Node.js Node + JS Interactive 2019, 19 Dec 2019

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From YouTube: A QUIC Update - Trivikram Kamat

Description

A QUIC Update - Trivikram Kamat

The QUIC and HTTP/3 protocols are currently being developed by the IETF. While they are busy working, we've been busy working on an implementation within Node.js core. This presentation will introduce the protocol and the implementation and update on where things are at!

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Welcome to node.js interactive. This is a talk on STP. Three quick update. Remember that this is experimental, so do not try it in production. If you try it in production, do not blame me. My name is Sriram Kamath I'm, so Fidelma engineer my twitter handle is three week RAM and data handle is three week AR.

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If you see I did not get three week ram handle on github. That is because somebody I joined a tablet in 2015, and somebody else has taken it already. So if you become parents recently get get up handle for your kids, because that's more important than other social media, so.

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For node.js in directive is hashtag, not this interactive. If you're active on social media, you can also use HTTP, 3 or quick. If you like this talk, if you did like this talk, then use my name and what's my name again, most of you will have forgotten so I'll give like clue. Ok, so we are in Canada and it is very cold and you will be knowing this drink. It's called rum. It gives a lot of warmth. So imagine a weak rum, not a strong rum, a weak rum and add 3 in front of it.

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That's my name! So what's my history with not just I've been using node.js for 4 years now, I started contributing to node.js code in October. 2017 helped make a trip to stable, write, wrote unit test and fix some bugs. You can do the same with STP three will cover that. I became node.js code collaborator in March, 2018 and I organized a mentor for code n, LAN events. What are we going to cover in this talk? We are going to cover what is STB, 1.1 and y acp to was required.

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Then we will cover what is HCP to and wiht p3 was required.

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Then you will cover what is HDPE 3 and when is it coming? It's still, Draft is still accelerator. When is the coming, and we will see some sample code on the way.

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So I would like to thank James Snell, who is here he's not just a technical sharing company member and heading the work on implementing quick thanks, James and I. Like also like to thank the sponsors for his work, it is protocol labs and near forum I'll also like to thank Anna Henningsen. As James says, she fixes the books, which he introduces and I also thank Daniel, one young and many others who have contributed too quick already. I, also like to think that's. You know that's what your son for his awesome work in NGTC.

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We do like. We are using a new TCP to in for implementing quick, and he has done some amazing work. So, let's start with STP 0.9, which was published in 1991 and.

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It was very simple.

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It was just one line: protocol, okay, you get my page or HTML. You send get my page Waterman and you get my beta rest. Raymond awesome right, like life was so simple back in 1991, but things had to get complicated, so I step, II wondered Oh dot introduced in May 1996 and it will extensibility. Let us see what it did. Ok, this have you send request. This is what the response you get so now you can send version information, because now there is more than one HTTP protocol.

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You also send browser information because there are multiple browsers and then you send status code because not all requests are successful. Sometimes the redirect backs sometimes client error. Sometimes your server error. Then there are headers who did information? What kind of server is there? Ok, what kind of content type so, instead of sending content text, you can even send JSON and other types, and then we could. We could include multiple resources in the HTML file, so in this HTML file, that is an image being used.

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So then, STP 1.1, the standardized but came in June, 1999 and I- will not go through the headers, because there are too many headers. We will just see what were the improvements needs to be 1.1.

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So first improvement was precision, persistent connection in which you can use single TCP connection to send and receive multiple requests and responses which are serial, not the concurrent ones which are serial, and there was pipelining in which second request can be sent before the first one is fully transmitted and there was chum transfer encoding and there was additional cache control mechanism. There is content negotiation. We will see what were the issues with HTTP 1.1.

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So first issue is three round-trips per request, so this client in a server- and this is from blog post from cloud fair. They written a very good description, so client sends a tcp syn packet.

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Then server sends tcp, syn, plus AC kick line, sends tcp ack, then client says th, TLS, client, hello, service, ace, TLS, server,.

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Is not send okay, then HTP request is sent and CP response comes. Who has time for this? Okay, three round-trips per a TCP connection. Let's revisit this header issue. Number two was multiple PCP plus TLS connections. Ark were created for concurrent requests.

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So how does happen like you write applications right in in those applications you will be importing images will be importing CSS, you will be importing GS and these things have to be imported concurrently, and when that happens, multiple TCP connections are created and for each TCP connection there are three round-trips as we saw, so it takes a lot of time.

