Adding Websocket support to core

[MylesBorins]

The original thread where adding this was discussed #1010 was closed with a decision by the iojs TC to rather implement lower level buffer methods, but that was abandoned.

There is an open EPS to add the feature, but we have since abandoned the process.

Some of the people who originally were -1 changed their opinions in #1010 more recently. In fact, we already ship a partial implementation of ws in the inspector.

I think it might be worth us revisiting adding WS to core.

/cc @eugeneo @rauchg

[eugeneo]

Re: Inspector.

1. Inspector WS implementation is not complete, e.g. there is no support for binary frames.
2. Inspector would still need a C++ implementation that can run on a separate thread. Both JS execution and main libuv loop are suspended when the application hits a breakpoint.

[devsnek]

i'm not wholly against this but i would like to factor in how much stuff we put into all our release binaries. if we can come up with more creative ways for shipping stuff like this i'm totally a +1 (#19307)

[mscdex]

I am still -1 on this.

[devsnek]

@mscdex can you be explicit in your reasoning?

[mscdex]

@devsnek for the same reasons I gave in the linked issue.

[lpinca]

As discussed in #1010 and as a maintainer of ws I'm +1 on adding WebSocket to core.

[MylesBorins]

@mscdex in #1010

-1 WebSockets is still something better suited for userland IMHO. Sure it's something that many people do use, but there are also many other widely used standardized protocols/APIs that could be argued as "core" to the "web" that are not currently included in node/io.js core. For example: multipart parsing/generation, Server-sent events, HTTP/2, ICMP, SSH/SFTP, FTP, SOCKS, VNC/RFB, SMTP/IMAP/POP3, SOAP, Web Workers (as an API), XHR/XHR2 (as an API), etc.

Since this original post we've added http2. While you listed a bunch of protocols not all of them are supported natively by the browser.

https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API

https://caniuse.com/#search=Websockets

[mscdex]

@MylesBorins I don't think node should aim to become a (DOM-less) browser. Anyway, my "vote" and reasoning still stands.

[targos]

It's more about communicating with browsers, not becoming one.

[bnoordhuis]

http2 is an argument against being too eager to absorb protocols into core. Neither its API nor its implementation are all that great; it would have benefited from iterating outside core for a while.

I guess you could construe that as an argument in favor of websockets: third-party modules have existed for years and their APIs and implementations have pretty much crystallized by now.

[brianleroux]

This is a great idea. While today Node is already an indispensable tool for web developers it does not enjoy the same full seat at the table of web browser tech advancement despite being held completely captive by it. Few agree on the controversial edicts like Promise and esmodules but we can definitely all agree these transition moments could have been handled better with Node being an a fully active participant instead of recipient of these challenges.

Node has a big opportunity to become a full fledged user agent (web browser) and first class support for web features will be a part of that. +1!

[jasnell]

http2 is an argument against being too eager to absorb protocols into core. Neither its API nor its implementation are all that great;

PRs welcome.

Re: websockets

I'm still -1 for the time being. This is something that has been done quite well by userland and there are still unanswered open standards questions about http2+ws that require more thought and experimentation.

[watson]

When http2 was added, I think one of the considerations were that we could do a lot of low level stuff in C++ land that was hard or even impossible(?) to do efficiently in user-land. Is there a similar reason for wanting to bring WS into core, or is it just to have more features?

[MylesBorins]

@jasnell can you point me towards the open standards discussion regarding h2 + ws?

[jasnell]

The ietf httpbis working group is working on this .... https://tools.ietf.org/html/draft-ietf-httpbis-h2-websockets-00

It's still super early in the process tho there is some early implementation happening.

[kof]

Ideally there should be a clear general framework on how to decide whether something belongs to the core or not. I would consider points like

• is it hard to be done right?
• is it widely used?
• does it have a clear spec?
• is it likely to become obsolete in the near future?
• does it need optimizations from the core?
• will the entire community benefit from it being part of the core?

[addaleax]

is it hard to be done right?

@kof I fully agree with all your points except this one – there is no reason to believe that code in Node core is better-written or better-maintained than userland code in general.

I think a better question in its place would be “Is it hard to do effeciently without native addons?”.

[kof]

@addaleax The idea behind that point is: if it is in userland, it is likely there will be multiple competing implementations, which will result in attention not being fully focused on a single code base and as a result lower quality, just because less people are working on it or using it. I have no data to back it up.

