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HTTP (Active WG)
Art Area: Barry Leiba, Adam Roach, Alexey Melnikov | 2007-Oct-23 —  

IETF-85 httpbis minutes


These are also available from the materials page:
Server-Oriented Ranges
Upgrade-Based Negotiation
HTTP Header Encoding Results
HTTP/2.0 Compression
Flow Control Principles for HTTP 2.0
Session 2012-11-05 1300-1500: Salon D - Audio stream - httpbis chatroom
Session 2012-11-06 0900-1130: Salon E - Audio stream - httpbis chatroom


minutes-85-httpbis minute

          HTTPbis IETF85 Minutes
          Session I
          WG status
          no bashing
          Change overview
          -21 drafts are out and in LC
          overview of changes made in the latest draft (substantial only)
          no feedback on the changes that were made in the -21 drafts
          ACTION: mnot to create a ticket for https caching exception
          Security Properties
          mnot raised the issue of security properties of http and the current
          status of the draft (draft-ietf-httpbis-security-properties-05)
          barry leiba: not sure that this has any correspondence to reality; if
          we adopted something better than basic then we would not need this
          (according to S Farrell); not sure what this really has to say
          mnot: it needs to more specific if it is to be useful, which limits its
          lifetime. This is a product of a bygone era, and we might not have the
          expertise to finish this sort of work, regardless of the merits of
          security as a goal
          bleiba: suggested that this be moved to the new authentication bof and
          resulting wg
          =JeffH: did this as a measure of charity; there might be people who can do
          this within this group; i may not have time to continue this myself
          bleiba: murray will do it
          roy fielding: we haven't added all the security considerations
          mnot: are there missing considerations for the broader web
          rf: there are http considerations, but those should be in http
          documents; if there is anything left, then we can look at that
          jh: there is a lot of good stuff that should be written down; but I
          haven't done the gap analysis
          eliot lear: I agree with the chair that you need implementor interest,
          no matter where the work is done.  Is there that interest?
          mnot: there might be some stuff from here that belongs in drafts, but
          some is clearly out of scope
          el: please put it to bed
          bl: this predates our existing security considerations, which may be
          adequate now
          sean turner: this would be good to have and it is part of the charter
          bl: can you (st) read this and make a recommendation to the group?
          mnot: obviously web security has problems, but whatever we produce has
          to have some relevance
          st: you can force the issue by going to last call; or set a time limit
          for "put up or shut up"
          mnot: it's still pretty draft-y
          Other LC Documents
          rf: last call comments thus far received should take only a short time to
          rf: concerned about the lack of review in p5
          mnot: jreschke is expecting to go to proposed standard and to move to full
          standard once we've gone through the http/2 process and discovered all the
          mnot: can we go full standard?
          alexey melnikov: no
          active issues
          jr: (most of these arefrom Dan Winship's review of p1; I haven't
          entered those for p2 yet)
          rf: do we allow some leniency
          mnot: this could just be statements of fact
          rf: ok
          mnot: do we have other requirements around connection: close ?
          mnot: it could be prose
          ACTION: make SHOULD statements on Connection header handling prose
          instead of 2119 language
          ### 397
          ACTION: put the exception for OPTIONS request to a proxy and the
          resulting URI
          ### 22
          just tbd, no real issue
          ### 350
          mnot: we can close this one
          ### mnot's WGLC p1 review
          rf: asks for fresh eyes over the drafts
          mnot: asks about what is specific to HTTP as opposed to HTTP/1.1; what
          can we do to improve the way that this could be made reusable for
          no conclusion
          #### What are the parsing requirements for obs-fold with respect to
          the MUST?
