Re: [MMUSIC] Starting shepherd's review of draft-ietf-mmusic-t140-usage-data-channel-07 - Bo's technical comments

[Gunnar Hellström <[e-mail]>]

Hi,

I am sorry, I have not yet found a reference for the common look of 
messages with a leading source label that I called "IRC style".

Anyone knows?

Regards

Gunnar

Den 2019-11-07 kl. 16:01, skrev Christer Holmberg:
> Hi,
>
> I have updated the pull request based on Bo's technical comments. Please take a look.
>
> https://github.com/cdh4u/draft-datachannel-t140/pull/52
>
> Gunnar, which RFC should I add as reference for the IRC labels?
>
> Regards,
>
> Christer
>
>
>
> On 07/11/2019, 15.34, "Bo Burman" <[e-mail]> wrote:
>
>      Yes, I agree that should resolve the  issue I had with the text.
>      Thanks,
>      /Bo
>      
>      > -----Original Message-----
>      > From: Gunnar Hellström <[e-mail]>
>      > Sent: den 7 november 2019 14:13
>      > To: Christer Holmberg <[e-mail]>; Bo Burman
>      > <[e-mail]>; mmusic ([e-mail])
>      > <[e-mail]>
>      > Subject: Re: [MMUSIC] Starting shepherd's review of draft-ietf-mmusic-t140-
>      > usage-data-channel-07 - Bo's technical comments
>      >
>      > Hi,
>      >
>      > Christer, I accept your proposal below. With the remaining text it should be
>      > apparent for all that the solution has limitations.
>      >
>      > I hope also Bo thinks that the issues are solved now.
>      >
>      > Regards
>      >
>      > Gunnar
>      >
>      >
>      > Den 2019-11-07 kl. 14:06, skrev Christer Holmberg:
>      > > Hi,
>      > >
>      > >>> In the first paragraph we say that one needs to use separate data
>      > >>> channels, so it sounds strange to then have a note saying that is not true.
>      > Also, the way you suggest the text makes it look like you are defining a
>      > mechanism for using a single channel.
>      > >> Yes, I realized the conflict and tried to avoid it by the words
>      > >> "limited functionality multi-party RTT presentation in one display area",
>      > and "This presentation style does not meet all RTT requirements".
>      > >>
>      > >> But maybe that was not obvious. So, I accept your proposal below with
>      > >> some modifications
>      > >>
>      > >>> Maybe something like this:
>      > >>>
>      > >>> "The usage of a single T.140 data channel, without any protocol
>      > extensions, would require the conference server to only forward
>      > >>>   real-time text from one source at any given time, and e.g., include IRC
>      > style text labels in the real-time text in order for the receiver
>      > >>>   to separate real-time text from different sources. The procedures of
>      > such mechanism is outside the scope of this document."
>      > >> Yes, quite good, I suggest a few modifications to:
>      > >>
>      > >> "The usage of a single T.140 data channel, without any protocol
>      > >> extensions, would require the conference server to only forward
>      > >> real-time text from one source at any given time, and e.g., include
>      > >> IRC style text labels in the real-time text in order for the receiver to
>      > present real-time text from different sources separated. The procedures of
>      > such mechanisms cause functional limitations and are outside the scope of
>      > this document."
>      > > I am ok to replace 'separate' with 'present', but with the modification to the
>      > last sentence you would still have the question what those 'functional
>      > limitations' are,  and we would need to include additional text...
>      > >
>      > > So, I suggest that we remove the text about functional limitations.
>      > >
>      > > Regards,
>      > >
>      > > Christer
>      > >
>      > >
>      > >
>      > >
>      > >
>      > > From: Gunnar Hellström mailto:[e-mail]
>      > > Sent: Wednesday, November 6, 2019 9:44 PM
>      > > To: Christer Holmberg mailto:[e-mail]; Bo Burman
>      > > mailto:bo.burman=[e-mail]; mmusic
>      > > (mailto:[e-mail]) mailto:[e-mail]
>      > > Subject: Re: [MMUSIC] Starting shepherd's review of
>      > > draft-ietf-mmusic-t140-usage-data-channel-07 - Bo's technical comments
>      > >
>      > > Hi,
>      > > Even if I accepted to delete the last sentence in section 5 on multi-party, I
>      > want to propose a solution that might better address the original issue 5.
>      > >
>      > > So, this is a proposal for new wording of the last sentence in 5, as a solution
>      > on issue 5:
>      > > "Conference mixers that use a single T.140 data channel
>      > >     to transmit real-time text towards clients might however without any
>      > protocol extensions produce a limited functionality multi-party RTT
>      > presentation in one display area. Only one source at a time can be presented
>      > in real-time, but switch of source of text to display in real-time can be made
>      > automatically by the mixer and at suitable points in the text streams. Sources
>      > could be identified by inline text labels in IRC style. This presentation style
>      > does not meet all RTT requirements and if used, should be a temporary
>      > fallback method for conference-unaware clients."
>      > >
>      > > This wording is a self sustained description on what is possible and would
>      > also match better the recently revived work on multi-party rtt.
>      > >
>      > > Regards
>      > >
>      > > Gunnar
>      > >
>      > >
>      > >
>      > > Den 2019-11-06 kl. 17:29, skrev Christer Holmberg:
>      > > Bo, are you ok with the proposals?
>      > >
>      > > Regards,
>      > >
>      > > Christer
>      > >
>      > >
>      > > From: Gunnar Hellström mailto:[e-mail]
>      > > Sent: Wednesday, November 6, 2019 5:16 PM
>      > > To: Christer Holmberg mailto:[e-mail]; Bo Burman
>      > > mailto:bo.burman=[e-mail]; mmusic
>      > > (mailto:[e-mail]) mailto:[e-mail]
>      > > Cc: 'mailto:[e-mail]'
>      > > mailto:[e-mail]
>      > > Subject: SV: [MMUSIC] Starting shepherd's review of
>      > > draft-ietf-mmusic-t140-usage-data-channel-07 - Bo's technical comments
>      > >
>      > > Christer,
>      > > I agree with your proposals.
>      > >
>      > > Regards
>      > > Gunnar
>      > >
>      > > ----------------------------------------------------------------------
>      > > Gunnar Hellström
>      > > Omnitor
>      > > mailto:[e-mail]
>      > > [phone]
>      > >
>      > > Från: Christer Holmberg mailto:[e-mail]
>      > > Skickat: den 6 november 2019 09:58:30
>      > > Till: Gunnar Hellström mailto:[e-mail]; Bo Burman
>      > > mailto:bo.burman=[e-mail]; mmusic
>      > > (mailto:[e-mail]) mailto:[e-mail]
>      > > Kopia: 'mailto:[e-mail]'
>      > > mailto:[e-mail]
>      > > Ämne: Re: [MMUSIC] Starting shepherd's review of
>      > > draft-ietf-mmusic-t140-usage-data-channel-07 - Bo's technical comments
>      > >
>      > > Hi,
>      > >
>      > > ---
>      > > 3) In section 4.2.1, it says that “If the 'fmtp' attribute is not included, it
>      > indicates that no maximum character transmission rate is indicated.  It does
>      > not mean that the default value of 30 applies”; >why is this deviation from
>      > RFC 4103 chosen? Does it introduce a risk for interoperability problems with
>      > systems that also doesn’t use fmtp but interprets it as maximum 30 cps?
>      > > Gunnar?
>      > > [GH] I don't know why this deviation was chosen. But I have not
>      > commented it. You are right that it may introduce an increased risk for
>      > interoperability problems. But RFC 4103 has a precaution. In chapter 6, where
>      > the cps is introduced, it is said:
>      > > "
>      > >     receivers of text/t140 MUST be designed so they can handle temporary
>      > >     reception of characters at a higher rate than this parameter
>      > >     specifies.  As a result malfunction due to buffer overflow is avoided
>      > >     for text conversation with human input."
>      > >
>      > > (the reason for this note is for backward compatibility with RFC 2793,
>      > > the obsoleted predecessor of RFC 4103, so it is not exactly our case, but still
>      > valid.) We have discussed the risk that implementations may not implement
>      > setting or reading the dcsa attributes because of the complexity to do so
>      > alongside with the WebRTC API. That situation may cause a situation where a
>      > sent cps parameter is not obeyed. So the case is quite similar to the case in
>      > RFC 4103, and applications would be required to prepare for handling
>      > temporary reception at high rates.
>      > > The intention of T.140 is to handle real-time text conversation between
>      > humans. Huge cut and paste chunks of text cannot be required to be
>      > handled rapidly. The highest speed human interaction would be with speech-
>      > to-text applications. A very rapid speaker may produce 200 words per
>      > minute. That is 17 characters per second. The speech-to-text applications
>      > often makes corrections by long backspaces and resendings. That may add 10
>      > characters per second in the total. That results in a practical need of up to 27
>      > characters per second for one stream.
>      > > This calculation shows that for two-party calls, it would not hurt to use the
>      > same convention regarding cps default as RFC 4103 (30).
>      > > For centralized conference solutions with just one data channel from the
>      > conference server discussed in section 5.5, the need would be a multiple of
>      > that rate (27) corresponding to the number of simultaneous text senders. In
>      > well managed conferences this multiple is very close to one.
>      > > The figures above are extremes. Currently most use of RTT is typing at
>      > maximum speeds of about 7 characters per second.
>      > > Leaving the default to unrestricted might attract some misuse by
>      > implementations or users trying to use the T.140 data channel for data