Userland is good when a feature needs experimentation.

[lpinca]

@kof

is it hard to be done right?

No.

is it widely used?

Yes it is.

does it have a clear spec?

Yes.

is it likely to become obsolete in the near future?

No.

does it need optimizations from the core?

Not necessarily but optimizations in core may help. In ws we have two optional binary addons. One for the masking/unmasking of frames (bufferutil) and one for the UTF-8 validation (utf-8-validate).

will the entire community benefit from it being part of the core?

Yes I think the community will benefit from WebSocket in core.

There are a lot of userland implementations. The most popular are ws, faye-websocket, and websocket. Combining the the best parts of each one of them to create a single module in core would be great imho.

[mcollina]

+1, mainly because @lpinca has been doing a great job in maintaining ws the last few years.

[MylesBorins]

pinging @jcoglan and @theturtle32

[watson]

So far I haven't seen any concrete comments on why implementing WS in core would be better than having it in user-land. I'm sure @lpinca have done a great job maintaining ws, but that hardly qualifies as a reason to bring it into core right?

I just think there need to be concrete examples on how core can provide a better WS implementation than user land 😃

[devsnek]

i don't think there's anyone saying we would do a better job. i think the argument is better integration and since we can ship it with a native backing users will get a perf boost without having to install anything.

[watson]

@devsnek Could you provide an example of how the integration would be better if WS was in core?

Regarding native backing then n-api and pre-compiled binaries should remove the requirement of having users compile stuff (if I understood your argument correctly).

[TimothyGu]

It seems the main argument for adding ws to Core is to reduce binary dependencies. Since both native dependencies are buffer-based, I think they may be good candidates for adoption of WebAssembly. @lpinca has that been seen as a possibility?

[MylesBorins]

For an API, I'd like to propose the WhatWG WebSocket API, as much as we can implement the standard (I know there will be some inconsistencies around events).

If we run into any serious problems with the API design we can attempt to work with the whatwg to update the standard. It seems like @TimothyGu has participated in this document along with @domenic.

re: http/2 + ws, if we get an implementation going we can participate in trying to solve this problem!

will the entire community benefit from it being part of the core?

I think implementing standards in core, especially ones implemented in the webplatform, can help the ecosystem focus on creating better abstractions on top of a protocol like WS, and avoid having to implement the base protocol themselves. If the various ecosystem modules share a kernel it allows there to be collaboration across projects with a shared interest, and potentially brings more people to help maintain core itself.

[lpinca]

@watson userland implementations work and I'm a big supporter of small core but HTTP(s) and many other modules are in core because they are so popular that it made sense to create a core module for them. The same is valid for WebSocket in my opinion. Quoting @domenic from nodejs/NG#10 (comment)

I think the conclusion of this line of thought leads us to a process wherein we say "yes, core is interested in supporting feature X." Then, someone---maybe an io.js collaborator, or maybe not!---goes off and builds a prototype of feature X as a user-land module. Along the way, they might need to ask for more low-level APIs from core, and those will get rolled in. But over time, this external implementation of feature X matures, and io.js collaborators start commenting on it, and the ecosystem starts using it, until we decide: yes, we should roll this in to core, and start shipping with it.

Is core interested in supporting WebSocket? That's an open question. I think it should.

@TimothyGu we didn't explore that possibility but that's definitely a good idea. We already have prebuilt and n-api based binaries for native addons. Removing binary dependencies is not the reason why I would like to see WebSocket in core though. The question is, why is HTTP and HTTP2 in core and WebSocket isn't? They all are in the same league and they all can live in userland if wanted. On top of that a good part of the WebSocket implementation is already in core as the upgrade mechanism is already available and supported in core.

@MylesBorins If we ever decide to experiment with WebSocket in core, API need to be discussed. I think we want to support piping data around so a websocket should be implemented as a Duplex stream like faye-websocket does. I guess we also want to support fragmented messages and permessage-deflate. In this case we should augment the standard send() to add the ability to specify if a message is the last one in a fragmented message and to specify if a message should be compressed or not.

[M3kH]

I can't establish a vote for this, although would be a nice to have.

I found that WebSocket implementation isn't that solid neither in the Browser.

Is high cpu consuming and so far I couldn't see any implementation in a big scale (which I would have guess they would be using it); eg: Facebook, Twitter and Gmail, they rather relay on polling.

