Category Archives: Web

web stuff

HTTP Workshop s03e02

(Season three, episode two)

Previously, on the HTTP Workshop. Yesterday ended with a much appreciated group dinner and now we’re back energized and eager to continue blabbing about HTTP frames, headers and similar things.

Martin from Mozilla talked on “connection management is hard“. Parts of the discussion was around the HTTP/2 connection coalescing that I’ve blogged about before. The ORIGIN frame is a draft for a suggested way for servers to more clearly announce which origins it can answer for on that connection which should reduce the frequency of 421 needs. The ORIGIN frame overrides DNS and will allow coalescing even for origins that don’t otherwise resolve to the same IP addresses. The Alt-Svc header, a suggested CERTIFICATE frame and how does a HTTP/2 server know for which origins it can do PUSH for?

A lot of positive words were expressed about the ORIGIN frame. Wildcard support?

Willy from HA-proxy talked about his Memory and CPU efficient HPACK decoding algorithm. Personally, I think the award for the best slides of the day goes to Willy’s hand-drawn notes.

Lucas from BBC talked about usage data for iplayer and how much data and number of requests they serve and how their largest share of users are “non-browsers”. Lucas mentioned their work on writing a libcurl adaption to make gstreamer use it instead of libsoup. Lucas talk triggered a lengthy discussion on what needs there are and how (if at all) you can divide clients into browsers and non-browser.

Wenbo from Google spoke about Websockets and showed usage data from Chrome. The median websockets connection time is 20 seconds and 10% something are shorter than 0.5 seconds. At the 97% percentile they live over an hour. The connection success rates for Websockets are depressingly low when done in the clear while the situation is better when done over HTTPS. For some reason the success rate on Mac seems to be extra low, and Firefox telemetry seems to agree. Websockets over HTTP/2 (or not) is an old hot topic that brought us back to reiterate issues we’ve debated a lot before. This time we also got a lovely and long side track into web push and how that works.

Roy talked about Waka, a HTTP replacement protocol idea and concept that Roy’s been carrying around for a long time (he started this in 2001) and to which he is now coming back to do actual work on. A big part of the discussion was focused around the wakli compression ideas, what the idea is and how it could be done and evaluated. Also, Roy is not a fan of content negotiation and wants it done differently so he’s addressing that in Waka.

Vlad talked about his suggestion for how to do cross-stream compression in HTTP/2 to significantly enhance compression ratio when, for example, switching to many small resources over h2 compared to a single huge resource over h1. The security aspect of this feature is what catches most of people’s attention and the following discussion. How can we make sure this doesn’t leak sensitive information? What protocol mechanisms exist or can we invent to help out making this work in a way that is safer (by default)?

Trailers. This is again a favorite topic that we’ve discussed before that is resurfaced. There are people around the table who’d like to see support trailers and we discussed the same topic in the HTTP Workshop in 2016 as well. The corresponding issue on trailers filed in the fetch github repo shows a lot of the concerns.

Julian brought up the subject of “7230bis” – when and how do we start the work. What do we want from such a revision? Fixing the bugs seems like the primary focus. “10 years is too long until update”.

Kazuho talked about “HTTP/2 attack mitigation” and how to handle clients doing many parallel slow POST requests to a CDN and them having an origin server behind that runs a new separate process for each upload.

And with this, the day and the workshop 2017 was over. Thanks to Facebook for hosting us. Thanks to the members of the program committee for driving this event nicely! I had a great time. The topics, the discussions and the people – awesome!

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.

Post FOSDEM 2017

I attended FOSDEM again in 2017 and it was as intense, chaotic and wonderful as ever. I met old friends, got new friends and I got to test a whole range of Belgian beers. Oh, and there was also a set of great open source related talks to enjoy!