          rf: if you can find no interoperable folding implementations, then we
          can remove it from the grammar [[scribe: may not have got this right,
          action more important to capture]]
          ACTION: mnot to run some tests on folding to understand its
          #### shared caching on https
          rf: the statement in question only applies to agent-side
          intermediaries and user agents, not to content accelerators, which are
          part of the origin server
          rf: some user agents use a common interface to make the request, then
          have separate logic to decide how that information is made available
          to other users
          rf: to know whether it is safe to send to other servers, you have to
          know the content
          mnot: you can use Cache-Control
          ...some disagreement here
          roberto peon: there are transformative intermediaries; we don't need to
          specify this
          mnot: need to know who this applies to
          rf: this applies to libraries in clients
          mnot: segregation... a shared cache can even apply to the same box
          martin t: 'never "public"' contradicts what has been said about caching
          paul leach: override
          Patrick McManus: on a phone, different apps can share the same network
          ACTION: follow up on this issue
          ### on US-ASCII or a superset of it
          mnot: moving on
          ### on whitespace between start-line and headers
          rf: I thought there was some guidance on this
          mnot: we should find that text
          rf: S19 should not have had any normative requirements in it
          mnot: we can remove this then
          mnot: think about consolidating the list construction rules that are
          specifically called out for Transfer-Coding
          rf: this defines the framing and more explicit rules were asked for
          mnot: ok
          ### for render as complete or consider as complete
          kevin falk: are you prohibited from using particular code blocks to users?
          rf: the important consideration is that the user is able to learn that the
          information is incomplete
          julian r: that is getting ignored in practice
          brian smith: we (Mozilla) ignore this requirement, pages are already
          mnot: would it be OK to show status in the web console?
          rf: not really
          bs: there are UX considerations that make this more difficult than it
          would appear
          bs: there's not much difference between XHR and the render as HTTP clients
          jr: we could add an indicator
          ted hardie: visual indicators are not necessarily universally applicable
          rpeon: there is a lot of confusion stemming from this statement,
          prefer the parenthetical
          bsmith: no idea about how XHR works, though it does have streaming
          modes; script developers are important
          will chan: chrome ux people didn't like the idea of having something
          in chrome
          rf: this is a safety/security feature
          kfalk: incomplete !== error
          julian: there is a related issue about truncated *downloads* (as in
          "save as"); Eric Lawrence once blogged about it
          pmcm: rathole, we (Moz) do very little prescribed error handling and
          it's strange spending time on this when there are many others; tried
          to rollback rendering when MD5 sum failed, got immense push back
          mnot: maybe this should be prose
          ACTION: Roy to make this prose text in the security considerations
          #### whitespace tolerance in headers and the requirement
          to product a 400 when the message doesn't match the grammar
          #### no enumeration for the hop-by-hop headers that are not required to be
          added to Connection header.
          rf: this will be forwarded if they aren't in the connection header;
          having a list would cause problems with intermediaries that pass these
          mnot: this could surprise some people and should be called out
          rf: this should be noted as a change from 2616
          jr: we already have this
          mnot: we probably need a callout for this one
          rf: I'm trying to reduce the number of occurences of this; they don't
          help the people reading the document for the first time
          Server Ranges
          mnot: this doesn't really mess with semantics, it only messes with
          intermediaries to the extent that range requests are hard to do anyhow
          mnot: streaming and ranges require the complete size to be known,
          changing the length would not be possible
          kfall: that is not part of the proposal
          pleach: does this work with unmodified implementations?
          kfall: not known
          pleach: profile...
          mtho: prefer might help to signal (all/some)
          mnot/kfall: makes sense
          bsmith: if the server provided less, would we be able to render it?
          the spec seems arranged around the idea of a "complete message", this
          might need to be re-addressed
          mnot: disagree, this should be addressed and if you can find something
          that isn't, please bring it up
          rf: yes
          kfall: what now?
          rf: how much testing have you done with clients that expected the bits
          that they requested?
          kfall: that's in part why we asked
          rf: testing first might determine how to proceed with this, if this
          kills an existing client, then this is a no-go
          mnot: 206 is close enough
          mnot: mumble, mumble, vary...
