internal element The root “conference” object exists already: <xs:element name="conference-info" type="conference- type" The suggested schema additions:

17. Slide #17 Nov 6 – 11, 2005XCON WG IETF54 Example: addConference() CCCP Primitive Definition xmlns:ci="urn:ietf:params:xml:ns:conference-info"

18. Slide #18 Nov 6 – 11, 2005XCON WG IETF54 The Corresponding XML Document Phone conference to discuss our design tel:+1-8666119036 pstn bridge

19. Slide #19 Nov 6 – 11, 2005XCON WG IETF54 Example: addUser() CCCP Primitive Definition xmlns:ci="urn:ietf:params:xml:ns:conference-info"

20. Slide #20 Nov 6 – 11, 2005XCON WG IETF54 The Corresponding XML Document <user entity="sip:bob@example.com“ xmlns="urn:ietf:params:xml:ns:conference-info"> Bob Hoskins presenter

21. Slide #21 Nov 6 – 11, 2005XCON WG IETF54 Thank you! The Conference Control Protocol discussion will be continued tomorrow…