Internet: Remote Work, Daniel Stenberg on Curl and QUIC/HTTP/3
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Our Essential List of Free Software for Remote Work
Team chat has already become an essential tool for teams looking to be more collaborative and less reliant on email. At Purism we use Matrix for team chat, 1 to 1 calls, video conferencing via Jitsi (open source video conferencing), adhoc file sharing and all our community chat channels. Matrix is a distributed (federated) network, similar to email, which means you can communicate across Matrix servers and compatible services.
You can self host Matrix or use a public instance like our own free Librem Chat service part of Librem One. All the goodness of Matrix conveniently hosted for you and accessible with one account that also gives you access to Librem Social, our hosted Mastodon instance, and our premium services: end-to-end encrypted email and VPN.
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Most office-based teams already have email and things like a company newsletter but we thought we’d share how we manage ours. Our company email and Librem Mail are powered by Dovecot and we use GNU Mailman for our newsletter and mailing lists.
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Daniel Stenberg: A curl dashboard
When I wrote up my looong blog post for the curl’s 22nd anniversary, I vacuumed my home directories for all the leftover scripts and partial hacks I’d used in the past to produce graphs over all sorts of things in the curl project. Being slightly obsessed with graphs, that means I got a whole bunch of them.
I made graphs with libreoffice
I dusted them off and made sure they all created a decent CSV output that I could use. I imported that data into libreoffice’s calc spreadsheet program and created the graphs that way. That was fun and I was happy with the results – and I could also manually annotate them with additional info. I then created a new git repository for the purpose of hosting the statistics scripts and related tools and pushed my scripts to it. Well, at least all the ones that seemed to work and were the most fun.
Having done the hard work once, it felt a little sad to just have that single moment snapshot of the project at the exact time I created the graphs, just before curl’s twenty-second birthday. Surely it would be cooler to have them updated automatically?
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A QUIC look at HTTP/3
Each HTTP session requires a TCP connection which, in turn, requires a three-way handshake to set up. Once that is done, "we can send data in a reliable data stream", Stenberg explained. TCP transmits data in the clear, so everyone can read what is transferred; the same thus holds true for the non-encrypted HTTP protocol. However, 80% of requests today are using the encrypted version, called Hypertext Transfer Protocol Secure (HTTPS), according to statistics of Mozilla (Firefox users) and Google (Chrome users). "The web is getting more and more encrypted", Stenberg explained. HTTPS uses Transport Layer Security (TLS); it adds security on the top of the stack of protocols, which are (in order): IP, TCP, TLS, and HTTP. The cost of TLS is another handshake that increases the latency. In return, we get privacy, security, and "you know you're talking to the right server".
HTTP/1 required clients to establish one new TCP connection per object, meaning that for each request, the browser needed to create a connection, send the request, read the response, then close it. "TCP is very inefficient in the beginning", Stenberg explained; connections transmit data slowly just after being established, then increase the speed until they discover what the link can support. With only one object to fetch before closing the connection, TCP was never getting up to speed. In addition, a typical web page includes many elements, including JavaScript files, images, stylesheets, and so on. Fetching one object at a time is slow, so browser developers responded by creating multiple connections in parallel.
That created too many connections to be handled by the servers, so typically the number of connections for each client was limited. The browser had to choose which of its few allowed connections to use for the next object; that led to the so-called "head-of-line blocking" problem. Think of a supermarket checkout line; you might choose the one that looks shortest, only to be stuck behind a customer with some sort of complicated problem. A big TCP efficiency improvement was added for HTTP/1.1 in 1997: open TCP connections can be reused for other requests. That improved the slow-start problem, but not the head-of-line blocking issue, which can be made even worse.
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