Category Archives: Mozilla

Talked HTTP/2 at ApacheCon

I was invited as one of the speakers at the ApacheCon core conference in Budapest, Hungary on October 1-2, 2015.


I was once again spreading the news about HTTP/2, why it was made and how it works and of course: updated numbers on adoption right now.

The talk was unfortunately not filmed, but I’ve put my slides for this version of my talk online. Readers of this blog and those who’ve seen my presentations before will recognize large parts of it.

Following my talk was talks about mod_http2, the Apache module for HTTP/2 that will be coming in the upcoming 2.4.17 release of Apache Httpd, explained by its author Stefan Eissing. The name of the module was actually a bit of a surprise to me since it has been known as just mod_h2 for its entire life time up until now.

William A Rowe took us through the state of TLS for the main Apache servers and yeah, the state seem to be pretty good and they’re coming along really well. TLS and then HTTPS is important as that’s really a prerequisite for HTTP/2

I also got to listen to Mark Thomas explain the agonies of making Tomcat support HTTP/2, and then perhaps especially how ALPN and a good set of ciphers are hard to get in Java.

Jean-Frederic Clere then explained how to activate HTTP/2 on all the Apache servers (tomcat, httpd and traffic server) and a little about their HTTP/2 state, following with an explanation how they worked on tomcat to make that use OpenSSL for the TLS layer (including ALPN) to avoid the deadlock of decent TLS support in Java.

All in all, a great track and splendid talks with deep technical content. Exactly the way I like it. Thanks everyone. Apachecon certainly delivered for me! Twas fun.

daniel weekly 42, switching off Nagle


See you at ApacheCon on Friday!


14% HTTP/2 thanks to nginx ?

Brotli everywhere! Firefox, libbrotli

The –libcurl flaw is fixed (and it was GONE from github for a few hours)

http2 explained in Swedish

No, the cheat sheet cannot be in the man page. But…

bug of the week: the http/2 performance fix


option of the week: -k

Talking at the GOTO Conference next week

Yours truly on “kodsnack”

kodsnackKodsnack is a Swedish-speaking weekly podcast with a small team of web/app- developers discussing their experiences and thoughts on and around software development.

I was invited to participate a week ago or so, and I had a great time. Not surprisingly, the topics at hand moved a lot around curl, Firefox and HTTP/2. The recorded episode has now gone live, today.

You can find kodsnack episode 120 here, and again, it is all Swedish.

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‘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 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):


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

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):


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.


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:


HTTP Workshop 2015, day -1

http workshopI’ve traveled to a rainy and gray Münster, Germany, today and checked in to my hotel for the coming week and the HTTP Workshop. Tomorrow is the first day and I’m looking forward to it probably a little too much.

There is a whole bunch of attendees coming. Simply put, most of the world’s best brains and the most eager implementers of the HTTP stacks that are in use today and will be in use tomorrow (with a bunch of notable absentees of course but you know you’ll be missed). I’m happy and thrilled to be able to take part during this coming week.

daniel weekly

daniel weekly screenshot

My series of weekly videos, in lack of a better name called daniel weekly, reached episode 35 today. I’m celebrating this fact by also adding an RSS-feed for those of you who prefer to listen to me in an audio-only version.

As an avid podcast listener myself, I can certainly see how this will be a better fit to some. Most of these videos are just me talking anyway so losing the visual shouldn’t be much of a problem.

A typical episode

I talk about what I work on in my open source projects, which means a lot of curl stuff and occasional stuff from my work on Firefox for Mozilla. I also tend to mention events I attend and HTTP/networking developments I find interesting and grab my attention. Lots of HTTP/2 talk for example. I only ever express my own personal opinions.

It is generally an extremely geeky and technical video series.

Every week I mention a (curl) “bug of the week” that allows me to joke or rant about the bug in question or just mention what it is about. In episode 31 I started my “command line options of the week” series in which I explain one or a few curl command line options with some amount of detail. There are over 170 options so the series is bound to continue for a while. I’ve explained ten options so far.

I’ve set a limit for myself and I make an effort to keep the episodes shorter than 20 minutes. I’ve not succeed every time.


The 35 episodes have been viewed over 17,000 times in total. Episode two is the most watched individual one with almost 1,500 views.

Right now, my channel has 190 subscribers.

The top-3 countries that watch my videos: USA, Sweden and UK.

Share of viewers that are female: 3.7%

RFC 7540 is HTTP/2

HTTP/2 is the new protocol for the web, as I trust everyone reading my blog are fully aware of by now. (If you’re not, read http2 explained.)

Today RFC 7540 was published, the final outcome of the years of work put into this by the tireless heroes in the HTTPbis working group of the IETF. Closely related to the main RFC is the one detailing HPACK, which is the header compression algorithm used by HTTP/2 and that is now known as RFC 7541.

The IETF part of this journey started pretty much with Mike Belshe’s posting of draft-mbelshe-httpbis-spdy-00 in February 2012. Google’s SPDY effort had been going on for a while and when it was taken to the httpbis working group in IETF, where a few different proposals on how to kick off the HTTP/2 work were debated.

HTTP team working in LondonThe first “httpbis’ified” version of that document (draft-ietf-httpbis-http2-00) was then published on November 28 2012 and the standardization work began for real. HTTP/2 was of course discussed a lot on the mailing list since the start, on the IETF meetings but also in interim meetings around the world.

In Zurich, in January 2014 there was one that I only attended remotely. We had the design team meeting in London immediately after IETF89 (March 2014) in the Mozilla offices just next to Piccadilly Circus (where I took the photos that are shown in this posting). We had our final in-person meetup with the HTTP team at Google’s offices in NYC in June 2014 where we ironed out most of the remaining issues.

In between those two last meetings I published my first version of http2 explained. My attempt at a lengthy and very detailed description of HTTP/2, including describing problems with HTTP/1.1 and motivations for HTTP/2. I’ve since published eleven updates.

HTTP team in London, debating protocol detailsThe last draft update of HTTP/2 that contained actual changes of the binary format was draft-14, published in July 2014. After that, the updates were in the language and clarifications on what to do when. There are some functional changes (added in -16 I believe) for like when which sort of frames are accepted that changes what a state machine should do, but it doesn’t change how the protocol looks on the wire.

RFC 7540 was published on May 15th, 2015

I’ve truly enjoyed having had the chance to be a part of this. There are a bunch of good people who made this happen and while I am most certainly forgetting key persons, some of the peeps that have truly stood out are: Mark, Julian, Roberto, Roy, Will, Tatsuhiro, Patrick, Martin, Mike, Nicolas, Mike, Jeff, Hasan, Herve and Willy.

http2 logo