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Conference Package Extensions draft-levin-xcon-conference-package-ext-00 by Orit Levin

Conference Package Extensions draft-levin-xcon-conference-package-ext-00 by Orit Levin. The Discussion Starter. The Objectives. How? - Define extensibility guidelines What info? - Define additional conferencing data Expose the main objects to external schemas.

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Conference Package Extensions draft-levin-xcon-conference-package-ext-00 by Orit Levin

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  1. Conference Package Extensionsdraft-levin-xcon-conference-package-ext-00by Orit Levin The Discussion Starter XCON WG IETF54

  2. The Objectives • How? - Define extensibility guidelines • What info? - Define additional conferencing data • Expose the main objects to external schemas XCON WG IETF54

  3. How the Conference Package can be extended The XML-related issues… XCON WG IETF54

  4. The Basic Package Extensibility <xs:complexType name="conference-description-type"> <xs:sequence> <xs:element name="display-text" type="xs:string" minOccurs="0"/> …………………………………………………………………. <xs:element name="available-media" type="conference-media-type" minOccurs="0"/> <xs:any namespace="##other" processContents="lax“ maxOccurs="unbounded"/> </xs:sequence> </xs:sequence> <xs:anyAttribute namespace="##other" processContents="lax"/> </xs:complexType> XCON WG IETF54

  5. 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 XCON WG IETF54

  6. The Naïve ApproachResults in Invalid XML <xs:complexType name="conference-description-type"> <xs:sequence> <xs:element name="display-text" type="xs:string" minOccurs="0"/> …………………………………………………………………. <xs:element name="available-media" type="conference-media-type" minOccurs="0"/> <xs:element ref="cix:disclaimer" minOccurs="0"/> <xs:any namespace="##other" processContents="lax" maxOccurs="unbounded"/> </xs:sequence> <xs:anyAttribute namespace="##other" processContents="lax"/> </xs:complexType> XCON WG IETF54

  7. 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 XCON WG IETF54

  8. Extensibility:The Proposed Solution <xs:complexType name="conference-description-type"> <xs:sequence> <xs:element name="display-text" type="xs:string" minOccurs="0"/> …………………………………………………………………. <xs:element name="available-media" type="conference-media-type" minOccurs="0"/> <xs:element ref="cix:disclaimer" minOccurs="0"/> <xs:sequence minOccurs="0"> <xs:element ref="cis:separator"/> <xs:any namespace="##other" processContents="lax" maxOccurs="unbounded"/> </xs:sequence> </xs:sequence> <xs:anyAttribute namespace="##other" processContents="lax"/> </xs:complexType> XCON WG IETF54

  9. 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 XCON WG IETF54

  10. Example1: A Single StepStandard or Vendor Extensions <xs:complexType name="conference-description-type"> <xs:sequence> <xs:element name="display-text" type="xs:string" minOccurs="0"/> …………………………………………………………………. <xs:element name="available-media" type="conference-media-type" minOccurs="0"/> <xs:element ref=“cix:disclaimer" minOccurs="0"/> <xs:sequence minOccurs="0"> <xs:element ref="cis:separator"/> <xs:any namespace="##other" processContents="lax" maxOccurs="unbounded"/> </xs:sequence> </xs:sequence> <xs:anyAttribute namespace="##other" processContents="lax"/> </xs:complexType> XCON WG IETF54

  11. Example2:Standard and Vendor Extensions <xs:complexType name="conference-description-type"> <xs:sequence> <xs:element name="display-text" type="xs:string" minOccurs="0"/> …………………………………………………………………. <xs:element name="available-media" type="conference-media-type" minOccurs="0"/> <xs:element ref="cix:disclaimer" minOccurs="0"/> <xs:element ref=“ms:disclaimer" minOccurs="0"/> <xs:sequence minOccurs="0"> <xs:element ref="cis:separator"/> <xs:any namespace="##other" processContents="lax" maxOccurs="unbounded"/> </xs:sequence> </xs:sequence> <xs:anyAttribute namespace="##other" processContents="lax"/> </xs:complexType> XCON WG IETF54

  12. The Proposed Solution PropertiesSummary • 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 XCON WG IETF54

  13. What information needs to be added to the basic package and why … XCON WG IETF54

  14. The Actual Extensions • Conference state that needs to be distributed to subscribers • Candidates for extensions: • Floor Control identifiers and state • Authorization information • Etc. XCON WG IETF54

  15. Using the Conference Package XML definitions for more than events only For Conference Control Protocols… XCON WG IETF54

  16. 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: <xs:attribute name="state" type="state-type"/> <xs:element name="media" type="media-type"/> <xs:element name="endpoint" type="endpoint-type"/> <xs:element name="user-roles" type="user-roles-type"/> <xs:element name="user" type="user-type"/> XCON WG IETF54

  17. Example: addConference()CCCP Primitive Definition xmlns:ci="urn:ietf:params:xml:ns:conference-info" <xs:complexType name="add-conference-type"> <xs:sequence> <xs:element ref="ci:conference-info"/> <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> <xs:anyAttribute namespace="##other“ processContents="lax"/> </xs:complexType> XCON WG IETF54

  18. The Corresponding XML Document <addConference> <conference-info entity="sip:Conf1@example.com" xmlns="urn:ietf:params:xml:ns:conference-info"> <conference-description> <subject>Phone conference to discuss our design</subject> <conf-uris> <entry> <uri>tel:+1-8666119036</uri> <display-text>pstn bridge</display-text> </entry> </conf-uris> </conference-description> </conference-info> </addConference> XCON WG IETF54

  19. Example: addUser()CCCP Primitive Definition xmlns:ci="urn:ietf:params:xml:ns:conference-info" <xs:complexType name="add-user-type"> <xs:sequence> <xs:element name="conferenceKeys" type="tns:conference-keys-type"/> <xs:element ref="ci:user"/> <xs:any namespace="##other" processContents="lax" minOccurs="0“ maxOccurs="unbounded"/> </xs:sequence> <xs:anyAttribute namespace="##other" processContents="lax"/> </xs:complexType> XCON WG IETF54

  20. The Corresponding XML Document <addUser> <conferenceKeys confEntity="sip:conf233@example.com"/> <user entity="sip:bob@example.com“ xmlns="urn:ietf:params:xml:ns:conference-info"> <display-text>Bob Hoskins</display-text> <roles> <entry>presenter</entry> </roles> </user> </addUser> XCON WG IETF54

  21. Thank you! The Conference Control Protocol discussion will be continued tomorrow… XCON WG IETF54

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