An Extensible Markup Language (XML) Configuration Access Protocol (XCAP) Diff Event Package
draft-ietf-sip-xcapevent-08

[Ballot comment]
I found the document to be difficult to read.

Some comments (some of which seem to be minor bugs in the document) are below:

4.4.  SUBSCRIBE Bodies

  The URI list is described by the XCAP resource list format [RFC4826],
  and is included as a body of the initial SUBSCRIBE request.  Only a
  simple subset of that format is required, a flat list of XCAP R-URIs.

The term R-URI is not used by RFC 4826.

  When subscribing to XCAP components, namespace prefixes of XCAP Node
  Selectors MUST be properly resolved to namespace URIs.  Section 6.4.
  of RFC 4825 [RFC4825] describes the conventions when using prefixes
  in XCAP Node Selectors.  If only XCAP Default Document Namespace is
  used, just like in the previous example ( element), the
  query component of the "uri" value is not required.

The previous example has no  element, as far as I can see.


4.7.  Notifier Generation of NOTIFY Requests

  While the "aggregate" mode uses bandwidth most efficiently, it
  introduces other challenges.  The initial synchronization might fail
  with rapidly changing resources, because the "aggregate" mode
  messages might not include the full version-history of a document and
  the base XCAP protocol does not support version-history retrievals of
  documents.  When new documents are created in subscribed collections
  and the notifier is aggregating patches, the same issue can occur.
  In a corner case, the notifier may not be able to provide patches
  with the XML-Patch-Ops [RFC5261] semantics.

What is the corner case?

  If, for example, the subscriber has selected too many elements to
  which to subscribe, such that the notification body would be
  impractically large (that is, an intermediate NOTIFY failure), the
  notifier MAY discard the  element content.  The existence of
  elements is then indicated with an empty  element, and the
  content is not shown for those resources.  In other words, the
    element does not not have a child element which would show

Double "not"

  the subscribed "full" element content.

[Ballot discuss]
In Section 5:

 
 

   

   

   
       
         
         
       
       
          presence
       
     

 


          Figure 2: An example initial XCAP Diff format document

  Note that the resource-list "index" document included only the new
  ETag value, as the document existed during the subscription time.  In
  the "pidf-manipulation" collection, there is only a single document
  for which the user has read privilege.  The  element exists

Did you mean  (no trailing "s") element?

  within the rls-services "index" document and its content is shown.
  Note also that the  element was located using the Default
  Document Namespace (no prefix in XCAP Node Selector value) although
  it has an "s" prefix in the source document.

[Ballot comment]
I found the document to be difficult to read.

Some comments (some of which seem to be minor bugs in the document) are below:

4.4.  SUBSCRIBE Bodies

  The URI list is described by the XCAP resource list format [RFC4826],
  and is included as a body of the initial SUBSCRIBE request.  Only a
  simple subset of that format is required, a flat list of XCAP R-URIs.

The term R-URI is not used by RFC 4826.

  When subscribing to XCAP components, namespace prefixes of XCAP Node
  Selectors MUST be properly resolved to namespace URIs.  Section 6.4.
  of RFC 4825 [RFC4825] describes the conventions when using prefixes
  in XCAP Node Selectors.  If only XCAP Default Document Namespace is
  used, just like in the previous example ( element), the
  query component of the "uri" value is not required.

The previous example has no  element, as far as I can see.


4.7.  Notifier Generation of NOTIFY Requests

  While the "aggregate" mode uses bandwidth most efficiently, it
  introduces other challenges.  The initial synchronization might fail
  with rapidly changing resources, because the "aggregate" mode
  messages might not include the full version-history of a document and
  the base XCAP protocol does not support version-history retrievals of
  documents.  When new documents are created in subscribed collections
  and the notifier is aggregating patches, the same issue can occur.
  In a corner case, the notifier may not be able to provide patches
  with the XML-Patch-Ops [RFC5261] semantics.

What is the corner case?

  If, for example, the subscriber has selected too many elements to
  which to subscribe, such that the notification body would be
  impractically large (that is, an intermediate NOTIFY failure), the
  notifier MAY discard the  element content.  The existence of
  elements is then indicated with an empty  element, and the
  content is not shown for those resources.  In other words, the
    element does not not have a child element which would show

Double "not"

  the subscribed "full" element content.