On Saturday at 2pm I delivered my talk on curl in the main track in the almost frighteningly large room Janson. I estimate that it was almost half full, which would mean upwards 700 people in the audience. The talk itself went well. I got audible responses from the audience several times and I kept well within my given time with time over for questions. The trickiest problem was the audio from the people who asked questions because it wasn’t at all very easy to hear, while the audio is great for the audience and in the video recording. Slightly annoying because as everyone else heard, it made me appear half deaf. Oh well. I got great questions both then and from people approaching me after the talk. The questions and the feedback I get from a talk is really one of the things that makes me appreciate talking the most.

The video of the talk is available, and the slides can also be viewed.

So after I had spent some time discussing curl things and handing out many stickers after my talk, I managed to land in the cafeteria for a while until it was time for me to once again go and perform.

We’re usually a team of friends that hang out during FOSDEM and we all went over to the Mozilla room to be there perhaps 20 minutes before my talk was scheduled and wow, there was a huge crowd outside of that room already waiting by the time we arrived. When the doors then finally opened (about 10 minutes before my talk started), I had to zigzag my way through to get in, and there was a large amount of people who didn’t get in. None of my friends from the cafeteria made it in!

The Mozilla devroom had 363 seats, not a single one was unoccupied and there was people standing along the sides and the back wall. So, an estimated nearly 400 persons in that room saw me speak about HTTP/2 deployments numbers right now, how HTTP/2 doesn’t really work well under 2% packet loss situations and then a bit about how QUIC can solve some of that and what QUIC is and when we might see the first experiments coming with IETF-QUIC – which really isn’t the same as Google-QUIC was.

To be honest, it is hard to deliver a talk in twenty minutes and I  was only 30 seconds over my time. I got questions and after the talk I spent a long time talking with people about HTTP, HTTP/2, QUIC, curl and the future of Internet protocols and transports. Very interesting.

The video of my talk can be seen, and the slides are online too.

I’m not sure if I was just unusually unlucky in my choices, or if there really was more people this year, but I experienced that “FULL” sign more than usual this year.

I fully intend to return again next year. Who knows, maybe I’ll figure out something to talk about then too. See you there?

One URL standard please

Following up on the problem with our current lack of a universal URL standard that I blogged about in May 2016: My URL isn’t your URL. I want a single, unified URL standard that we would all stand behind, support and adhere to.

What triggers me this time, is yet another issue. A friendly curl user sent me this URL:

http://user@example.com:80@daniel.haxx.se

… and pasting this URL into different tools and browsers show that there’s not a wide agreement on how this should work. Is the URL legal in the first place and if so, which host should a client contact?

  • curl treats the ‘@’-character as a separator between userinfo and host name so ‘example.com’ becomes the host name, the port number is 80 followed by rubbish that curl ignores. (wget2, the next-gen wget that’s in development works identically)
  • wget extracts the example.com host name but rejects the port number due to the rubbish after the zero.
  • Edge and Safari say the URL is invalid and don’t go anywhere
  • Firefox and Chrome allow ‘@’ as part of the userinfo, take the ’80’ as a password and the host name then becomes ‘daniel.haxx.se’

The only somewhat modern “spec” for URLs is the WHATWG URL specification. The other major, but now somewhat aged, URL spec is RFC 3986, made by the IETF and published in 2005.

In 2015, URL problem statement and directions was published as an Internet-draft by Masinter and Ruby and it brings up most of the current URL spec problems. Some of them are also discussed in Ruby’s WHATWG URL vs IETF URI post from 2014.

What I would like to see happen…

Which group? A group!

Friends I know in the WHATWG suggest that I should dig in there and help them improve their spec. That would be a good idea if fixing the WHATWG spec would be the ultimate goal. I don’t think it is enough.

The WHATWG is highly browser focused and my interactions with members of that group that I have had in the past, have shown that there is little sympathy there for non-browsers who want to deal with URLs and there is even less sympathy or interest for URL schemes that the popular browsers don’t even support or care about. URLs cover much more than HTTP(S).

I have the feeling that WHATWG people would not like this work to be done within the IETF and vice versa. Since I’d like buy-in from both camps, and any other camps that might have an interest in URLs, this would need to be handled somehow.