I guess is mainly related on the cost created on the Server side due being really hard to scale it (eg. Load balancing). Not sure Node wants to make his capacity in supporting it.

[jasnell]

And when I say 'users' I mean real users. With http2 and n-api virtually no one but the people working on it used it or even knew it was in the works until it was released.

This is entirely incorrect.

Even so, we seem to be in agreement that starting work within a separate repo is the right approach.

@MylesBorins ... I can create the repo under the nodejs github repo if you'd like, or I can leave it to you. The folks who are most interested in moving this forward can decide on the best work mode for them -- including whether that repo is a fork off core master or implemented as a separate module at first. Once some concrete progress is made there, let's revisit the question about whether it should land in core. I have created the @nodejs/websockets team and added you (@MylesBorins) as a maintainer.

[bnoordhuis]

Strong riposte, James. I suspect you get defensive because I brought up http2 but I'm merely using that as an example of where we (note the 'we') could have done better. Let's learn from our mistakes.

[ofrobots]

Core has more supporting infrastructure for new code to piggyback on but there is little that you can't also do from a native module.

One thing I would like to point out about native modules is that they have a significantly worse user experience for end-users. Users have to provide a compilation environment in their deployment environments; or trust a binary blob – which typically is not available for all platforms. Even if a module could be built to be just as efficient as a native module, it still wouldn't have the same first class user experience.

If it is deemed that protocols like http2 and WebSockets are central to The Web, then we should not relegate them to a less than ideal user experience.

[lpinca]

@watson I don't know, I think a pure JS implementation that resorts to low level stuff for computational intensive operations will not be much better than a userland implementation that does the same thing. My main reason for having WebSocket in core is not performance which is always good to have but to improve ecosystem interoperability.

[bnoordhuis]

One thing I would like to point out about native modules is that they have a significantly worse user experience for end-users.

I agree. I advocate them as a stepping stone to built-in support, not as the eternal status quo.

That said... stuff like websockets and http2 would make interesting webassembly case studies.

[rauchg]

My opinion is that WebSocket should be in core. Node.js was designed and has thrived as a platform for writing network services.

If I were learning Node.js today, I'd expect that network protocols that are widely deployed, have formalized specifications and fit the purpose of the platform would be supported out of the box.

I've expressed similar sentiments over the last couple years with regards HTTP/2[1], so I'm thankful @jasnell and others have done such an amazing work there.

I think a websocket server and client can be specially beneficial if:

1. we can get demonstrably higher performance than userland implementations that don't build native addons
2. we can expose primitives that could aid userland modules, like a reusable parser! Userland would get even better, fostering experimentation, like transporting the websocket protocol over non-HTTP channels

All in all, I'm very positive on this. The first version of socket.io had to be distributed with a .patch file to hack Node.js core to make WebSocket (Upgrade in general) work properly. Node.js is a great platform for experimenting and prototyping new ideas like that, and having solid building blocks in place from the start is a huge win.

[1] Specially after wrangling with the numerous bugs in userland implementations. These protocols are hard to get right!

[shellscape]

Given the wide adoption of the client spec in the last two versions of nearly every major browser necessitates the adoption of a per-spec implementation in core. The performance benefits alone will make us rich beyond the dreams of avarice. But please for the love of all that is holy, stick to the spec and avoid anything, literally anything that diverges from the spec.

[kapouer]

My opinion is that WebSocket should be in core as well, and that uws has been a game changer for many developers because it brought high performance: think about serving hundreds of thousands simultaneous clients with node+uws on a single cheap server.
I would add on top of what @mikeal said, that my vision of Node.js is that it will die and be replaced by browsers in a foreseeable future. It's not browser without DOM it's cutting-edge browser with optional optimizations for servers.

[d3viant0ne]

Agree with @rauchg - WS usage is definitely on the rise which imo coincides with the push to not pull shift in delivery ( WS & Socket.io alone are pulled 20 million times a month ) & as @shellscape mentioned, the browser adoption is wide.

An on spec native implementation can only help further adoption & performance while giving user land a single way of implementing WS easily. All of these things would be extremely beneficial to NodeJS consumers particularly since as @3rd-Eden said, we really can't push the performance much further without WS becoming part of Node.

As @eugeneo & @3rd-Eden already pointed out, Node technically already as a degree of WS support, this could be expanded upon to bring this feature home.

