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> It's what home routers and similar devices ought to be running instead of Linux.

It's what professional routers do run. Well, some of them at least.

We used QNX at my last company, which made high-capacity IPSec gateways. We had control-plane boards and data-plane boards, with inter-board redundancy, which meant that if there was a failure on one of the boards, a standby was ready and functional within seconds.

Part of this was thanks to QNX's QNet, which made IPC transparent over the internal IP network of the system. You could launch and control processes on any other CPU running QNX+QNet, a "node" in the sytem.

It was very cool, and I miss it a bit. I certainly loved being able to kill and restart drivers, which were of course user-processes (QNX is a microkernel OS). Since I was doing driver development work, that was useful ;)

I find a lot of similar joy working with Erlang.

Having a proper (intra-application) messaging system makes a certain class of problems -- problems that you just get used to in Java, and Go, and Rust, and C/C++, and whatever -- just go away.

>Having a proper (intra-application) messaging system makes a certain class of problems -- problems that you just get used to in Java, and Go, and Rust, and C/C++, and whatever -- just go away.

Interesting. Examples?

While I haven't used Erlang, I have used other systems with nice messaging systems (PX4 autopilot and ROS) so I will try:

1) Data is passed between threads/processes using a message bus (essentially, a queue). This means, no need to synchronize data access, as every subscriber gets it's own message copy.

2) Suddenly, you need access to certain data from another module. If the program was architected as regular class hierarchy, you would somehow need to pass the reference to that required class instance or use a global function call. If there is a message bus where the required class is already publishing messages, you can simply subscribe to data from the required module and it is delivered via message bus.

3) You can replace modules easily. The only interface to other modules is via message bus, so you can replace the module with one that publishes the same type of messages.

4) If the message bus is designed correctly, you can move the modules/process to different machines, and they can access the message bus over network. Bus broker just sends the messages over TCP instead and that is totally transparent for both involved nodes.

Btw, I am still looking for an infrastructure library just like that: https://news.ycombinator.com/item?id=14222202

I don't have much experience in the field. Are you searching for something like Apache Kafka?

On the web page it states that Apache Kafka is a distributed streaming platform.

  Kafka has four core APIs:

    The Producer API allows an application to publish a stream of records to one or more Kafka topics.
    The Consumer API allows an application to subscribe to one or more topics and process the stream of records produced to them.
    The Streams API allows an application to act as a stream processor, consuming an input stream from one or more topics and producing an output stream to one or more output topics, effectively transforming the input streams to output streams.
    The Connector API allows building and running reusable producers or consumers that connect Kafka topics to existing applications or data systems. For example, a connector to a relational database might capture every change to a table.

The problem with projects like Kafka is that they are geared towards cluster scenarios on beefy machine and cannot be embedded in other projects and used as a message bus.

An example for which Kafka is not a good fit: embedded system which reads a few sensors and does a bit of image processing. Such a system should really be compiled to one or multiple native binaries and does not really need JRE.

I built something very close to this but it's closed source and very unlikely to ever be released as open source. But it's doable. About 4 man-years of work.

Very interesting; thanks. Reminds me vaguely of CORBA.

Which professional routers? