Re: [salud] Christer's review of draft-ietf-salud-alert-info-urns-09
Laura Liess <laura.liess.dt@googlemail.com> Thu, 23 January 2014 19:20 UTC
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References: <7594FB04B1934943A5C02806D1A2204B1C5EF0E7@ESESSMB209.ericsson.se> <201401072131.s07LVQZs2347719@shell01.TheWorld.com> <7594FB04B1934943A5C02806D1A2204B1C5F00D5@ESESSMB209.ericsson.se> <201401162107.s0GL7AKI2944531@shell01.TheWorld.com> <7594FB04B1934943A5C02806D1A2204B1D108F92@ESESSMB209.ericsson.se> <CACWXZj033ssRvpJPQ=V8LACYUW9SpySbf+Pi86XR6eu5YWmdcw@mail.gmail.com> <7594FB04B1934943A5C02806D1A2204B1D11179F@ESESSMB209.ericsson.se> <CACWXZj33UCV7miz4FE=SHnmaPp0BdpZCR3b3bh8AZxjv0ruCug@mail.gmail.com> <7594FB04B1934943A5C02806D1A2204B1D1120FE@ESESSMB209.ericsson.se> <CACWXZj2z536sqHgc3iRZrr5XXFZs9c8Dv6JgK3RUS1GM_12kUQ@mail.gmail.com> <7594FB04B1934943A5C02806D1A2204B1D115ED0@ESESSMB209.ericsson.se> <CACWXZj0epir54mjRAvtZvE8JXngWn=FQiYV7G8JBnNQ31_89Xg@mail.gmail.com> <7594FB04B1934943A5C02806D1A2204B1D1193A1@ESESSMB209.ericsson.se>
Date: Thu, 23 Jan 2014 20:20:10 +0100
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From: Laura Liess <laura.liess.dt@googlemail.com>
To: Christer Holmberg <christer.holmberg@ericsson.com>
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Cc: "salud@ietf.org" <salud@ietf.org>
Subject: Re: [salud] Christer's review of draft-ietf-salud-alert-info-urns-09
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Christer, Thank you. I will do so. Laura 2014/1/23 Christer Holmberg <christer.holmberg@ericsson.com> > Hi Laura, > > I think the update section should come AFTER the ‘Requirements Language’ > and ‘Terminology’ sections. Otherwise it looks good. > > Regards, > > Christer > > Sent from Windows Mail > > *From:* laura.liess.dt@googlemail.com > *Sent:* Thursday, January 23, 2014 1:42 PM > > *To:* Hans-Christer Holmberg <christer.holmberg@ericsson.com> > *Cc:* salud@ietf.org > > Hi Christer, > > please find below the new text which incorporates, for my understanding > the changes around your comments Q1 to Q5. I also attached the intermediary > version of the draft incorporating these comments so you can use the > rfcdiff tool. > > I had a look at the draft recently approved by the IESG (status > "publication required") and it seems to me that there are no requirements > concerning the structure. > > Please let me know if this is OK for you or not. > > Thank you > Laura > > 1. Introduction > > The Session Initiation Protocol (SIP) [RFC3261] includes a means to > suggest to a user agent (UA) a particular ringback tone or ring tone > to be used during session establishment. In [RFC3261] this is done > by including a URI in the Alert-Info header field, that specifies the > tone. The URI is most commonly the HTTP URL to the audio file. On > the receipt of the Alert-Info header field the user agent may fetch > the referenced ringback tone or ring tone and play it to the user. > > This mechanism hinders interoperability when there is no common > understanding of the meaning of the referenced tone, which might be > country- or vendor-specific. It can lead to problems for the user > trying to interpret the tone and for the UA wanting to substitute its > own tone (e.g., in accordance with user preferences) or provide an > alternative alerting mode (e.g., for hearing-impaired users). If > caller and callee are from different countries, the understanding of > the tones may vary significantly. Hearing impaired users may not > sense the specific tone if it is provided as an audio file. The tone > per se is also not useful for automata. > > Another limitation of using URLs of audio files is that the > referenced tones are tied to particular renderings. It is not > possible to provide semantic indications or names for rendering > characteristics that signal the intent and allow the recipient UA to > decide how to render the received information in an appropriate way. > > The issues with URLs that reference audio files can be avoided by > using fixed URLs with specific meanings. However this approach has > its own interoperability issues. For example, consider the PBX > special ring tone for an external (to the PBX) caller. Different > vendors use different approaches such as: Alert-Info: > <file://ring.pcm>;alert=normal where ring.pcm is a dummy file or: > Alert-Info: <file://normal.ring.pcm> or: Alert-Info: > <sip:normal-ringtone@example.com>. As a result, the Alert-Info > header field currently only works when the same vendor provides PBX > and UA, and only then if the same "fake" proprietary URI convention > used. > > To solve the described issues, this specification defines the new URN > namespace "alert" for the Alert-Info header field that allows for > programmatic user interface adaptation and for conversion of > equivalent alerting tones in the Public Switched Telephone Network > (PSTN) when the client is a gateway. The work to standardize an > "alert" URN will increase SIP interoperability for this header field > by replacing proprietary conventions used today. > > Using the "alert" namespace provides syntax for several different > > > > Liess, et al. Expires July 27, 2014 [Page 5] > > > Internet-Draft Alert URNs January 2014 > > > application spaces, e. g.: > > o Names for service indications, such as call waiting or automatic > callback, not tied to any particular rendering. > o Names for common ring tones generated by PBX phones for cases such > as an internal enterprise caller, external caller, ringback tone > after a transfer failure or expiration of a hold timer, etc. > o Names for country-specific ringback tones. > o Names for things with specific renderings that aren't purely > audio. They might be static icons, video sequences, text, etc. > > Some advantages of a URN rather than a URL of a downloadable > resource: > > o Do not need to download it or deal with security issues associated > with dereferencing. > o No formatting or compatibility issues. > o No security risk of rendering something unexpected and > undesirable. > o The tone can be stored locally in whatever format and at whatever > quality level is appropriate, because it is specified "by name" > rather than "by value". > o It is easier to make policy decisions about whether to use it or > not. > o It facilitates translation for the hearing impaired. > > The downside is that if the recipient does not understand the URN > then it will only be able to render a default ringback tone or ring > tone. > > This document creates a new URN namespace and registry for alert > indications and registers some initial values. > > In practice, this specification extends the usage of the Alert-Info > header field in that it will cause the use of a new class of URIs and > the use of multiple URIs. Backward compatibility issues are not > expected, as devices that do not understand an "alert" URN should > ignore it, and devices should not malfunction upon receiving multiple > Alert-Info header field <alert-param>s (which was syntactically > permitted before, but rarely used). > > > 2. Update to RFC 3261 > > 2.1. General > > This specification changes the usage of the Alert-Info header field > defined in the [RFC3261] by additionally allowing its use in all > > > > Liess, et al. Expires July 27, 2014 [Page 6] > > > Internet-Draft Alert URNs January 2014 > > > provisional responses to INVITE (except the 100 response). > > Previously, the Alert-Info header field was only permitted in 180 > (Ringing) responses. But in telephony, other situations indicated by > SIP provisional responses, such as 181 (Call Is Being Forwarded) and > 182 (Call Is Being Queued), are often indicated by tones. Extending > the applicability of the Alert-Info header field allows the telephony > practice to be implemented in SIP. > > 2.2. New text replacing the text of the 1st paragraph of section 20.4 > of RFC 3261 > > When present in an INVITE request, the Alert-Info header field > specifies an alternative ring tone to the UAS. When present in a > non-100 provisional response, the Alert-Info header field specifies > an alternative ringback tone to the UAC. A typical usage is for a > proxy to insert this header field to provide a distinctive ring > feature. > > > 3. Requirements Language > > The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", > "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this > document are to be interpreted as described in [RFC2119]. > > > 4. Terminology > > This specification uses a number of terms to refer to the roles > involved in the use