In Section 5:

 
 

   

   

   
       
         
         
       
       
          presence
       
     

 


          Figure 2: An example initial XCAP Diff format document

  Note that the resource-list "index" document included only the new
  ETag value, as the document existed during the subscription time.  In
  the "pidf-manipulation" collection, there is only a single document
  for which the user has read privilege.  The  element exists

Did you mean  (no trailing "s") element?

  within the rls-services "index" document and its content is shown.
  Note also that the  element was located using the Default
  Document Namespace (no prefix in XCAP Node Selector value) although
  it has an "s" prefix in the source document.

[Ballot discuss]
This is a DISCUSS DISCUSS. I intent to clear it once we have the discussion.

Should the new IANA registry be created for the following values:

        diff-processing = "diff-processing" EQUAL (
          "no-patching" /
          "xcap-patching" /
          "aggregate" /
          token )

?

[Ballot discuss]
It seems version -05 is a major rewrite of version -04. However,
I have only re-reviewed those parts where I had comments earlier.
Both comments seem to still apply:

The ABNF in Section 4.3 doesn't actually match what it's supposed to
match. Concatenation has higher precedence than alternatives, so it
needs parenthesis: currently it would match "diff-processing=no-patching"
or "xcap-patching", but not "diff-processing=xcap-patching".

The examples in Appendix A contain some invalid XML -- I didn't
actually run a validator, but some of it isn't even well-formed
(such as "").

[Ballot discuss]
The more I dig into this document, the more I worry about the changes required to make it unambiguous.  This may need to go back to the WG.

[Ballot comment]
In addition to the ABNF problem Pasi noticed, the ABNF in this document
depends on ABNF in RFC 3261, but that's not mentioned.  One way to fix
this is to add "import rules" like:

  EQUALS =
  token  =

Alternatively, just say you're importing some rules from RFC 3261.

[Ballot discuss]
I have reviewed draft-ietf-sip-xcapevent-04. Overall, the document
looks good, but I have couple of nits about the formal languages used
in the document:

It seems the ABNF in Section 4.3 doesn't actually match what it's
supposed to match (concatenation has higher precedence than
alternatives, so it needs parenthesis?).

The examples in Appendix A contain some invalid XML -- I didn't
actually run a validator, but e.g. "" is clearly
wrong, and in some cases (e.g. last example in A.4), handling of
namespaces doesn't look OK.

[Ballot comment]
I have a bunch of editorial concerns with this document: requirements sentences with vague antecedents and other language issues that may even affect implementations and interoperability.  What I can do if the authors are willing is sit down and find out what the intent was, and help fix those sentences.

IANA Last Call comments:

Upon approval of this document, the IANA will make the following
assignmentin the "Session Initiation Protocol (SIP) Event Types
Namespace - per [RFC3427]" registry at
http://www.iana.org/assignments/sip-events

Package Name Type Contact Reference
------------- -------- ------- ---------
xcap-diff package IETF SIP Working Group [RFC-sip-xcapevent-03]


We understand the above to be the only IANA Action for this
document.

The SIP WG wishes to request publication of the standards-track 
document draft-ietf-sip-xcapevent. This is a product of the SIP 
working group, and a protocol shepherd writeup follows.

1.a)  Who is the Document Shepherd for this document?  Has the
          Document Shepherd personally reviewed this version of the
          document and, in particular, does he or she believe this
          version is ready for forwarding to the IESG for publication?

The Document Shepherd is SIP working group chair Dean Willis. He has
personally reviewed this version of the document and believes it is
ready for forwrding to the IESG for publication.


  (1.b)  Has the document had adequate review both from key WG members
          and from key non-WG members?  Does the Document Shepherd have
          any concerns about the depth or breadth of the reviews that
          have been performed?

The document has been thoroughly reviewed in the working
group. Further review was requested and received from the Open Mobile
Alliance's Presence and Availability working group, which is expected
to be a major user of the specification. Specialized event-package
review was provided by Adam Roach, author of the SIP Events
specification RFC 3325.


  (1.c)  Does the Document Shepherd have concerns that the document
          needs more review from a particular or broader perspective,
          e.g., security, operational complexity, someone familiar with
          AAA, internationalization or XML?

The shepherd has no concerns that the document requires additional or
broader review.


  (1.d)  Does the Document Shepherd have any specific concerns or
          issues with this document that the Responsible Area Director
          and/or the IESG should be aware of?  For example, perhaps he
          or she is uncomfortable with certain parts of the document, or
          has concerns whether there really is a need for it.  In any
          event, if the WG has discussed those issues and has indicated
          that it still wishes to advance the document, detail those
          concerns here.  Has an IPR disclosure related to this document
          been filed?  If so, please include a reference to the
          disclosure and summarize the WG discussion and conclusion on
          this issue.

