One positive thing among many others at this version of the HTTP Workshop (day one, day two) is the fact that there have been several new faces showing up here. People who have not previously attended any HTTP Workshops. Getting fresh blood into the mix is great. A chance to maybe lower the average age of the attendees also feels welcome.

This half day was the final session for this time. Three topics were dealt with.

Do you speak HTTP? Getting your HTTP implementation to do right according to the specification can be a challenge. There is a whole range of existing tests for various areas of HTTP but there might still be a place to add HTTP semantic tests in particular for servers. Discussions brought about reflections around testing, doing tests, test formats, other tests, test infrastructure and more. I think the general sense was that yes it would be great. At least if someone else makes it happen…

Every HTTP stack is an intermediary – HTTP semantics is the (requirement for low-level) API. Yes. Lots of nodding around the huge table.

Workshop feedback and thoughts. What is a good cadence for future events, how long should the events be etc. This is probably the maximum amount of attendees we can handle using the same setup. This event was clearly better than several of the past ones in terms of diversity, but I will second our “workshop maestro” in that it could improve further still. We also discussed whether do-arranging together with IETF is good or bad, should it then be before or after IETF?

I think the consensus said that making it biannual event is good. The reasoning for keeping the event in Europe has been because a larger share of the European attendees come from smaller companies compared to the non-Europeans which to a larger degree come from larger companies that might have it easier to pay for longer trips.

My personal take

The HTTP Workshop is a one-of-a-kind event. At these events everything is about and around HTTP with an information density level that is super high. We get to learn how things actually work for people or that do not work. And that we are not alone in whatever struggles or HTTP challenges we have.

Networking with other doers here and absorbing every protocol detail being expressed, gives food for thoughts and lessons to take advantage from in years to come when we for sure are going to take HTTP transfers further. This is in many ways a kind of brain fertilizer event.

Did I mention I enjoyed it? I will certainly try to attend the next one.

The fun continues. See day one.

In an office building close to the Waterloo station in London, around 40 persons again sat down at this giant table forming a big square that made it possible for us all to see each other. One by one there were brief presentations done with follow-up discussions. The discussions often reiterated old truths, brought up related topics and sometimes went deep down into the weeds about teeny weeny details of the involved protocol specs. The way we love it.

The people around the table represent Ericsson, Google, Microsoft, Apple, Meta, Akamai, Cloudflare, Fastly, Mozilla, Varnish. Caddy, Nginx, Haproxy, Tomcat, Adobe and curl and probably a few more I forget now. One could say with some level of certainty that a large portion of every day HTTP traffic in the world is managed by things managed by people present here.

This morning we all actually understood that the south entrance is actually the east one (yeah, that’s a so called internal joke) and most of us were sitting down, eager and prepared when the day started at 9:30 am.

Capsule. The capsule protocol (RFC 9297) is a way to, put simply, send UDP packets/datagrams over old style HTTP/1 or HTTP/2 proxies.

Cookies. With the 6265bis effort well on its way to ship as an updated RFC, there is an effort and intent to take yet another stab at improving and refreshing the cookie spec situation. In particular to better split off browser management and API related stuff from the more network-oriented over-the-wire details. You know yours truly never ceases an opportunity to voice his opinion on cookies… I approve of this attempt as well, as I think increasing clarity and improving the specification situation can’t but to help improve things.

Declarative web push. There’s an ongoing effort to improve web push – not to be confused with server push, so that it can be done easier and without needing JavaScript to manage it in the client side.

Reverse HTTP. There are origins who want to contact their CDNs without having to listening on any ports/sockets and still be able to provide content. That’s one of the use cases for Reverse HTTP and we got to learn details from internet drafts done on the topics for the last fifteen years and why it might still be a worthwhile effort and why the use cases still exist. But is there an enough demand to put it into HTTP?

Server Stack Detection. A discussion around how someone can detect the origin of the server stack of any given HTTP server implementation. Should there be a better way? What is the downside of introducing what would basically be the server version of the user-agent header field? Lots of productive discussions on how to avoid recreating problems of the past but in a reversed way.

MoQ: What is it and why is it not just HTTP/3? Was an educational session about the ongoing work done in this working group that is wrongly named and would appreciate more input from the general protocol community.