It would also be great to get other major URL “consumers” on board, like authors of popular URL parsing libraries, tools and components.

Such a URL group would of course have to agree on the goal and how to get there, but I’ll still provide some additional things I want to see.

Update: I want to emphasize that I do not consider the WHATWG’s job bad, wrong or lost. I think they’ve done a great job at unifying browsers’ treatment of URLs. I don’t mean to belittle that. I just know that this group is only a small subset of the people who probably should be involved in a unified URL standard.

A single fixed spec

I can’t see any compelling reasons why a URL specification couldn’t reach a stable state and get published as *the* URL standard. The “living standard” approach may be fine for certain things (and in particular browsers that update every six weeks), but URLs are supposed to be long-lived and inter-operate far into the future so they really really should not change. Therefore, I think the IETF documentation model could work well for this.

The WHATWG spec documents what browsers do, and browsers do what is documented. At least that’s the theory I’ve been told, and it causes a spinning and never-ending loop that goes against my wish.

Document the format

The WHATWG specification is written in a pseudo code style, describing how a parser would “walk” over the string with a state machine and all. I know some people like that, I find it utterly annoying and really hard to figure out what’s allowed or not. I much more prefer the regular RFC style of describing protocol syntax.

IDNA

Can we please just say that host names in URLs should be handled according to IDNA2008 (RFC 5895)? WHATWG URL doesn’t state any IDNA spec number at all.

Move out irrelevant sections

“Irrelevant” when it comes to documenting the URL format that is. The WHATWG details several things that are related to URL for browsers but are mostly irrelevant to other URL consumers or producers. Like section “5. application/x-www-form-urlencoded” and “6. API”.

They would be better placed in a “URL considerations for browsers” companion document.

Working doesn’t imply sensible

So browsers accept URLs written with thousands of forward slashes instead of two. That is not a good reason for the spec to say that a URL may legitimately contain a thousand slashes. I’m totally convinced there’s no critical content anywhere using such formatted URLs and no soul will be sad if we’d restricted the number to a single-digit. So we should. And yeah, then browsers should reject URLs using more.

The slashes are only an example. The browsers have used a “liberal in what you accept” policy for a lot of things since forever, but we must resist to use that as a basis when nailing down a standard.

The odds of this happening soon?

I know there are individuals interested in seeing the URL situation getting worked on. We’ve seen articles and internet-drafts posted on the issue several times the last few years. Any year now I think we will see some movement for real trying to fix this. I hope I will manage to participate and contribute a little from my end.

DMARC helped me ditch gmail

I’ve been a gmail user for many years (maybe ten). Especially since the introduction of smart phones it has been a really convenient system to read email on the go. I rarely respond to email from my phone but I’ve done that occasionally too and it has worked adequately.

All this time I’ve used my own domain and email address and simply forwarded a subset of my email over to gmail, and I had gmail setup so that when I emailed out from it, it would use my own email address and not the @gmail.com one. Nothing fancy, just convenient. The gmail spam filter is also pretty decent so it helped me to filter off some amount of garbage too.

It was fine until DMARC

However, with the rise of DMARC over the recent years and with Google insisting on getting on that bandwagon, it has turned out to be really hard to keep forwarding email to gmail (since gmail considers forwarded emails using such headers fraudulent and it rejects them). So a fair amount of email simply never showed up in my gmail inbox (and instead caused the senders to get a bounce from a gmail address they didn’t even know I had).

I finally gave up and decided gmail doesn’t work for this sort of basic email setup anymore. DMARC and its siblings have quite simply made it impossible to work with emails this way, a way that has been functional for decades (I used similar approaches already back in the mid 90s on my first few jobs).

