Monthly Archives: July 2016

Network, Web

A third day of deep HTTP inspection

The workshop roomThis fine morning started off with some news: Patrick is now our brand new official co-chair of the IETF HTTPbis working group!

Subodh then sat down and took us off on a presentation that really triggered a long and lively discussion. “Retry safety extensions” was his name of it but it involved everything from what browsers and HTTP clients do for retrying with no response and went on to also include replaying problems for 0-RTT protocols such as TLS 1.3.

Julian did a short presentation on http headers and his draft for JSON in new headers and we quickly fell down a deep hole of discussions around various formats with ups and downs on them all. The general feeling seems to be that JSON will not be a good idea for headers in spite of a couple of good characteristics, partly because of its handling of duplicate field entries and how it handles or doesn’t handle numerical precision (ie you can send “100” as a monstrously large floating point number).

Mike did a presentation he called “H2 Regrets” in which he covered his work on a draft for support of client certs which was basically forbidden due to h2’s ban of TLS renegotiation, he brought up the idea of extended settings and discussed the lack of special handling dates in HTTP headers (why we send 29 bytes instead of 4). Shows there are improvements to be had in the future too!

Martin talked to us about Blind caching and how the concept of this works. Put very simply: it is a way to make it possible to offer cached content for clients using HTTPS, by storing the data in a 3rd host and pointing out that data to the client. There was a lengthy discussion around this and I think one of the outstanding questions is if this feature is really giving as much value to motivate the rather high cost in complexity…

The list of remaining Lightning Talks had grown to 10 talks and we fired them all off at a five minutes per topic pace. I brought up my intention and hope that we’ll do a QUIC library soon to experiment with. I personally particularly enjoyed EKR’s TLS 1.3 status summary. I heard appreciation from others and I agree with this that the idea to feature lightning talks was really good.

With this, the HTTP Workshop 2016 was officially ended. There will be a survey sent out about this edition and what people want to do for the next/future ones, and there will be some sort of  report posted about this event from the organizers, summarizing things.

Attendees numbers

http workshopThe companies with most attendees present here were: Mozilla 5, Google 4, Facebook, Akamai and Apple 3.

The attendees were from the following regions of the world: North America 19, Europe 15, Asia/pacific 6.

38 participants were male and 2 female.

23 of us were also at the 2015 workshop, 17 were newcomers.

15 people did lightning talks.

I believe 40 is about as many as you can put in a single room and still have discussions. Going larger will make it harder to make yourself heard as easily and would probably force us to have to switch to smaller groups more and thus not get this sort of great dynamic flow. I’m not saying that we can’t do this smaller or larger, just that it would have to make the event different.

Some final words

I had an awesome few days and I loved all of it. It was a pleasure organizing this and I’m happy that Stockholm showed its best face weather wise during these days. I was also happy to hear that so many people enjoyed their time here in Sweden. The hotel and its facilities, including food and coffee etc worked out smoothly I think with no complaints at all.

Hope to see again on the next HTTP Workshop!

Network, Web

Workshop day two

2 Comments

HTTP Workshop At 5pm we rounded off another fully featured day at the HTTP workshop. Here’s some of what we touched on today:

Moritz started the morning with an interesting presentation about experiments with running the exact same site and contents on h1 vs h2 over different kinds of networks, with different packet loss scenarios and with different ICWND set and more. Very interesting stuff. If he makes his presentation available at some point I’ll add a link to it.

I then got the honor to present the state of the TCP Tuning draft (which I’ve admittedly been neglecting a bit lately), the slides are here. I made it brief but I still got some feedback and in general this is a draft that people seem to agree is a good idea – keep sending me your feedback and help me improve it. I just need to pull myself together now and move it forward. I tried to be quick to leave over to…

Jana, who was back again to tell us about QUIC and the state of things in that area. His presentation apparently was a subset of slides he presented last week in the Berlin IETF. One interesting take-away for me, was that they’ve noticed that the amount of connections for which they detect UDP rate limiting on, has decreased with 2/3 during the last year!

Here’s my favorite image from his slide set. Apparently TCP/2 is not a name for QUIC that everybody appreciates! 😉

call-it-tcp2-one-more-time

While I think the topic of QUIC piqued the interest of most people in the room and there were a lot of questions, thoughts and ideas around the topic we still managed to get the lunch break pretty much in time and we could run off and have another lovely buffet lunch. There’s certainly no risk for us loosing weight during this event…

After lunch we got ourselves a series of Lightning talks presented for us. Seven short talks on various subjects that people had signed up to do

One of the lightning talks that stuck with me was what I would call the idea about an extended Happy Eyeballs approach that I’d like to call Even Happier Eyeballs: make the client TCP connect to all IPs in a DNS response and race them against each other and use the one that responds with a SYN-ACK first. There was interest expressed in the room to get this concept tested out for real in at least one browser.

We then fell over into the area of HTTP/3 ideas and what the people in the room think we should be working on for that. It turned out that the list of stuff we created last year at the workshop was still actually a pretty good list and while we could massage that a bit, it is still mostly the same as before.

Anne presented fetch and how browsers use HTTP. Perhaps a bit surprising that soon brought us over into the subject of trailers, how to support that and voilá, in the end we possibly even agreed that we should perhaps consider handling them somehow in browsers and even for javascript APIs… ( nah, curl/libcurl doesn’t have any particular support for trailers, but will of course get that if we’ll actually see things out there start to use it for real)

I think we deserved a few beers after this day! The final workshop day is tomorrow.

cURL and libcurl, Firefox, Mozilla, Web

A workshop Monday

http workshopI decided I’d show up a little early at the Sheraton as I’ve been handling the interactions with hotel locally here in Stockholm where the workshop will run for the coming three days. Things were on track, if we ignore how they got the wrong name of the workshop on the info screens in the lobby, instead saying “Haxx Ab”…

Mark welcomed us with a quick overview of what we’re here for and quick run-through of the rough planning for the days. Our schedule is deliberately loose and open to allow for changes and adaptations as we go along.

