Patrick,

Thank you for your review and feedback.  I provide answers to your feedback 
below.

-- 
 
JG



James Gould
Fellow Engineer
jgo...@verisign.com 
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On 4/27/20, 1:08 AM, "regext on behalf of Patrick Mevzek" 
<regext-boun...@ietf.org on behalf of p...@dotandco.com> wrote:

    On Mon, Mar 16, 2020, at 09:28, Gould, James wrote:
    >  
    > One question that was raised by Patrick Mevzek on the mailing list was 
    > associated with signaling the implementation of a BCP by the server 
    > that I believe would also apply to the client. This question applies to 
    > the two REGEXT BCP drafts draft-ietf-regext-secure-authinfo-transfer 
    > and draft-ietf-regext-unhandled-namespaces.
    
    Aside, for this last one that is using extValue I think the extValue should
    be more properly categorized to be related to this extension.
    
    Rationale:
    1) even if you put a message in <reason>, this part is clearly for humans,
    so no software should have to rely on this content
    2) extValue can be used for many things. In fact the way the draft is using 
it
    is kind of violating what RFC 5730 says about it:
    "A <value> element that identifies a client-provided element
                (including XML tag and value) that caused a server error
                condition."
    
    What will now be put there is NOT client-provided but server-provided.
    Which is also one of the reason why I have mixed feelings to handle
    unhandled namespaces that way even if there are no other proposals.
    
    So at least maybe something like:
    <extValue>
    <value xmlns:unhandled="....">
    <unhandled:content>
    
    (here would appear the XML part that the server wants to give but can't 
    because the associated namespace was not selected by client at login)
    
    </unhandled:content>
    </value>
    </extValue>
    
    
    Introducing new content can break existing client without proper signalling.
    You might say that if clients have to be updated to do that, they might as 
well
    be updated to correctly handle the unhandled namespace part, but as 
discussed
    previously already, things are not so simple in real life.

JG - Providing an explicit reason as defined in the draft will enable the 
client to monitor for an unhandled namespace.  In the Verisign EPP SDK, I was 
able to leverage the preformatted reason to easily pull out the namespaces that 
are unhandled in a utility method.  I realize that the reason is meant to be 
human readable, but in this case it helps the client software to monitor for 
unhandled namespaces.  By including the XML of the unhandled namespace in the 
<value> element, it provides the option for the client to record the unhandled 
information for later processing.  Including additional XML around the 
unhandled XML doesn't really help the client.  I found it extremely straight 
forward to filter the unhandled namespace XML for poll messages and for regular 
responses, and identifying the processing the unhandled namespaces in the 
client.  I recommend that you try creating a client utility method for 
unhandled namespaces in your Perl EPP SDK to see how straight forward it is.  
Hopefully we can discuss your proposal at the WG meeting today.  
    
    > The only existing signaling 
    > mechanism in EPP is the use of the greeting and login services. A 
    > namespace URI could be assigned for each BCP draft that is included as 
    > an <objURI> or an <extURI> in the greeting to inform the client of the 
    > support of the BCP by the server, and in the login command to inform 
    > the server of the support of the BCP by the client. Between the two 
    > options, I prefer the use of the <extURI>. The questions for the 
    > working group include:
    > 
    > 
    >  1. Is signaling needed in EPP for the implementation of BCPs?
    
    I think so.

JG - Agreed
    
    >  2. If signaling is needed:    1. Will the existing signaling mechanism 
    > in EPP with the greeting and login services meet the purpose?
    
    There is currently no other option.
    Contrary to TLS handshake for example where each part is able to offer
    details on its capabilities before deciding to pursue the exchange or not,
    in EPP the client has to accept what the server says, or do nothing.
    
JG - The only other option is to create an extension to serve the purpose of 
BCP signaling, but I believe the use of the login and greeting services meets 
the need.

    >    2. Of the two service URIs <objURI> and <extURI>, which is the 
    > preferred URI to use?
    
    extURI is the only one matching semantically.
    RFC 5730 says:
    " One or more <objURI> elements that contain namespace URIs
             representing the objects that the server is capable of
             managing. "
    
    
    If the namespace URI is not about an object, then it shouldn't be
    an objURI.

JG - Agreed
    
    >    3. What URI scheme should be used? 
    > i. One proposal is to include bcp in the namespace, such as 
    > “urn:ietf:params:xml:ns:epp:bcp:secure-authinfo-transfer-<version>” and 
    > “urn:ietf:params:xml:ns:epp:bcp:unhandled-namespaces-<version>”. The 
    > <version> would be updated based on material updates to the BCP draft 
    > and bumped to 1.0 after WGLC. 
    
    I am not sure of what I think, but I am not immediately a huge fan of 
    putting bcp in the namespace. I do not know if there are other examples
    in other working group/the IETF, but the main problem I see is that
    BCPs can change during time, and you won't be able to change the namespace
    once it has this in its name.

JG - The bcp namespace in the URI is used to put the namespace URI in an 
appropriate category, which in this case is for EPP BCPs.  If and when the BCP 
changes materially, the <version> will change in the URI.  I updated the drafts 
with the following IANA URI registrations:

urn:ietf:params:xml:ns:epp:bcp:unhandled-namespaces-0.1
urn:ietf:params:xml:ns:epp:bcp:secure-authinfo-transfer-0.1

If there is a material change to the drafts, the version will be bumped up to 
0.2, and so forth.  Once the drafts make it past WGLC, the version will be 
bumped up to 1.0.  The scheme to use will be discussed during the WG meeting.   
    
    -- 
      Patrick Mevzek
      p...@dotandco.com
    
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