draft-lonnfors-simple-prescaps-ext-02

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draft-lonnfors-simple-prescaps-ext-02

• Mikko Lönnforsmikko.lonnfors_at_nokia.com
• IETF58

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Changes since -01 version

• Harmonization with draft-ietf-sip-callee-caps-01
• New XML schema
• Separate elements for all attributes
• Some editorial cleanup

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Open issue (ltcontact URIgt)

• What should be the contact URI if ltprescapsgt
  elements are present?
• In Indicating User Agent Capabilities in the
  Session Initiation Protocol (SIP) it is not
  recommended to assign feature sets into AoR
• In presence many services probably want to use
  AoR as contact URI
• Proposal not restrict SIP URIs that can be
  placed as contact URI

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Open issue (What capabilities)

• In Indicating User Agent Capabilities in the
  Session Initiation Protocol (SIP) it is
  recommended that UA should declare all features
  associated to particular Contact address
• In presence tuples can represent many things
  service, device, presentity.
• Also authorization policies may limit the
  information that is visible for watchers
• Proposal no need to express full feature sets
  but only those that are relevant for particular
  service/tuple

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Open issue (contacting particular UA)

• In the past there has been desire to enable
  routing based on ltprescapsgt elements
• Still, presence is more about user preferences
• Authorization policies may restrict watchers
  access to all ltprescapsgt elements
• Currently drafts says that building
  Accept-Contact based on ltprescapsgt elements can
  be done.
• Do we need something else?

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Open issue (syntax)

• List type of features (like methods)
• At a moment draft doesnt provide possibility
  for negations, separation between token/string
• Solution 1
• ltmethodsgtINVITE, !MESSAGE, OPTIONSlt/methodsgt
• Solution 2

• ltmethodsgt
• ltmethodgtINVITElt/methodgt
• ltmethod negated"true"gtMESSAGEgt
• lt/methodsgt

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Open issue (extension tags)

• At a moment only possibility to add new tags is
  to define new XML namespace. This is probably too
  heavy
• Proposal
• Define elements for different types of extension
  feature tags boolean, integer, string, token,
  range.
• ltstring name"new-string negatedtruegtFoobarlt/s
  tringgt
• lttoken name"new-token negatedfalsegtballlt/toke
  ngt

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Next Steps

• Adopt as WG item?