          rf: vary isn't so relevant in this case, it's for selecting
          mnot: fine
          ACTION: kfall to review -p5
          A not-dumb Vary header
          roy outlines the idea that you can make a request without headers to
          avoid the fingerprinting thing, detect the variances that might occur,
          then make more requests
          cyrus daboo: key == too generic
          roy: I don't care if its confusing, and number of bytes on the wire
          jr: application/*+json, globbing conneg
          roy: no, breaks stuff
          Session II
          ticket #385: upgrade mechanism
          ### TLS Upgrade for HTTPS URIs
          See thread rooted here:
          mnot will send the message suggested in that above message to the
          tls chairs
          and show up in the TLS session this afternoon
          ### Upgrade for HTTP URIs
          Gabriel M. is going to present on upgrade-based negotiation for
          http/2.0 --
          which is one approach to addressing the issues in the "http uris"
          section of
          the issues outlined in the
          roy at mike: don't need to prefix the header fields; they're just
          header fields
          mnot: it's side channel info, for optimizing
          roy: as soon as sent in http1.1 they're just a header field, register
          don't need prefix
          jhil: would those http2 things get stripped out?
          gabriel m (gm): yes
           mic: have any tests been run to confirm viability in the wild? as
          presented before, data shows port 80 has trouble with non-http1.1
          or do we just want to ignore that?
          mnot to mike belshe (mb) -- we're getting there
          gm @mic:
          phb@mic: 1st thing is successful upgrade, 2nd thing is what to do if
          it fails
          jhil: is there a timing issue with expect 100 continue ?
          mnot: do an upgrade and combine with expectation?
          roy: wouldn't normally do that. the 1st request you make shouldn't be
          a large
          state changing operation
          roy: so you send options or GET first (so it's not a packet loss issue)
          jhil: so perhaps need note about that in spec
          mnot: discussion we need to have is whether a upgrade like this is
          for us -- in hybi they figured that about 70% conns using this would be
          successful, rest would fail
          fielding: you don't upgrade a request while sending a large body and
          100-continue -- it is simply not a use case that is relevant. It
          might work
          quite well, but it simply isn't worth being concerned about.
          mnot: so perhaps deploying using this it'd encourage the internet
          to upgrade,
          but only if we have fast failure fallback
          patrick mcmanus (pm) @mic : in FF, doing 6455 (?) the TLS success
          rates are
          substantially better than the plain success rates. Roughly 80% with
          TLS, maybe
          almost 70% with plain HTTP
           mic: what did success mean in this case?
          salvatore@mic: its true we had not so good success rate with plain
          but lots of boxes will be upgraded, and they (?) just relaeased boxes with
          spdy support and [we'll see what happens (?)]
          mnot: there'll be several versions of the protocol out there because we're
          going to try various approaches
          mnot: the upgrade mech needs certain capabilities, eg supporting
          use of TLS
          mnot: calling for data on how upgrades are working -- with data we
          have now,
          it seems if we design this thing well it';ll either succeed or fail
          fast ----
          wondering about what folks thing whegther we should go down "this path"
           mic: should pursue this path, but need more data.
          pm: let's talk about the other approaches
          mnot: ok, another approach is "Using a SRV (or other DNS) record" (from
          mnot: have heard that there is general interest in using DNS as a mech,
          and do
          folks think we shouldn't use SRV?
           Mic: NOT in favor of SRV.
          ekr: this is 1st time mention srv, realise that the TLS server id check
          you do
          is with name you started with, not with the one srv gives you
          mnot: yes
           Mic: What are the goals? Please be specific!!
           mic: is there a serious proposal around srv? or is this at the
          brainstorm stage?
          mnot: we're at the brainstorm stage
          cyrus d (cd) @mic: i get http://example.com and running http/2 on that,
          but on
          example.com:88 running http/1 ....
          pm: if uri contains port, then we're not going to do the srv lookup (?)