[talamaska]

I can't believe how much people are against Web Socket implementation in node, and even not happy about http2?
What the hell guys? Node was supposed to be cutting edge, now years after first WS implementations, Node still don't have it, and please don't tell me to use any of the ready made ws socket frameworks. I hate them. I used ws module way back and I was happy with it.
What about http2? This was long awaited upgrade, something that helps PWA become first citizen on mobile.
I don't get it, every one of those spec is finalized, really a straight forward implementation in the lower level of the node code on C++.

[bnoordhuis]

@talamaska What makes you think you'll like the built-in websockets module better?

Note that I'm personally (mildly) in favor but the argument against adding it is that design mistakes in core modules cannot be fixed easily without breaking large swaths of third-party code.

Third-party modules don't have that problem: fix flaw, bump major, move on.

[ThisIsMissEm]

As the author of one of the earliest websocket modules (which I've since decided shouldn't be used in favour of ws, websocket, faye, etc), I would say that we've already had to make special changes to core's http module in order to support websockets: now that they are a formal specification, I see no reason that they shouldn't be entirely in core.

I agree with @3rd-Eden and @rauchg, particularly with exposing some lower level primitives that could be used to build custom websocket-based protocols. I wouldn't argue for all protocols to be build into Node.js, but web-native protocols make sense: they fit with how most people use node.js, they're expected.

I for one fully support the idea of making Websockets part of node.js core (though, let's skip the Global)

Aside: On http2, whilst I've not followed fully, it sounds like it could've benefited from being non-core for a little longer, but that's an entirely separate discussion.

[nicolasnoble]

Cross referencing bugs here: introducing websockets into the core could potentially help with issues like socketio/socket.io#3212 in the long run, where people are relying on binary extensions to improve websocket speed - which is evidently not a good idea.

[bertolo1988]

In the long run aren't users going to prefer http2 streaming capabilities over websockets?

[josephg]

Huh? I haven't read anything to suggest that http2 will supersede websockets. http2's streaming is bidirectional but not symmetric - only the client can initiate requests. Unless something changed recently, server side push doesn't bubble responses up to JS code. Also (afaik) just like http, http2 doesn't make any guarantees about preserving the order of client->server messages.

You could implement your own message-oriented streaming protocol on top of http2 using POST messages for C->S and server-sent events for S->C. But you will have to implement your own message ordering code. And you'll have load balancer problems. Websockets are sticky-by-default. That is to say, if you have a cluster of frontend servers with a load balancer, a websocket connection will stay connected to a single frontend machine for its lifetime. Configuring load balancers to replicate that behaviour on top of normal http requests is a black art. Corner me in a bar sometime and I'll tell you all about the nightmares we had getting sticky sessions working correctly through ELB a few years ago. (I understand some libraries try to silently migrate sessions. This introduces its own concurrency problems, and it doesn't work for all use cases.)

So, no. In the long run I hope websockets are reimplemented on top of http2. Although to be honest most of http2's benefits won't make much difference for websockets anyway. Over http2 the initial WS connection & handshake will be faster (since it can reuse the TCP connection it loaded the page on), but once its established it won't really matter. When websockets are implemented in http2, it will still make sense to have websocket code inside nodejs.

[arxpoetica]

[@theturtle32 said:] I don't feel it's anywhere near as widely used or fundamental as HTTP is, and it would end up just being more for the core team to have to maintain.

As others have pointed out, adoption is actually high.

[@josephg said:] will the entire community benefit from it being part of the core? (no - websockets are used widely but still only in a minority of projects)

This is a false negative; it may be a chicken and egg scenario where adoption seems lower (it's not) because the tooling is not easy to use and natively available. I personally believe this to be true. Adoption will be much higher with the right low-level API.

[@josephg said:] Personally I think there's a middle-ground that I'd like even better: Have an official list of recommended solid, default modules for specific tasks in nodejs. These could be decided on however we like. The official documentation should list these modules.

Off topic, but it could easily solve the "should we" paradigm. Too much to say on that here. Can it be picked up elsewhere?

[@mikeal said:] Node.js adopting new core protocols of the Web is perfectly in-line with its original vision and only a dogmatic originalism could argue otherwise. There may be perfectly good technical reasons not to include Web Sockets but the argument that it is somehow out of scope doesn't match the history or vision the project has had since day one.

EXACTLY this.