>      > transmission of data totally different from the intended real-time text.
>      > > Conclusion after all this discussion:
>      > > Neither leaving the default to unlimited, nor changing to a default of 30 cps
>      > as in RFC 4103 seems very critical. Any solution will do.
>      > >
>      > > [Christer] I am pretty sure IESG would ask about this too, I suggest that we
>      > change the default to 30 cps.
>      > >
>      > > ---
>      > > ​5) In section 5.5, in the note, it says ‘…with limitations in real-time
>      > performance and presentation style’; I think it would be helpful to briefly
>      > elaborate on what type of limitations would be >expected and why.
>      > > I think it is explained in the other text of the section. For example, using a
>      > single data channel without any protocol extensions would not allow to
>      > separate the sources etc.
>      > > [GH] I think we can offer a bit more text at the end of the note to clarify.
>      > How about this:
>      > > "T.140 shows two examples of presentation layout for real-time text, one
>      > being column oriented, with one column per participant, another being
>      > arranged in one column with labels identifying the beginning of text from
>      > each participant and text from a number of participants received and placed
>      > in places corresponding to these different participants. With a conference
>      > mixer using one text stream and not applying any presentation protocol
>      > extension would only be able to produce a string for presentation in one
>      > column, including a source label in the beginning of text from one participant
>      > and only show text in real time from one participant at a time, shifting real-
>      > time presented participant at suitable points in the text stream. (end of
>      > phrase, end of sentence, line separator, long delay etc.). This presentation
>      > style may not be preferred by the user and it may cause delay before
>      > presentation of text from other than the currently presenting participant."
>      > > Pew, maybe too long and detailed....
>      > >
>      > > [Christer] Or, could we simply remove the last sentence ("Conference
>      > mixers that...")? The 1st paragraph already says why separate channels are
>      > needed, and the note says that future extensions may allow usage of a single
>      > channel, so I think it is pretty clear that using a single channel without any
>      > such extensions would come with limitations.
>      > >
>      > > ---
>      > >
>      > > 6) In section 6, bullet “If the gateway detects or suspects loss of data on the
>      > RTP stream…”; shouldn’t it await possible redundancy first and missing text
>      > marker is inserted only when the used >redundancy is not capable to repair
>      > the loss?
>      > > Gunnar?
>      > > [GH]The intention was that it would mean "after using possibly received
>      > redundant data".   You could interpret "loss of data" to mean that (instead of
>      > "loss of packets"), but let me try an improvement: "If the gateway detects or
>      > suspects loss of data on the RTP stream, after use of possibly received
>      > redundant data, …"
>      > >
>      > > [Christer] What about?
>      > >
>      > >
>      > > "If the gateway detects or suspects loss of data on the RTP stream, and the
>      > lost data has not been retrieved using a redundancy mechanism, the
>      > gateway SHOULD insert the T.140 missing text marker [T140ad1] in the data
>      > sent on the outgoing T.140 data channel."
>      > > ---
>      > >
>      > > 12) In section 11.1, in the [T140ad1] reference, is “aEUR” really part of the
>      > name? The name I find listed on the ITU-T web is “ITU-T T.140 (1998) Add. 1
>      > (02/2000)”, and the title in the document >itself seems to be “Protocol for
>      > multimedia application text conversation; Addendum 1”.
>      > > Interesting. There is no "aEUR" in the XML file, so this seems to be
>      > something created by XML2RFC.
>      > >
>      > > The intended title is:
>      > >
>      > >     Recommendation ITU-T.140 – Addendum 1  (02/2000), "Protocol for
>      > multimedia application text conversation"
>      > >
>      > > I will fix it.
>      > > [GH] I chased a number of such occurrences earlier. I think it was because
>      > your editor inserted an unusual slanting quotation mark. Note that there is
>      > also a double quotation mark on the third line of the same reference.
>      > >
>      > > [Christer] I will double check.
>      > >
>      > > ---
>      > >
>      > > Regards,
>      > >
>      > > Christer
>      > >
>      > >
>      > --
>      >
>      > + + + + + + + + + + + + + +
>      >
>      > Gunnar Hellström
>      > Omnitor
>      > [e-mail]
>      > [phone]
>      
>      
>
-- 

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Gunnar Hellström
Omnitor
[e-mail]
[phone]