of alerting indications in SIP. A "specifier" > sends an "alerting indication" (one or more URNs in an Alert-Info > header field) to a "renderer" which then "renders" a "signal" or > "rendering" based on the indication to a human user. A "category" is > a characteristic whose "values" can be used to classify indications. > > This specification uses the terms "ring tone" and "ringback tone". A > "ring tone" or "calling signal" (terminology used in [E182]) is a > signal generated by the callee's end device, advising the callee > about an incoming call. A "ringback tone" or "ringing tone" > (terminology used in [E182]) is a signal advising the caller that a > connection has been made and that a ring tone is being rendered to > the callee. > > > > > 2014/1/23 Christer Holmberg <christer.holmberg@ericsson.com> > >> Hi Laura, >> >> Could you please put the text in an e-mail, how it would look? >> >> Regards, >> >> Christer >> >> Sent from Windows Mail >> >> *From:* laura.liess.dt@googlemail.com >> *Sent:* Wednesday, January 22, 2014 3:39 PM >> >> *To:* Hans-Christer Holmberg <christer.holmberg@ericsson.com> >> *Cc:* salud@ietf.org >> >> >> >> >> 2014/1/21 Christer Holmberg <christer.holmberg@ericsson.com> >> >>> Hi, >>> >>> In my opinion, the normative update (no matter how is done), should >>> not be in section 1, which is introduction. >>> >>> It shall of course be mentioned there, but I still think there should >>> be a dedicated “Update to RFC 3261” section. >>> >> That is what I intend to do. New Section 2 "Update to RFC 3261", exactly >> as you proposed with the subsections 2.1 "General" and 2.2 "New text >> replacing ....". >> My question is about the content of the subsection 2.1 "General". The >> current section 1.2 contains three paragraphs. I propose to put into 2.1 >> only the first two paragraphs from the current 1.2 and to move the third >> paragraph to section 1.1 because this paragraph does not describe an update >> of the 3261. Would you agree with this change? >> >> Thank you >> Laura >> >> >> Regards, >>> >>> Christer >>> >>> Sent from Windows Mail >>> >>> *From:* laura.liess.dt@googlemail.com >>> *Sent:* Tuesday, January 21, 2014 3:30 PM >>> *To:* Hans-Christer Holmberg <christer.holmberg@ericsson.com> >>> *Cc:* salud@ietf.org >>> >>> Hi Christer, >>> >>> thank you. What about moving the third paragraph to subsection 1.1? >>> Could this work for you? >>> >>> Laura >>> >>> >>> 2014/1/21 Christer Holmberg <christer.holmberg@ericsson.com> >>> >>>> Hi Laura, >>>> >>>> SIPCORE some time ago decided not to use/maintain the header field >>>> tables anymore, so that is why I didn't include it in my change suggestion. >>>> >>>> But, if you want to also change the table, I won’t object 😊 >>>> >>>> Regards, >>>> >>>> Christer >>>> >>>> Sent from Windows Mail >>>> >>>> *From:* laura.liess.dt@googlemail.com >>>> *Sent:* Tuesday, January 21, 2014 12:54 PM >>>> *To:* Hans-Christer Holmberg <christer.holmberg@ericsson.com> >>>> *Cc:* Dale R. Worley <worley@ariadne.com>, salud@ietf.org >>>> >>>> Christer, Dale, >>>> >>>> IMO, the draft updates the RFC 3261 because it allows the usage of the >>>> Alert-Info header field in all provisional responses 1xx except the 100 >>>> response. This is described in the first two paragraphs of Section 1.2. >>>> This paragraphs are OK in this section. >>>> The third paragraph is usefull (it explains what the draft does) but, >>>> as Christer remarked, it does not describe the update of the RFC3261 and >>>> so it does not belong to this section. I would move this paragraph at the >>>> end of Section 1.1. What do you think? >>>> >>>> Concerning the structure if the Section 1.2, I will put the text >>>> from section 1.2 into a new main Section 2 and structure it as Christer >>>> proposes in >>>> http://www.ietf.org/mail-archive/web/salud/current/msg00454.html. >>>> But I think there are two places where we should update the 3261 text: >>>> 1) Section 20.4 as proposed by Christer and >>>> >>>> 2) Table 2: Summary of header fields, A--O on page 161, the " 180" in >>>> the row >>>> >>>> Alert-Info 180 ar - - - o - - >>>> >>>> should be changed in "1xx (excepting 100)" >>>> >>>> so we probably need two subsections "New text repalcing the >>>> text.........of RFC 3261" . >>>> Opinions? >>>> >>>> Thank