[@rauchg said:] My opinion is that WebSocket should be in core. Node.js was designed and has thrived as a platform for writing network services.

As someone who has had to implement WS on a few different projects, I am certain of two things: usage will increase dramatically over the coming years by particular verticals (storytelling engineers, for one). As well, WS are never easy to use. As @mikeal said, one of the things Node.js has had going for it from the beginning was the sense that it was built to be interoperable with the browser. Java, Ruby, Python, Go, and all the other low-level languages have never been easy to work with in terms of browser interoperability, and one of the explicit reasons is the difficulty in interacting with basic protocols such as http. Userland has built up a nice ecosystem around WS, but the tooling and ease-of-use factor is still a hell-a-difficult.

Treat WS as the first-class citizen it deserves to be treated. This should have been done 5 years ago.

[galvez]

Treat WS as the first-class citizen it deserves to be treated. This should have been done 5 years ago.

Especially with the growing popularity of WAMP-based apps.

+1 on this.

[GrosSacASac]

From the about page

About Node.js®
As an asynchronous event driven JavaScript runtime, Node is designed to build scalable network applications.

Node should definitely have a WebSocket support and Server-sent Events, TPC, UDP, HTTP, HTTP2.

[dipser]

A lot of IT-student in germany have to write websocket-applications. From this standpoint alone, it should be native. nodejs feels incomplete, if it isnt. You just use it natively in a browser, but in node.js you first have to find out, its not supported, then you have to decide which userland implementation is ok and future proof? At this point, i would be annoyed. Because you will feel like nodejs is not the wonderland of server-communication you thought. The next thing as student is, you have to deal with a callback hell. How many give up at this point? Let alone, that javascript wasnt very loved in the past, but is developing (ES6) very fast and has the big advantage of learning only one language in front- and backend. If that wouldnt be the case, nodejs would have died long ago - but thats just my impression.

[damianobarbati]

Treat WS as the first-class citizen it deserves to be treated. This should have been done 5 years ago.

Definitely.

[bradisbell]

I have strong opposition to this. Node.js is used for far more than web applications. Adding bloat to the core hurts these other types of applications and their portability, while providing no significant benefit to those who want it. Keep Node.js light and keep WebSockets in solid modules like ws.

[galvez]

@bradisbell you have a valid point -- I just think WebSockets can be considered a core protocol of the web, very much like http2.

[arxpoetica]

@bradisbell this is probably the most valid point I've heard on this.

I would favor, alternately, some sort of tree-shaking methodology native to Node in that case. I.e., only import what's actually imported. Obviously waaaaaay beyond the scope of this ticket (how would such a thing even be possible), but that would be my 2 cents. Best of both worlds, actually. Significantly lighten Node core, but still have core/official requires available on demand.

[josephg]

What is the actual decision making process for a big change like this?

It'll be controversial no matter what the decision is. But it would be nice to have a clear official resolution on which way node will move forward with this. Can we bump this to the TC or something?

[devsnek]

there's nothing stopping someone from making a pr. if that pr was blocked for a non-technical reason (like "ws shouldn't be in core") it could be elevated to the TSC

[gengjiawen]

@lpinca Mind create a PR ?

Just found go has websocket too https://godoc.org/golang.org/x/net/websocket.

In js ecosystem，new api System like Graphql subscription rely on this: https://github.com/apollographql/apollo-server/blob/678714293337be19163e7ae0f973c6d873cf3656/packages/apollo-server-core/package.json#L46.

[feross]

FYI everyone: There's a new spec WebSocketStream that is intended to supersede WebSocket in the same way that fetch superseded xhr. The new spec supports backpressure.

If the decision is to add ws to Node.js, then perhaps we should skip the current API and just implement this new one, since backpressure is quite important. https://groups.google.com/a/chromium.org/forum/m/#!msg/blink-dev/X7rWpAkMCyg/j6K7mEEwAgAJ

(We should also wait until this API stabilizes and there is buy-in from other browsers besides Chrome)

[lpinca]

FWIW I've recently added in ws a utility function to wrap a ws WebSocket in a Duplex stream with full backpressure support.

• https://github.com/websockets/ws/blob/master/doc/ws.md#websocketcreatewebsocketstreamwebsocket-options
• https://github.com/websockets/ws#use-the-nodejs-streams-api
• https://github.com/websockets/ws/blob/master/lib/stream.js