          phb@mic: the dns is where u make assns re names; should bind names &
          prots "in
          dns"; there's practical issues with doing this; in how clients use
          dns; don't
          nec use srv; want to use dnssec; so going to use "new dns" world anyway;
          so may want srv+
          pm: this is more work everywhere, u can set this up; and so in one
          round trip
          get all info u need, can mux with this btwn http 1 & 2 and whatever,
          so this approach gives some nice benefits
          ? @mic: if u get a diff port from srv, do you use that?
          mnot: there's a lot sec related concerns here need to be careful
          eric nygren (en): having srv records would be an advantage; addtnl
          benefit is
          having sep servers handling http/1 and http/2 -- help deployment
          mnot: inclined to say this (srv/dns stuff) will be a work item for us
          mnot: upgrade mech should start in main draft ...3d mech " 2) Using
          a response
          header to hint that HTTP/2 is available on another port" from
           ted: there are still often many different http servers running on
          different ports of the same host
          Martin Thomson: Enumeration is: TLS nextproto, HTTP upgrade, srv or
          other DNS
          record, alternate-protocol header
          mnot: start developing DNS based, and a response header based mechanism as
          well. Selected editors for core HTTP work, Martin Thompson, Aleksy
          and Julian Resshke will be helping out
          Eliot Lear: I volunteer to develop at least one DNS-based proposal
          mnot: don't want to put all work on them
          header compression
          Herve Ruellan slides on HTTP Header Encoding Results
          jhil: think about impact on mobile devices such as power required ?
          agl @mic: so now spdy compression has issues with trying to avoid
          crime attack
          rp: but its still useful as baseline
          mnot: see github.com/http2/http_samples - this is a corpus of header
          har files from pcap captures.
          cd: what about webdav et al?
          mnot: if you want to submit traces for that, please do
          jhil: prob need some enterprise traces because of strange cross-domain
          we see, but need to anon them
          mnot: ... but not concerned about pathological cases
          jhil: but might help show which compress scheme is better
          mnot: next thing come up with script that analyses this stuff, and eg
          can emit
          a pathological case, and then run compression algs on it and see how
          it works
          rp: can do this in python & work with mnot
          roy: http2 is not a minor hack -- need to do it carefully -- perhaps
          we should
          have better encoding for header fields, eg cookies are huge, this could be
          binary, if we define an encoding, then can encode cookies when sending
          http and get diff comp results
          mnot: we can define new headers that have diff encodings eg binary,
          and then
          downgrade them to eg txt when sending over http/1
          roy: a cook header field, obviously can't change that due to existing
          browsers, but browsers just store it and replay it; new thing doesn't
          have to
          be compat with existing cookies, so if svr has choice to send short cook
          rather than long one....
          mnot: two diff things here, one is http1  http/2  http/1 w/o loss;
          the other is doing stuff in http/2 that are new ( and then needing to
          downgrade new stuff into http/1 as nec )
          mnot: if u can compress a bunch of requests down to fit in one underlying
          then that's very powerful, esp in mobile world; inclined to keep that
          in mind
          when selecting compression approach; .need to keep memory & cpu & power
          overheads in mind
          rp @mic: web app developers shouldn't have to opt their site to "make
          it fast"
          -- rather should make protocol fast
          mnot: yes
          phb: what about patent issues in compression?
          mnot: they'll have to disclose
          phb: if u make disclosure call now it has implications down the road
          mnot: we'll deal with that later
          mnot: we prob won't choose perfect comp mech for all time, thus negotiate
          mnot: if upgrade mech is adequate, then can include comp mech in that,
          but if
          too much optionality there, that's interop probs
          mnot: would be nice if can put it into debug mode to see stuff on wire
          -- so
          question to be able to turn comp on/off ?; .thoughts on this?
          rp: perhaps can put stuff in there to make debugging "easy" rather than
          it off"
          mnot: roberto wants to talk about http/w compression
          roy: yes, the compression ratio gets better if you send garbage on
          the wire
          roy: notes that a fixed id space is essentially a registry in machine
          rp: yes; but its not a reg that needs to be maintained after its created
          martin thompson (mt): dont understand where huffman encoding comes
          into play?