you >>>> Laura >>>> >>>> >>>> >>>> 2014/1/20 Christer Holmberg <christer.holmberg@ericsson.com> >>>> >>>>> Hi, >>>>> >>>>> >> BTW, the following sentence is unclear to me: >>>>> >> >>>>> >> "In practice, this specification extends Alert-Info in that it >>>>> will >>>>> >> cause the use of a new class of URIs and the use of multiple >>>>> URIs." >>>>> >> >>>>> >> What does it mean? >>>>> > >>>>> > The idea is that, while 3261 syntactically and semantically *allows* >>>>> non-HTTP URIs in Alert-Info, nobody ever used non-HTTP URIs in Alert-Info, >>>>> and nobody implemented an interpretation of those URIs. >>>>> > Thus, even though we are not changing what is officially permitted, >>>>> implementers will have to change their code because the new *practice* will >>>>> be an extension of the old practice. (And both the new practice and the >>>>> old practice are a small subset of what is permitted by 3261.) >>>>> >>>>> Well, then you should use different wording. Because, the draft does >>>>> not extend Alert-Info, it simply describes the usage of a new URN in the >>>>> header field. >>>>> >>>>> >>>>> >>>> Q9: >>>>> >>>> ----- >>>>> >>>> >>>>> >>>> Section 4 defines the ABNF for the URN, but [there] is no text on >>>>> >>>> how to "map" it into the Alert-Info header field ABNF: >>>>> >>>> >>>>> >>>> For example, I assume that the URN is encoded using the >>>>> opaque-part >>>>> >>>> format of the absoluteURI, and that the scheme value is "urn". I >>>>> >>>> think it would be good to indicate that. >>>>> >>> >>>>> >>> Actually, we're depending on the fact (unstated in RFC 3261) that >>>>> >>> any "absolute" URI (per RFC 3986) is allowed as a header field >>>>> value >>>>> >>> in Alert-Info, and that the URNs we are defining conform to the >>>>> >>> absolute URI syntax. If the syntax for <absoluteURI> in RFC 3261 >>>>> >>> didn't allow all absolute URIs, we'd have to amend RFC 3261. >>>>> >> >>>>> >> There are two different "structures" for absolute URI, and the URNs >>>>> >> only fit into the opaque-part structure. >>>>> >> >>>>> >> In addition, as the URI requires a scheme value, I think we should >>>>> >> explicitly say what it is. >>>>> > >>>>> > I guess my point is that the 3261 ABNF already allows all alert URNs >>>>> to appear in Alert-Info, and there is no need to specify exactly how alert >>>>> URNs are compatible with the 3261 ABNF. Anyone who cares exactly how this >>>>> draft is directly compatible with the ABNF can see that by looking at the >>>>> ABNF. >>>>> > >>>>> > Have there been other situations where this sort of syntax >>>>> explication has been provided? >>>>> >>>>> I don't know - I am just commenting on how I think the draft could >>>>> from my perspective be improved :) >>>>> >>>>> Regards, >>>>> >>>>> Christer >>>>> _______________________________________________ >>>>> salud mailing list >>>>> salud@ietf.org >>>>> https://www.ietf.org/mailman/listinfo/salud >>>>> >>>> >>>> >>>> _______________________________________________ >>>> salud mailing list >>>> salud@ietf.org >>>> https://www.ietf.org/mailman/listinfo/salud >>>> >>>> >>> >> >
- [salud] Christer's review of draft-ietf-salud-ale… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Dale R. Worley
- Re: [salud] Christer's review of draft-ietf-salud… Paul Kyzivat
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Paul Kyzivat
- Re: [salud] Christer's review of draft-ietf-salud… Dale R. Worley
- Re: [salud] Christer's review of draft-ietf-salud… Paul Kyzivat
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Laura Liess
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Laura Liess
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… DRAGE, Keith (Keith)
- Re: [salud] Christer's review of draft-ietf-salud… Laura Liess
- Re: [salud] Christer's review of draft-ietf-salud… Laura Liess
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Dale R. Worley
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Laura Liess
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- Re: [salud] Christer's review of draft-ietf-salud… Laura Liess
- Re: [salud] Christer's review of draft-ietf-salud… Christer Holmberg
- [salud] Fwd: Christer's review of draft-ietf-salu… Laura Liess
- Re: [salud] Fwd: Christer's review of draft-ietf-… Christer Holmberg