Tag Archives: HTTP Workshop

Mozilla, Network, Web

HTTP Workshop – London edition. First day.

The HTTP workshop series is back for a third time this northern hemisphere summer. The selected location for the 2017 version is London and this time we’re down to a two-day event (we seem to remove a day every year)…

Nothing in this blog entry is a quote to be attributed to a specific individual but they are my interpretations and paraphrasing of things said or presented. Any mistakes or errors are all mine.

At 9:30 this clear Monday morning, 35 persons sat down around a huge table in a room in the Facebook offices. Most of us are the same familiar faces that have already participated in one or two HTTP workshops, but we also have a set of people this year who haven’t attended before. Getting fresh blood into these discussions is certainly valuable. Most major players are represented, including Mozilla, Google, Facebook, Apple, Cloudflare, Fastly, Akamai, HA-proxy, Squid, Varnish, BBC, Adobe and curl!

Mark (independent, co-chair of the HTTP working group as well as the QUIC working group) kicked it all off with a presentation on quic and where it is right now in terms of standardization and progress. The upcoming draft-04 is becoming the first implementation draft even though the goal for interop is set basically at handshake and some very basic data interaction. The quic transport protocol is still in a huge flux and things have not settled enough for it to be interoperable right now to a very high level.

Jana from Google presented on quic deployment over time and how it right now uses about 7% of internet traffic. The Android Youtube app’s switch to QUIC last year showed a huge bump in usage numbers. Quic is a lot about reducing latency and numbers show that users really do get a reduction. By that nature, it improves the situation best for those who currently have the worst connections.

It doesn’t solve first world problems, this solves third world connection issues.

The currently observed 2x CPU usage increase for QUIC connections as compared to h2+TLS is mostly blamed on the Linux kernel which apparently is not at all up for this job as good is should be. Things have clearly been more optimized for TCP over the years, leaving room for improvement in the UDP areas going forward. “Making kernel bypassing an interesting choice”.

Alan from Facebook talked header compression for quic and presented data, graphs and numbers on how HPACK(-for-quic), QPACK and QCRAM compare when used for quic in different networking conditions and scenarios. Those are the three current header compression alternatives that are open for quic and Alan first explained the basics behind them and then how they compare when run in his simulator. The current HPACK version (adopted to quic) seems to be out of the question for head-of-line-blocking reasons, the QCRAM suggestion seems to run well but have two main flaws as it requires an awkward layering violation and an annoying possible reframing requirement on resends. Clearly some more experiments can be done, possible with a hybrid where some QCRAM ideas are brought into QPACK. Alan hopes to get his simulator open sourced in the coming months which then will allow more people to experiment and reproduce his numbers.

Hooman from Fastly on problems and challenges with HTTP/2 server push, the 103 early hints HTTP response and cache digests. This took the discussions on push into the weeds and into the dark protocol corners we’ve been in before and all sorts of ideas and suggestions were brought up. Some of them have been discussed before without having been resolved yet and some ideas were new, at least to me. The general consensus seems to be that push is fairly complicated and there are a lot of corner cases and murky areas that haven’t been clearly documented, but it is a feature that is now being used and for the CDN use case it can help with a lot more than “just an RTT”. But is perhaps the 103 response good enough for most of the cases?

The discussion on server push and how well it fares is something the QUIC working group is interested in, since the question was asked already this morning if a first version of quic could be considered to be made without push support. The jury is still out on that I think.

ekr from Mozilla spoke about TLS 1.3, 0-RTT, how the TLS 1.3 handshake looks like and how applications and servers can take advantage of the new 0-RTT and “0.5-RTT” features. TLS 1.3 is already passed the WGLC and there are now “only” a few issues pending to get solved. Taking advantage of 0RTT in an HTTP world opens up interesting questions and issues as HTTP request resends and retries are becoming increasingly prevalent.

Next: day two.

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

Network, Technology, Web

Summers are for HTTP

stockholm castle and ship
Stockholm City, as photographed by Michael Caven

In July 2015, 40-something HTTP implementers and experts of the world gathered in the city of Münster, Germany, to discuss nitty gritty details about the HTTP protocol during four intense days. Representatives for major browsers, other well used HTTP tools and the most popular HTTP servers were present. We discussed topics like how HTTP/2 had done so far, what we thought we should fix going forward and even some early blue sky talk about what people could potentially see being subjects to address in a future HTTP/3 protocol.

You can relive the 2015 version somewhat from my daily blog entries from then that include a bunch of details of what we discussed: day one, two, three and four.

http workshopThe HTTP Workshop was much appreciated by the attendees and it is now about to be repeated. In the summer of 2016, the HTTP Workshop is again taking place in Europe, but this time as a three-day event slightly further up north: in the capital of Sweden and my home town: Stockholm. During 25-27 July 2016, we intend to again dig in deep.

