[le-mark]

I really wish people gave a damn about the “gui over the network” problem x11 solves. Wayland drops this use case entirely so we’re pretty much universally stuck with vnc. Microsoft rdp is a great solution for this in windows land.

[nananana9]

They drop this use-case, but still use sockets for IPC, so I still have to pretend I'm doing network programming, serialize my messages over the "network" and "flush the stream" (insanity) but don't actually get any of the benefits of this model.

I genuinely wonder if they stopped to think why X11 has sockets or just blindly copied it over. Or are they unaware other forms of IPC exist, that don't require you to go through the kernel 13 times to send a byte to the other process?

[mort96]

What would you rather they use to communicate with the server? Message passing via shared memory?

UNIX sockets are perfectly fine for IPC with small amounts of data, and is how everything in UNIX has always done it, network transparency or not. They provide a simple, efficient and reliable communication channel between two processes.

[p-o]

Wayland uses UNIX socket for message passing, but then offload most of the work to shared memory when the real work begins (GPU rendering). I just wanted to add some nuances that it's not as black and white as this comment made it seem.

[mort96]

Yeah, that’s correct; I implied it by only talking about sending small messages but it’s worth stating explicitly.

[Findecanor]

How about making the standard client library's API the interface, and have it hide whatever the system is actually using?

A long time ago when I looked at designing a X11 replacement, that was my approach. AFAIK, only special X utilities used anything but Xlib anyway. And later I think this is what early revisions of Canonical's Mir did.

[mort96]

So .. still using sockets, but not documenting how the messages on the socket look? Why?

[mjmas]

It also allows implementing a different display interface. For example Haiku OS has a compatibility layer: https://discuss.haiku-os.org/t/xlibe-an-xlib-x11-compatibili...

[to11mtm]

If I had to guess, because then at least -hypothetically- easier to optimize for the 'local' case (depending on implementation, at least from my understanding of the POSIX/*nix paradigm, bending and breaking a bunch of rules possibly) by dropping in a different implementation.

[mort96]

Optimise how? There already is only the local case in Wayland, pixel data is shared using shared memory which only works locally. Only small communication messages are sent via the socket. And the Wayland protocol also uses native endianness because, again, it only cares about the local case. It even sends file descriptors over the socket.

So what would you do differently in an alternative client library?

[dmytrish]

That's what wayland-client does.

[nananana9]

Yes, command buffers over shared memory are the correct way to do this.

  1. You don't need to convert your discrete messages into a stream with size metadata, only for them to immediately be converted to a message on the other side.
  2. You don't need to jump into the kernel to copy over 20 bytes, only for the other side to jump into the kernel to copy it back.
  3. You don't need to deal with the "oh but what if my read returns half a message because this is a stream"
  4. You don't need to pretend you're doing network programming.

Regardless, it's not that big of a deal - this is like my 73th biggest gripe with Wayland, I only mentioned it since GP was talking about network transparency.

It's pretty representative of the project though - "We're doing things the way we've always done them, but slightly different. Now rewrite all your software to work with our thing. No, you cannot do global keyboard shortcuts or set window position. You don't like it? We're doing this for free, you cannot critique it."

[mort96]

You don’t have to hit the kernel for 20 bytes. Buffer up all your commands and send them to the kernel with a single write(). The other side can then read them all (or however many fit in its receive buffer) with a single read(). The only real difference is that the memcpy happens in the kernel instead of the receiver and that the kernel provides a useful blocking mechanism by default so you don’t have to manage that in userspace code.

You need some kind of serialisation either way. It can be as simple as “this message has the shape of this C struct”, but that’s the case whether you’re talking shared memory command buffers or sending data over a socket (and there are good arguments for and against in both cases).

You’re right that you don’t need to deal with “oh I received half a message” when using shared memory command buffers, but that’s more a code complexity thing someone solves once in wayland-client and then nobody has to really think about it again. It’s not really a performance concern (because hopefully the rx buffer is large enough for it to happen rarely) or application code complexity concern.

[nananana9]

Sure. But imagine some piece of exotic hardware, e.g. computer mouse, that reports its movement at 1000Hz.

If the compositor wants to notify the client as soon as possible, it has to send 1000 messages per second. If you buffer them, you're wasting the hardware's potential, if you don't buffer, them you're doing 1000 write()s per second, which is... ugh.