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So let us understand this by going through the code, because talking is boring. So let us see the code if you attended matias talk on streams you mentioned today that do not use pipe because it uses memory leaks anyway, you use some framework yeah, but here we are just writing normal, create a strictly typical, eight server. So if a request URL is, has just written index, if it is style, dot CSS hit return that okay, that's it so I'll just made it simpler.

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So if request URL is the home page, written index or HTML, and otherwise just a regular expression which reads: what's the file name is and return that file name from the files folder. Okay, let us go through the code because it is important. We will see how it works in STP, one and two and three so index.html. You input style at the top okay, then you import an image in the body.

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Then you say hello one because in the first program you have to say hello world and then we import a script and so go one by one. What each files to the side or CSS is just CSS, like just body, displays Flex forever. Here just say six. What.

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That it finds the name and change it. It changes it to know just interactive because we had no just interactive. So it's a hello note, yes interactive and it will change the image and upload a page to notice inductive image cool, that's after a second yeah after one cycle wait for second- and this is just a globe image- so let's see how it looks.

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So here you can see that we are requesting localhost first and then three concurrent requests are sent for CSS, J's and image, and then the JavaScript is executed after second the set timeout and then the image is sent and node.js interactive image is shown.

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Let us see how many tcp ports are created is very.

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So below I have a command telnet command, which looks for how many TCP connections are created. When you say that request is sent for localhost, only one TCP connections are created, it shows three records, but only one is created, but then, when it has to make three concurrent requests, you can see multiple TCP connections I created. That is the issue with STP 1.1.

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So what are the issues? A step? 201 one was three round-trips first request. Let me saw, and second one was multiple TCP potala TLS connections for concurrent requests. Now what did STP to do? It was published in May, 2015 and.

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You saw that three requests a send for three resources and steppy 1.1 in STP to only one PCP connection is created, although all three surfaced, so let us see how it works. So we write by step into server, so you create a server and then, if it is slash, you would get an index for xtml and otherwise you get the regular extra flex.

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So if you examine using the network tab, it will be same as HTTP 1.1. Only in the protocol column, you will see that H 2 is used. Okay, so you don't see that how many TCP connections are used so I go to the next slide and I watch for TCP connections using next read command and you will see that only one TCP connections are created, although three requests are sent simultaneously.

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So let us see the benefits of HTTP. We saw the one in benefit which is multiplexing and concurrency, so different HTTP requests are sent on to the same TCP connection, but there are some other benefits also like stream. Dependencies splines can indicate to server which dependents are important. There is H pack header compression where it reduces the length of the header field and codings by exploiting the redundancy, because headers have lot of redundant code, so it can be encoded and there is server push. A server can send.

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Resources with clients have not requested yet, but you will not go through that in detail. We will just see the issues it actually p2, because if there are no issues we ship into a ship III will not exist. So let's say the first issue: each pack is stateful, so the encoding and decoding tables. How do we maintain at the end point so because of which so what happens on each packet is sent first time it encodes something and when second packet is sent, it will use the encoded content.

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It will send a new content only if there are some changes. So that is one issue. Delta encoding is used in header compression, so this causes high resource consumption in Braille, tired. Then it's not easily routable along the network and the main issue which we'll discuss in today's talk is disappear, head of line blocking. So what is the CP head of line blocking when a single TCP packet is lost or corrupted? All subsequent packets are blocked until the last one can be successfully transmitted in HTTP 1.1.

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If this happens, you are blocking only one request, because there is only one request: HTTP request sent or a TCP connection, but in HTTP 2, since multiple requests and responses has carried over a single TCP connection, all those request responses will be blocked. So let us understand, understand this using uh-oh, so yeah. So before that we will see where this effect is most very severe is more significant. It is more significant on high latency networks, which are long distance.

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So if it is high, latency probability of packet getting lost is more or on mobile connections where probability of getting packet loss is more. So we will understand this using a chain metaphor. So this is a chain. Imagine these a TCP connection between two computers and what I am done is I, put green colors and red colors. Wear green color considered that CSS pocket and gallery jsj expected wear. Css and JS files are requested over the same pacific connection.

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If a J's packet is lost or corrupted, then the entire chain is broken, so the entire chain posts that J expected, which includes a circuits, have to be sent again. This is explained very well in HTTP, 3 explained if you want more details, so what does HTTP 3 over quick does so this is a draft 24 as of December 2019.

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So what it does is that when it is setting up multiple streams over quick connection, they are deterred independently, so that if any packet goes missing in one of the streams, only that stream has to pause and wait for the missing packet to get transmitted. So to understand this, let us see the chain analogy in which this CSS stream, this J's stream, if the J stream packet is lost, the CSS stream is not affected. Now we'll say: isn't this what HDPE one was doing? Are we going back?