If you feel this is something for you, then please head over to the workshop site and submit your proposal and show your willingness to attend. This year, I’m also joining the Program Committee and I’ve signed up for arranging some of the local stuff required for this to work out logistically.

The HTTP Workshop 2015 was one of my favorite events of last year. I’m now eagerly looking forward to this year’s version. It’ll be great to meet you here!

Stockholm
The city of Stockholm in summer sunshine
Mozilla, Network, Open Source, Web

The last HTTP Workshop day

This workshop has been really intense days so far and this last and forth Workshop day did not turn out differently. We started out the morning with the presentation: Caching, Intermediation and the Modern Web by Martin Thomson (Mozilla) describing his idea of a “blind cache” and how it could help to offer caching in a HTTPS world. It of course brought a lot of discussions and further brainstorming on the ideas and how various people in the room thought the idea could be improved or changed.

Immediately following that, Martin continued with a second presentation describing for us a suggested new encryption format for HTTP based on the JWE format and how it could possible be used.

The room then debated connection coalescing (with HTTP/2) for a while and some shared their experiences and thoughts on the topic. It is an area where over-sharing based on the wrong assumptions certainly can lead to tears and unhappiness but it seems the few in the room who actually have implemented this seemed to have considered most of the problems people could foresee.

Support of Trailers in HTTP was brought up and we discussed its virtues for a while vs the possible problems with supporting it and what possible caveats could be, and we also explored the idea of using HTTP/2 push instead of trailers to allow servers to send meta-data that way, and that then also doesn’t necessarily have to follow after the transfer but can in fact be sent during transfer!

Resumed uploads is a topic that comes back every now and then and that has some interest. (It is probably one of the most frequently requested protocol features I get asked about.) It was brought up as something we should probably discuss further, and especially when discussing the next generation HTTP.

At some point in the future we will start talking about HTTP/3. We had a long discussion with the whole team here on what HTTP/3 could entail and we also explored general future HTTP and HTTP/2 extensions and more. A massive list of possible future work was created. The list ended up with something like 70 different things to discuss or work on, but of course most of those things will never actually become reality.

With so much possible or potential work ahead, we need to involve more people that want to and can consider writing specs and to show how easy it apparently can be, Martin demoed how to write a first I-D draft using the fancy Internet Draft Template Repository. Go check it out!

Poul-Henning Kamp brought up the topic of “CO2 usage of the Internet” and argued for that current and future protocol work need to consider the environmental impact and how “green” protocols are. Ilya Grigorik (Google) showed off numbers from http archive.org‘s data and demoed how easy it is to use the big query feature to extract useful information and statistical info out of the vast amount of data they’ve gathered there. Brad Fitspatrick (Google) showed off his awesome tool h2i and how we can use it to poke on and test HTTP/2 server implementations in a really convenient and almost telnet-style command line using way.

Finally, Mark Nottingham (Akamai) showed off his redbot.org service that runs HTTP against a site, checks its responses and reports with details exactly what it responds and why and provide a bunch of analysis and informational based on that.

Such an eventful day really had to be rounded off with a bunch of beers and so we did. The HTTP Workshop of the summer 2015 ended. The event was great. The attendees were great. The facilities and the food were perfect. I couldn’t ask for more. Thanks for arranging such a great happening!

I’ll round off showing off my laptop lid after the two new stickers of the week were applied. (The HTTP Workshop one and an Apache one I got from Roy):

laptop-stickers

… I’ll get up early tomorrow morning and fly back home.

Mozilla, Network, Technology, Web

A third day of HTTP Workshopping

I’ve met a bunch of new faces and friends here at the HTTP Workshop in Münster. Several who I’ve only seen or chatted with online before and some that I never interacted with until now. Pretty awesome really.

Out of the almost forty HTTP fanatics present at this workshop, five persons are from Google, four from Mozilla (including myself) and Akamai has three employees here. Those are the top-3 companies. There are a few others with 2 representatives but most people here are the only guys from their company. Yes they are all guys. We are all guys. The male dominance at this event is really extreme and we’ve discussed this sad circumstance during breaks and it hasn’t gone unnoticed.

This particular day started out grand with Eric Rescorla (of Mozilla) talking about HTTP Security in his marvelous high-speed style. Lots of talk about how how the HTTPS usage is right now on  the web, HTTPS trends, TLS 1.3 details and when it is coming and we got into a lot of talk about how HTTP deprecation and what can and cannot be done etc.

Next up was a presentation about HTTP Privacy and Anonymity by Mike Perry (from the Tor project) about lots of aspects of what the Tor guys consider regarding fingerprinting, correlation, network side-channels and similar things that can be used to attempt to track user or usage over the Tor network. We got into details about what recent protocols like HTTP/2 and QUIC “leak” or open up for fingerprinting and what (if anything) can or could be done to mitigate the effects.