Similarly, DMARC has turned out to be a pain for mailing lists since they too forward email in a similar fashion and this causes the DMARC police to go berserk. Luckily, recent versions of mailman has options that makes it rewrite the From:-lines from senders that send emails from domains that have strict DMARC policies. That mitigates most of the problems for mailman lists. I love the title of this old mail on the subject: “Yahoo breaks every mailing list in the world including the IETF’s

I’m sure DMARC works for the providers in the sence that they block huge amounts of spam and fake users and that’s what it was designed for. The fact that it also makes ordinary old-school mail forwards really difficult and forces mailing list admins all over to upgrade mailman or just keep getting rejects since they use mailing list software that lacks the proper features, that’s probably all totally ignored. DMARC was as designed: it reduces spam at the big providers’ systems. Mission accomplished. The fact that they at the same time made world wide Internet email a lot less useful is probably not something they care about.

It’s done

gmail can read mails from remote inboxes, but it doesn’t support IMAP (only POP3) so simply switching to such a method wouldn’t even work. I just refuse to enable POP3 anywhere again.

Of course it isn’t an irreversible decision, but I’ve stopped the forward to gmail, cleared the inbox there and instead I’ve switched to Aqua mail on Android. It seems fairly feature complete and snappy. It isn’t quite as fancy and cool as the gmail client, but hopefully it will do its job.

The biggest drawback I’ve felt after a couple of weeks is the gmail spam filter. I do run spamassassin on my server and it catches the large bulk of all spams, but having the gmail spam system on top of that was able to block more silliness from my phone than spamassassin does alone.

1,000,000 sites run HTTP/2

… out of the top ten million sites that is. So there’s at least that many, quite likely a few more.

This is according to w3techs who runs checks daily. Over the last few months, there have been about 50,000 new sites per month switching it on.

ht2-10-percent

It also shows that the HTTP/2 ratio has increased from a little over 1% deployment a year ago to the 10% today.

HTTP/2 gets more used the more  popular site it is. Among the top 1,000 sites on the web, more than 20% of them use HTTP/2. HTTP/2 also just recently (September 9) overcame SPDY among the top-1000 most popular sites.

h2-sep28

On September 7, Amazon announced their CloudFront service having enabled HTTP/2, which could explain an adoption boost over the last few days. New CloudFront users get it enabled by default but existing users actually need to go in and click a checkbox to make it happen.

As the web traffic of the world is severely skewed toward the top ones, we can be sure that a significantly larger share than 10% of the world’s HTTPS traffic is using version 2.

Recent usage stats in Firefox shows that HTTP/2 is used in half of all its HTTPS requests!

http2

HTTP/2 connection coalescing

Section 9.1.1 in RFC7540 explains how HTTP/2 clients can reuse connections. This is my lengthy way of explaining how this works in reality.

Many connections in HTTP/1

With HTTP/1.1, browsers are typically using 6 connections per origin (host name + port). They do this to overcome the problems in HTTP/1 and how it uses TCP – as each connection will do a fair amount of waiting. Plus each connection is slow at start and therefore limited to how much data you can get and send quickly, you multiply that data amount with each additional connection. This makes the browser get more data faster (than just using one connection).

6 connections

Add sharding

Web sites with many objects also regularly invent new host names to trigger browsers to use even more connections. A practice known as “sharding”. 6 connections for each name. So if you instead make your site use 4 host names you suddenly get 4 x 6 = 24 connections instead. Mostly all those host names resolve to the same IP address in the end anyway, or the same set of IP addresses. In reality, some sites use many more than just 4 host names.

24 connections

The sad reality is that a very large percentage of connections used for HTTP/1.1 are only ever used for a single HTTP request, and a very large share of the connections made for HTTP/1 are so short-lived they actually never leave the slow start period before they’re killed off again. Not really ideal.

One connection in HTTP/2

With the introduction of HTTP/2, the HTTP clients of the world are going toward using a single TCP connection for each origin. The idea being that one connection is better in packet loss scenarios, it makes priorities/dependencies work and reusing that single connections for many more requests will be a net gain. And as you remember, HTTP/2 allows many logical streams in parallel over that single connection so the single connection doesn’t limit what the browsers can ask for.