Patrick talked about the 1 1/2 years of HTTP/2 working in Firefox so far, and we discussed a lot around the numbers and telemetry. What do they mean and why do they look like this etc. HTTP/2 is now at 44% of all HTTPS requests and connections using HTTP/2 are used for more than 8 requests on median (compared to slightly over 1 in the HTTP/1 case). What’s almost not used at all? HTTP/2 server push, Alt-Svc and HTTP 308 responses. Patrick’s presentation triggered a lot of good discussions. His slides are here.

RTT distribution for Firefox running on desktop and mobile, from Patrick’s slide set:

rtt-dist

The lunch was lovely.

Vlad then continued to talk about experiences from implementing and providing server push at Cloudflare. It and the associated discussions helped emphasize that we need better help for users on how to use server push and there might be reasons for browsers to change how they are stored in the current “secondary cache”. Also, discussions around how to access pushed resources and get information about pushes from javascript were briefly touched on.

After a break with some sweets and coffee, Kazuho continued to describe cache digests and how this concept can help making servers do better or more accurate server pushes. Back to more discussions around push and what it actually solved, how much complexity it is worth and so on. I thought I could sense hesitation in the room on whether this is really something to proceed with.

We intend to have a set of lightning talks after lunch each day and we have already have twelve such suggested talks listed in the workshop wiki, but the discussions were so lively and extensive that we missed them today and we even had to postpone the last talk of today until tomorrow. I can already sense how these three days will not be enough for us to cover everything we have listed and planned…

We ended the evening with a great dinner sponsored by Mozilla. I’d say it was a great first day. I’m looking forward to day 2!

cURL and libcurl, Mozilla, Network, Web

HTTP Workshop 2016, day -1

http workshop The HTTP Workshop 2016 will take place in Stockholm starting tomorrow Monday, as I’ve mentioned before. Today we’ll start off slowly by having a few pre workshop drinks and say hello to old and new friends.

I did a casual count, and out of the 40 attendees coming, I believe slightly less than half are newcomers that didn’t attend the workshop last year. We’ll see browser people come, more independent HTTP implementers, CDN representatives, server and intermediary developers as well as some friends from large HTTP operators/sites. I personally view my attendance to be primarily with my curl hat on rather than my Firefox one. Firmly standing in the client side trenches anyway.

Visitors to Stockholm these days are also lucky enough to arrive when the weather is possibly as good as it can get here with the warmest period through the summer so far with lots of sun and really long bright summer days.

News this year includes the @http_workshop twitter account. If you have questions or concerns for HTTP workshoppers, do send them that way and they might get addressed or at least noticed.

I’ll try to take notes and post summaries of each workshop day here. Of course I will fully respect our conference rules about what to reveal or not.

stockholm castle and ship

cURL and libcurl, Network, Web

curl wants to QUIC

The interesting Google transfer protocol that is known as QUIC is being passed through the IETF grinding machines to hopefully end up with a proper “spec” that has been reviewed and agreed to by many peers and that will end up being a protocol that is thoroughly documented with a lot of protocol people’s consensus. Follow the IETF QUIC mailing list for all the action.

I’d like us to join the fun

Similarly to how we implemented HTTP/2 support early on for curl, I would like us to get “on the bandwagon” early for QUIC to be able to both aid the protocol development and serve as a testing tool for both the protocol and the server implementations but then also of course to get us a solid implementation for users who’d like a proper QUIC capable client for data transfers.

implementations

The current version (made entirely by Google and not the output of the work they’re now doing on it within the IETF) of the QUIC protocol is already being widely used as Chrome speaks it with Google’s services in preference to HTTP/2 and other protocol options. There exist only a few other implementations of QUIC outside of the official ones Google offers as open source. Caddy offers a separate server implementation for example.

the Google code base

For curl’s sake, it can’t use the Google code as a basis for a QUIC implementation since it is C++ and code used within the Chrome browser is really too entangled with the browser and its particular environment to become very good when converted into a library. There’s a libquic project doing exactly this.

for curl and others

The ideal way to implement QUIC for curl would be to create “nghttp2” alternative that does QUIC. An ngquic if you will! A library that handles the low level protocol fiddling, the binary framing etc. Done that way, a QUIC library could be used by more projects who’d like QUIC support and all people who’d like to see this protocol supported in those tools and libraries could join in and make it happen. Such a library would need to be written in plain C and be suitably licensed for it to be really interesting for curl use.

a needed QUIC library

I’m hoping my post here will inspire someone to get such a project going. I will not hesitate to join in and help it get somewhere! I haven’t started such a project myself because I think I already have enough projects on my plate so I fear I wouldn’t be a good leader or maintainer of a project like this. But of course, if nobody else will do it I will do it myself eventually. If I can think of a good name for it.

some wishes for such a library

  • Written in C, to offer the same level of portability as curl itself and to allow it to get used as extensions by other languages etc
  • FOSS-licensed suitably
  • It should preferably not “own” the socket but also work in-memory and to allow applications to do many parallel connections etc.
  • Non-blocking. It shouldn’t wait for things on its own but let the application do that.
  • Should probably offer both client and server functionality for maximum use.
  • What else?