The shepherd has no specific concerns with this document, and is
unaware of any IPR disclosure related to this document.


  (1.e)  How solid is the WG consensus behind this document?  Does it
          represent the strong concurrence of a few individuals, with
          others being silent, or does the WG as a whole understand and
          agree with it?

There is strong working group consensus behind this document. It is
the evolution of several years work related to use of XCAP for
configuration delivery and for managing subscriber and buddy lists.


  (1.f)  Has anyone threatened an appeal or otherwise indicated extreme
          discontent?  If so, please summarise the areas of conflict in
          separate email messages to the Responsible Area Director.  (It
          should be in a separate email because this questionnaire is
          entered into the ID Tracker.)

The shepherd is not aware of any significant discontent related to
this draft.


  (1.g)  Has the Document Shepherd personally verified that the
          document satisfies all ID nits?  (See
          http://www.ietf.org/ID-Checklist.html and
          http://tools.ietf.org/tools/idnits/).  Boilerplate checks are
          not enough; this check needs to be thorough.  Has the document
          met all formal review criteria it needs to, such as the MIB
          Doctor, media type and URI type reviews?

The shepherd verified that the draft satisfies all ID nits to the best
of his ability. It does have one slightly stale reference to
draft-ietf-simple-xcap-diff-08 which is now in -09, but this does not
impact the draft.


  (1.h)  Has the document split its references into normative and
          informative?  Are there normative references to documents that
          are not ready for advancement or are otherwise in an unclear
          state?  If such normative references exist, what is the
          strategy for their completion?  Are there normative references
          that are downward references, as described in [RFC3967]?  If
          so, list these downward references to support the Area
          Director in the Last Call procedure for them [RFC3967].

References are appropriately split. The draft does depend on
draft-ietf-simple-xcap-diff and on draft-ietf-sip-subnot-etags, both
of which should be ready for review in approximately the same time
frame. There are no known downrefs.


  (1.i)  Has the Document Shepherd verified that the document IANA
          consideration section exists and is consistent with the body
          of the document?  If the document specifies protocol
          extensions, are reservations requested in appropriate IANA
          registries?  Are the IANA registries clearly identified?  If
          the document creates a new registry, does it define the
          proposed initial contents of the registry and an allocation
          procedure for future registrations?  Does it suggest a
          reasonable name for the new registry?  See [RFC2434].  If the
          document describes an Expert Review process has Shepherd
          conferred with the Responsible Area Director so that the IESG
          can appoint the needed Expert during the IESG Evaluation?

The IANA considerations appear to be correct.


  (1.j)  Has the Document Shepherd verified that sections of the
          document that are written in a formal language, such as XML
          code, BNF rules, MIB definitions, etc., validate correctly in
          an automated checker?

The shepherd verified the BNF and XML. Since the XML was verified with
the author's own popular XML verifier, no errors were really expected.


  (1.k)  The IESG approval announcement includes a Document
          Announcement Write-Up.  Please provide such a Document
          Announcement Write-Up?  Recent examples can be found in the
          "Action" announcements for approved documents.  The approval
          announcement contains the following sections:

Technical Summary

The XCAP (XML Confgiration Access Protocol, RFC 4825) protocol
provides for change control on structured data. This specification
provides a SIP Event Paackage (RFC 3325) that can be used to monitor
changes to an XCAP document. Change notifications may include
differential changes expressed using the XCAP-Diff format described in
draft-ietf-simple-xcap-diff. This specification also provides for
initial synchronization between a stored version of an XCAP document
and a remote copy being monitored using the protocol of thsi 
specification.


Working Group Summary

This specification developed out of the larger body of configuration
management work related to SIP (RFC 3261). In particular, it relates
to XCAP (RFC 4825) and the SIP Configuration Framework
(draft-ietf-sipping-config-framework). The content of this
specification was split off from the configuration framework document
about two years ago, and has progressed indepdently.


          Document Quality
            Are there existing implementations of the protocol?  Have a
            significant number of vendors indicated their plan to
            implement the specification?  Are there any reviewers that
            merit special mention as having done a thorough review,
            e.g., one that resulted in important changes or a
            conclusion that the document had no substantive issues?  If
            there was a MIB Doctor, Media Type or other expert review,
            what was its course (briefly)?  In the case of a Media Type
            review, on what date was the request posted?

Document Quality

There are existing implementations of earlier versions of the
protocol, and a significant number of vendors have committed to
implementation of the specification in the context of the Open Mobile
Alliances's Push-to-Talk Over Cellularspecification. Adam Roach
provided specific guidance and review on the SIP Event Package aspects
of this specification.