Unsharding

The sites that created all those additional host names to make the HTTP/1 browsers use many connections now work against the HTTP/2 browsers’ desire to decrease the number of connections to a single one. Sites don’t want to switch back to using a single host name because that would be a significant architectural change and there are still a fair number of HTTP/1-only browsers still in use.

Enter “connection coalescing”, or “unsharding” as we sometimes like to call it. You won’t find either term used in RFC7540, as it merely describes this concept in terms of connection reuse.

Connection coalescing means that the browser tries to determine which of the remote hosts that it can reach over the same TCP connection. The different browsers have slightly different heuristics here and some don’t do it at all, but let me try to explain how they work – as far as I know and at this point in time.

Coalescing by example

Let’s say that this cool imaginary site “example.com” has two name entries in DNS: A.example.com and B.example.com. When resolving those names over DNS, the client gets a list of IP address back for each name. A list that very well may contain a mix of IPv4 and IPv6 addresses. One list for each name.

You must also remember that HTTP/2 is also only ever used over HTTPS by browsers, so for each origin speaking HTTP/2 there’s also a corresponding server certificate with a list of names or a wildcard pattern for which that server is authorized to respond for.

In our example we start out by connecting the browser to A. Let’s say resolving A returns the IPs 192.168.0.1 and 192.168.0.2 from DNS, so the browser goes on and connects to the first of those addresses, the one ending with “1”. The browser gets the server cert back in the TLS handshake and as a result of that, it also gets a list of host names the server can deal with: A.example.com and B.example.com. (it could also be a wildcard like “*.example.com”)

If the browser then wants to connect to B, it’ll resolve that host name too to a list of IPs. Let’s say 192.168.0.2 and 192.168.0.3 here.

Host A: 192.168.0.1 and 192.168.0.2
Host B: 192.168.0.2 and 192.168.0.3

Now hold it. Here it comes.

The Firefox way

Host A has two addresses, host B has two addresses. The lists of addresses are not the same, but there is an overlap – both lists contain 192.168.0.2. And the host A has already stated that it is authoritative for B as well. In this situation, Firefox will not make a second connect to host B. It will reuse the connection to host A and ask for host B’s content over that single shared connection. This is the most aggressive coalescing method in use.

one connection

The Chrome way

Chrome features a slightly less aggressive coalescing. In the example above, when the browser has connected to 192.168.0.1 for the first host name, Chrome will require that the IPs for host B contains that specific IP for it to reuse that connection.  If the returned IPs for host B really are 192.168.0.2 and 192.168.0.3, it clearly doesn’t contain 192.168.0.1 and so Chrome will create a new connection to host B.

Chrome will reuse the connection to host A if resolving host B returns a list that contains the specific IP of the connection host A is already using.

The Edge and Safari ways

They don’t do coalescing at all, so each host name will get its own single connection. Better than the 6 connections from HTTP/1 but for very sharded sites that means a lot of connections even in the HTTP/2 case.

curl also doesn’t coalesce anything (yet).

Surprises and a way to mitigate them

Given some comments in the Firefox bugzilla, the aggressive coalescing sometimes causes some surprises. Especially when you have for example one IPv6-only host A and a second host B with both IPv4 and IPv4 addresses. Asking for data on host A can then still use IPv4 when it reuses a connection to B (assuming that host A covers host B in its cert).

In the rare case where a server gets a resource request for an authority (or scheme) it can’t serve, there’s a dedicated error code 421 in HTTP/2 that it can respond with and the browser can then  go back and retry that request on another connection.

Starts out with 6 anyway

Before the browser knows that the server speaks HTTP/2, it may fire up 6 connection attempts so that it is prepared to get the remote site at full speed. Once it figures out that it doesn’t need all those connections, it will kill off the unnecessary unused ones and over time trickle down to one. Of course, on subsequent connections to the same origin the client may have the version information cached so that it doesn’t have to start off presuming HTTP/1.

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!

Workshop day two

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.

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!