Evolving HTTP Header Fields by Julian Reschke (of Green Bytes) then followed, discussing all the variations of header syntax that we have in HTTP and how it really is not possible to write a generic parser that can handle them, with a suggestion on how to unify this and introduce a common format for future new headers. Julian’s suggestion to use JSON for this ignited a discussion about header formats in general and what should or could be done for HTTP/3 and if keeping support for the old formats is necessary or not going forward. No real consensus was reached.

Willy Tarreau (from HAProxy) then took us into the world of HTTP Infrastructure scaling and Load balancing, and showed us on the microsecond level how fast a load balancer can be, how much extra work adding HTTPS can mean and then ending with a couple suggestions of what he thinks could’ve helped his scenario. That then turned into a general discussion and network architecture brainstorm on what can be done, how it could be improved and what TLS and other protocols could possibly be do to aid. Cramming out every possible gigabit out of load balancers certainly is a challange.

Talking about cramming bits, Kazuho Oku got to show the final slides when he showed how he’s managed to get his picohttpparser to parse HTTP/1 headers at a speed that is only slightly slower than strlen() – including a raw dump of the x86 assembler the code is turned into by a compiler. What could possibly be a better way to end a day full of protocol geekery?

Google graciously sponsored the team dinner in the evening at a Peruvian place in the town! Yet another fully packed day has ended.

I’ll top off today’s summary with a picture of the gift Mark Nottingham (who’s herding us through these days) was handing out today to make us stay keen and alert (Mark pointed out to me that this was a gift from one of our Japanese friends here):

kitkat

Mozilla, Network

HTTP Workshop, second day

All 37 of us gathered again on the 3rd floor in the Factory hotel here in Münster. Day two of the HTTP Workshop.

Jana Iyengar (from Google) kicked off this morning with his presentations on HTTP and the Transport Layer and QUIC. Very interesting area if you ask me – if you’re interested in this, you really should check out the video recording from the barbof they did on this topic in the recent Prague IETF. It is clear that a team with dedication, a clear use-case, a fearless approach to not necessarily maintaining “layers” and a handy control of widely used servers and clients can do funky experiments with new transport protocols.

I think there was general agreement with Jana’s statement that “Engagement with the transport community is critical” for us to really be able to bring better web protocols now and in the future. Jana’s excellent presentations were interrupted a countless number of times with questions, elaborations, concerns and sub-topics from attendees.

Gaetano Carlucci followed up with a presentation of their QUIC evaluations, showing how it performs under various situations like packet loss etc in comparison to HTTP/2. Lots of transport related discussions followed.

We rounded off the afternoon with a walk through the city (the rain stopped just minutes before we took off) to the town center where we tried some of the local beers while arguing their individual qualities. We then took off in separate directions and had dinner in smaller groups across the city.

snackstation

Mozilla, Network, Web

The HTTP Workshop started

So we started today. I won’t get into any live details or quotes from the day since it has all been informal and we’ve all agreed to not expose snippets from here without checking properly first. There will be a detailed report put together from this event afterwards.

The most critical peace of information is however how we must not walk on the red parts of the sidewalks here in Münster, as that’s the bicycle lane and they (the bicyclers) can be ruthless there.

We’ve had a bunch of presentations today with associated Q&A and follow-up discussions. Roy Fielding (HTTP spec pioneer) started out the series with a look at HTTP full of historic details and views from the past and where we are and what we’ve gone through over the years. Patrick Mcmanus (of Firefox HTTP networking) took us through some of the quirks of what a modern day browser has to do to speak HTTP and topped it off with a quiz regrading Firefox metrics. Did you know 31% of all Firefox HTTP requests get fulfilled by the cache or that 73% of all Firefox HTTP/2 connections are used more than once but only 7% of the HTTP/1 ones?

Poul-Henning Kamp (author of Varnish) brought his view on HTTP/2 from an intermediary’s point of view with a slightly pessimistic view, not totally unlike what he’s published before. Stefan Eissing (from Green Bytes) entertained us by talking about his work on writing mod_h2 for Apache Httpd (and how it might be included in the coming 2.4.x release) and we got to discuss a bit around timing measurements and its difficulties.

We rounded off the afternoon with a priority and dependency tree discussion topped off with a walk-through of numbers and slides from Kazuho Oku (author of H2O) on how dependency-trees really help and from Moto Ishizawa (from Yahoo! Japan) explaining Firefox’s (Patrick’s really) implementation of dependencies for HTTP/2.

We spent the evening having a 5-course (!) meal at a nice Italian restaurant while trading war stories about HTTP, networking and the web. Now it is close to midnight and it is time to reload and get ready for another busy day tomorrow.

I’ll round off with a picture of where most of the important conversations were had today:

kafeestation