New HTTP stack. A description of the journey of a full HTTP stack rewrite: how components can be chained together and in which order and a follow-up discussion about if this should be included in documentation and if so in which way etc. Lessons included that the spec is one thing, the Internet is another. Maybe not an entirely new revelation.

Multiplexing in the year 2024. There are details in HTTP/2 multiplexing that does not really work, there are assumptions that are now hard to change. To introduce new protocols and features in the modern HTTP stack, things need to be done for both HTTP/2 and HTTP/3 that are similar but still different and it forces additional work and pain.

What if we create a way to do multiplexing over TCP, so called “over streams”, so that the HTTP/3 fallback over TCP could still be done using HTTP/3 framing. This would allow future new protocols to remain HTTP/3-only and just make the transport be either QUIC+UDP or Streams-over TCP+TLS. This triggered a lot of discussions, mostly positive and forward-looking but also a lot of concerns raised about additional work and yet another protocols component to write and implement that then needs to be supported until the end of times because things never truly go away completely.

I think this sounds like a fun challenge! Count me in.

End of day two. I need a beer or two to digest this.

Day one.

For the sixth time, this informal group of HTTP implementers and related “interested parties” unite in a room over a couple of days doing a HTTP Workshop. Nine years since that first event in Münster, Germany.

If you are someone like me, obsessed with networking and HTTP in particular this is certainly the place to be. Talking and discussing past lessons, coming changes and protocol dreams in several days with like-minded people is a blast. The people on these events are friends that I don’t always get to hang out with too often. Many of the attendees here have been involved in this community for a long time and have attended all or most of the past workshops as well. I have fortunately been able to attend all of them so far.

This time we are in London.

Let me tell you a little about the topics of day one – without spilling the beans about exactly who said what or what the company they came from. (I will add links to the presentations later once I know where to link to.)

Make Cleartext HTTP harder. The first discussion point of the day. While we have made HTTPS easier over recent years it can only take us so far. What if we considered means to make HTTP harder to use as the next level efforts to further reduce its use over the internet. The HSTS preload list is only growing. Should we instead convert it into a HSTS exclude list that can shrink over time? This triggered a looong a discussion in the group which brought back a lot of old arguments and reasoning from days I thought we had left behind long ago.

HTTP 2/3 abuses. A prominent implementer of a HTTP proxy/load balancer walked us through a whole series of different HTTP/2 and HTTP/3 protocols details that attackers can have been exploiting in recent years, with details about what can be done to mitigate such attacks. It made several other implementers mention how they take similar precautions and some other general discussions around the topics of what can be considered normal use of the protocol and what is not.

Idle connections & mobile: beneficial or harmful. 0-RTT instead of idle connections. There is a non-negligible cost associate with keeping connections alive for clients running on mobile phones. Would it be possible to instead move forward into a world when they are not kept alive but instead closed and 0-RTT opened again next time they are needed? Again the room woke up to a long discussion about the benefits and problems with doing this – which if it would be possible probably would save a lot of battery time on the average mobile phones.

QUIC pacing. We learned that it is very important for servers to implement decent QUIC pacing as it can increase performance up to 20 times compared to no pacing at all. What about using the flow control properly? What about changing the default buffer sizes for UDP sockets in the Linux kernel to something similar to TCP sockets in order to help the default case to perform better?

HTTP prioritization for product performance. The HTTP/2 way of doing prioritization was deemed a failure and too complicated a long time ago but in this presentation we were taught that there are definitely use cases and scenarios where the regular HTTP/3 priority setup is helpful and improves performs. Examples and descriptions for a popular and well used client were shown.

Allowing HTTP clients to use stale DNS data. What if HTTP clients would use stale data instead of having to wait for the DNS resolver response as a means to avoid having to wait a whole RTT to get the date that in a fair amount of the cases is the same as the stale data. Again a long discussion around TTLs for DNS queries and the fact that some clients are already doing this, in more or less explicit ways.

QUIC cache DSR. As the last talk of the the afternoon we got in the details of Direct Server Response for QUIC and how this can improve performance and problems and challenges involved with this. It then indirectly took us into a long sub-thread talking about HTTP caching, Vary headers and what could and should be done to improve things going forward. There seems to be an understanding that it would be good to improve the current situation but it is not entirely clear to this author exactly what that would entail.

When we then took a walk through the streets of London, only to have an awesome dinner during which we could all conclude that HTTP still is not ready. There is still work to be done. There are challenges left to overcome.

See you tomorrow for day two.