          rp: draft needs work; what is huffman coded is the text in the
          headers. ran
          analysis over sample of headers, and then used that to gen id space
           seems to me that we are maybe doing this the wrong way
          rp: hopefully impl code for this is better to understand than the I-D
          at this
          point :)
          mnot: so we know sorta where we going on compression stuff, want to
          get impls
          plugged into the http2 namespace on github -- the more visible we can make
          this the better
           the question was: do you have a note well on the repo
          #387: server push
          We need more data / experience.
          Other Issues
          ### Flow Control
          gabriel montenegro (gm) -- flow control principles for http 2
          hildjj: we need TSV help for this part.
          roy: init exchange over tcp, client begins; with this do you expect
          server to
          send anything first wrt state?
          gm: in spdy there's default 64k per stream
          rp: basically need default for safety reasons, but a better FC mech
          than spdy3
          exists, hopefully will be proposed, can make larger than 64k by defualt
          ted hardie(th): what impact if doing multipath tcp under this?
          gm: yes need to figure out interaction with newish tcp stuff under it
          mnot: is FC tightly bound to what xport's properties are?
          gm: yes
          jhil: we need early involvement by transport folks, don't wanna make
          bloat worse
          rp: don't think that's possible
          will chan (wc): would hope that FC in http/2 doesn't subvert xport FC;
          want to
          make sure we saturate link; this should be one of the principles
          gm: thinks link saturation depends on how the
          work; don't have to solve now
          alison mankin (am): if receiver has FC turned off by intermediary,
          that messes
          stuff up.
          gm: but receiver controls it for his hop. is concerned about middleboxes
          http layer; at that layer the proxy has to heed what endpoint (receiver)
          wishes. still concerned on traps that may be there
          rp: there's finite buffering available for entire path length; if receiver
          says stop, it'll stop eventually; but as soon as an intermediate is in the
          path, they have influence on FC
          gm: we need to codify the rules in the base spec
          mnot: gm will have draft coming out, please review. FC will get a new
          issue #
          ### Priorities
          pm: priorities need discussion
          mnot: will create issue for that (framing, diff frame sizes)
          rp: want to agree and disagree wrt priortzn stuff -- need more
          mnot: sure, may defer disc of these issues, but want to get em written
          ### Mapping to TCP
          eric nygren (en): mapping to tcp -- need to disc
          mnot: yes, need optional draft on "how i use tcp"
          rp: agree with en that'll be issue, might wanna address earlier, need
          to get
          sec folk thinking about that
          en: also has implications for prototcol upgrade mech, signalling may
          make this
          easier or harder
          ### Framing
          gm: did u raise issue on framing itself?
          mnot: it will get raised; specific concern; useful for e.g., sendfile()
          mnot: am gratified to see folks working on drafts; continue doing that;
          use wiki to record current state of proposals; interlink to issue #s; will
          also use github; will hand out access to (sub) repositories; the actual
          will be in ietf subversion service;
          mnot: f2f meetings are effective for work like this, involves lots
          of folks,
          need to confirm decisions on list, tho possiblities of interim meetings,
          be good idea here in earlier phase like this, current plan is interim
          mtg in
          Jan 2013, 2..3 days, offer from Ian Fette to host in Tokyo, need to
          get dates,
          maybe mid Jan to early Feb, pls send dates ideas to mnot
          mnot: any more biz ?
          phb: discussing compression -- was of msgs, not conversations -- in
          mobile --
          sending "pages" with lists of links --- but maybe do html-conscious
          compression ?
          jhil: don't we get some of that with svr push?
          en: if start with http1, include an encoded blob of handshake framing?
          mnot: that's in category of cool tricks we could play.
          mnot: keep drafts coming, will send minutes out soon, if hold this interim
          mtg, want to make it useful

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