[Tzdist] AD review of draft-ietf-tzdist-caldav-timezone-ref-03
Barry Leiba <barryleiba@computer.org> Tue, 21 July 2015 12:36 UTC
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From: Barry Leiba <barryleiba@computer.org>
To: draft-ietf-tzdist-caldav-timezone-ref@ietf.org
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Subject: [Tzdist] AD review of draft-ietf-tzdist-caldav-timezone-ref-03
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Please excuse the delay in my review of draft-ietf-tzdist-caldav-timezone-ref. I do have some comments/questions. I'd like to discuss the questions before I request last call on the document. Please change all uses of "Prefer header" to be "Prefer header field" (Sections 3.1.3, Section 4 bullets 1 and 2). -- Section 3.1.3 -- Observation and experiments have shown that, in the vast majority of cases, CalDAV clients have typically ignored time zone definitions in data received from servers, and instead make use of their own "built- in" definitions for the corresponding time zone identifier. This means that it is reasonable for CalDAV servers to unilaterally decide not to send "VTIMEZONE" components for standard time zones that clients are expected to have "built-in" (i.e., IANA time zones). Thus, in the absence of an explicit "vtimezone=yes" or "vtimezone=no" preference in the request from a client, servers advertizing the "calendar-no-timezone" capability MAY opt to not send standard "VTIMEZONE" components. Two points about this: 1. This breaks clients (the small minority, I guess, yet they've been compliant until now) that do *not* behave this way, and expect, as has been required until now, that the VTIMEZONE components will be there. Did the working group explicitly discuss that and decide that it's OK to break them? Can someone point me to that discussion so I can give it a scan? 2. It might be best if, because of this change to the normal behaviour of CalDAV, this document would "update" 4791 (which could at least somewhat mitigate point 1). No? Should we discuss this? -- Section 4 -- Bullet 1: In this case, clients MUST retrieve the missing standard time zone definitions from the set of time zone distribution servers advertised by the CalDAV server (see Section 3.1.2). Did the working group discuss the possibility that the client has tzdist servers configured, and might prefer to use them insted? (Perhaps, for example, there are network-local tzdist servers that the client knows about, while the server's tzdist sources are network-remote.) Bullet 2: Clients can include an HTTP "Prefer" header with a "vtimezone=yes" preference to ensure that the CalDAV server does include all "VTIMEZONE" components in any iCalendar data returned in a response (see Section 3.1.3). But this doesn't "ensure" it: the HTTP Prefer header field "is used to indicate that particular server behaviors are preferred by the client but are not required for successful completion of the request." The server is allowed to fail to honor the preference. Is that a problem? Should the document address that? -- Barry, ART Director
- [Tzdist] AD review of draft-ietf-tzdist-caldav-ti… Barry Leiba
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Eliot Lear
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Cyrus Daboo
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Barry Leiba
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Ken Murchison
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Michael Douglass
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Eliot Lear
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Cyrus Daboo
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Cyrus Daboo
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Ken Murchison
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Barry Leiba
- Re: [Tzdist] AD review of draft-ietf-tzdist-calda… Eliot Lear