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No because STP 3 is built on top of UDP.

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So on the left side you can see ICP 2, which is built on top of TCP next EP 3 is built on top of UDP and quick comes there in between speaking of UDP. I can tell you a joke, but most of you won't get it got it got it got it. You didn't get it. Let me still give it a try.

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Udp packet bar box in did you get it now, so click adds the volume to UDP. Ok, it adds error handling, it adds acknowledgment, it adds flow control, it adds packet sequencing built in and encryption TLS 1.3 and bi-directionally directional streams. So whatever benefits you have on TCP, those goodies will come to quick, amazing right and quick, also reduces round-trips. Remember we saw that three round-trips per request. Who has time for that so in UDP it will take on.

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If each round trip takes 100 millisecond in quick, it will take just hundred millisecond for the first request or if kleine knows the server already, it will take zero millisecond. So before we write that step, III server remember this quic is not equal to HT p3. Ok, this terms will be used interchangeably, but they are not the same. So HT p3 is the application protocol which uses quick as a transport protocol.

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So you have STP 3 on top of quick, then on top of UDP and then IP the node.js implementation will let you create your own alternative protocols on top of quick one place where we are considering using quick is for inspector protocol. We currently use WebSockets, but we may switch to quick or in Diagnostics. Similarly, you can create your own application protocol over quick, like DNS DNS, might also use quick. So let us say the STP 3 server.

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Of course, when you request slash could index. Otherwise you request the file name and you load the web page and you and you get this site can't be reached. Why? Because it is experimental. Ok, you cannot use it in production, its experimental, but we have done lot of progress. So it is an early stage of development, but you can help build it. You can help build it. You can help build it. How go to node.js with so these are progress. We currently have around 70% done, and this is the project board and this slightly outdated.

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But you will be wondering oh, like I, want to contribute. I can see all the excitement in each one of your eyes that you want to contribute to quick, but you will be wondering: oh, like I, don't know anything. How do I contribute so any easy right test start with writing unit tests. It's amazing! When you write unit tests, you'll find books and you'll fix those books, and then you can also become a collaborator like me.

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So how can I write unit text? I am glad that you asked so you gotta know just quick, you forget and then you clone it. Then you say experimental quick because it is experimental, get the coverage and these are the results slightly or old, but this is what we have for JavaScript. So, if you're into JavaScript, you can help writing unit tests in JavaScript and we need more help in writing C++ tests, because there is lot of code in C++ so so now. This is how to contribute to quick in HTTP 3.

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But if you want to go more deep and contribute to the protocol itself, then STP. The protocol is a ITA IDF draft 24 right now, so you can join the meetings and suggest so we'll just will still see an example web page on quick that is squid dot rock. So this is how it looks. So when you examine it, we will say that the protocol is HTTP, 2 plus quick. So let us go through demo. The node.js did not build on my machine.

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Quick, so I'll show the demo, which James showed so in know to confit. You.

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So this is one of our tests that we're using and I have debug tracing enabled. Basically, you just gonna see a bunch of text plant' across the screen, but it's a client talking to the server sending a copy of the test file itself back and forth. Alright, but I want to once once it's through I want to point out a few things that it are we seeing the results. So this is, you know, sending all the UDP packets.

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This is all the trace information just take just a second here, but it actually works which I'm just super happy about, because last week this was seg faulting like crazy.

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Alright, so we see here at the end when these in these objects and all this information is available to the JavaScript layer, but we have here, you know you can see the bytes sent right. You can see the number of streams that were created if you scroll up here a little bit further, we'll see that you know how many bytes were received on a particular session when it went a handshake hard to win it when it completed. This is all information.

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It's going to be available at the JavaScript API layer just built in here, so this that right now, this is information that you would have to install additional modules to get in other things with a node. This is all going to be built into the API and available.

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So, let's save a summary of what we learn in SCP 1.1, multiple TCP plus TLS connections were required for concurrent requests in SCP 2 added multiplexing, in which multiple HTTP requests were sent on the same TCP connection or disappeared off line blocking in which is is the one in which the entire TCP connection is brought to an halt. If a single TCP packet packet is lost and STP 3 over quick treats each stream independently, so that if any packet goes missing in a stream, only that stream is affected.

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That's it! Thank you for listening. My name is Sriram cometh. All the code which I showed is present on github in the slides available there thanks.