If you're literally going to design the protocol from scratch and require all existing software to deal with it, why not pick the IPC model that doesn't have this issue.

[mort96]

Wait how do you solve that with shared memory command buffers? Don’t you need to involve the kernel to notify the receiver that you’ve written stuff to the command buffer?

Or would the receiver spin in a tight loop on a memory load from some byte in shared memory which indicates a new buffer is submitted, so that it gets notified without involving the kernel? Or is there some fancy mechanism I’m not aware of?

[simoncion]

> But imagine some piece of exotic hardware, e.g. computer mouse, that reports its movement at 1000Hz.

Speaking of... it looks like common Wayland compositors [0] still kill clients that can't keep up with "high speed" event generators like 1kHz mice. [1] So, that's nice.

(For people who plan to retort with "just handle events in a timely manner", check out the comment here [2]. OSX, Windows, and X11 all cope just fine with programs that go unresponsive for multiple seconds. If the statements in this bug report (and the reports I've read elsewhere) are accurate, Wayland doesn't... and that is inexcusable.)

[0] ...or whatever the Wayland terminology is for the thing that does the work of the X11 compositor + window manager...

[1] <https://gitlab.freedesktop.org/wayland/wayland/-/work_items/...>

[2] <https://gitlab.freedesktop.org/wayland/wayland/-/work_items/...>

[simonask]

Just to let you know, 1000 messages per second over a UNIX socket between two processes is very much well within the capabilities of any recent machine running, say, Linux. That’s not many at all.

[mike_hock]

> command buffers over shared memory are the correct way to do this

Sounds like a security nightmare.

[asdfaoeu]

You would have a lot of security issues right? Whether or not it's useful Wayland does prevent to isolate clients from each other.

[mort96]

They’re right on this one, shared memory isn’t some scary dangerous thing. Both processes will just have some region of their respective virtual address space which are mapped to the same physical memory, which they can use to share data. Wayland already uses this for pixel data.

[nananana9]

Not really, you can have one command buffer per client or process, and map each one in the virtual space of the process that's supposed to write to it.

[mike_hock]

A fundamental part of the Wayland protocol is passing file descriptors through the sockets so this doesn't generalize to network sockets. It also can't be done with shared memory.

[wmf]

Waypipe exists. Somebody needs to do the integration so you can run ssh -W though.

[LeFantome]

Why? Isn’t “waypipe ssh” more “the UNIX” way.

There is also wors.

[to11mtm]

> Microsoft rdp is a great solution for this in windows land.

The people who put together TS/RDP are geniuses IMO, it's insane as to how usable it has been for at least 15-ish years...

[TacticalCoder]

> I really wish people gave a damn about the “gui over the network” problem x11 solves.

Security-wise there are concerns but...

Early dial-up Internet days (early for me), 28.8k modem, I was already running Linux, probably on a 486. I also had a very old PC laptop (I think a friend of my parents gifted it to me after he got a new one from work), a 386 I think (with the horrible slow display/refresh rate: a TFT IIRC). I used a parallel cable and PLIP (Parallel Line IP) and X11 networking to send a window manager+browser from the desktop (the 486) to the laptop.

So my brother and I could both go on the Internet at the same time.

It felt like the future and, honestly, we've kinda seriously regressed when it comes to "GUI over the network".

[simonask]

Your story here also illustrates why GUI over the network used to be a much more important use case than it currently is.

These days it’s unbelievably niche, as opposed to more controlled screen sharing scenarios. I think it’s understandable that it doesn’t get a high priority.

[dannymi]

waypipe works very fine.

    waypipe ssh XXX

[ethanpailes]

https://github.com/wayland-transpositor/wprs

[ndiddy]

If you're fine with RDP, both KDE and GNOME have built-in RDP support on Wayland. If you want something closer to ssh -X, look up waypipe.

[sthuck]

I might be mistaken, but both need a physical monitor turned on. If your monitor goes to sleep you can't connect/see a black screen.

The kde one doesn't support remote user login, and while the gnome one does on paper, I never got it to work. The remote connection situation in Wayland is a major regression.

[ndiddy]

Yeah that's fair, the KDE people have remote login as a goal but it's not there yet. Waypipe is definitely the more mature option at the moment if you need a headless workflow.

[Induane]

Arcan has a decent model for this.

[LeFantome]

You can do GUI over the network in multiple ways with Wayland.

[TiredOfLife]

Sunshine/Moonlight.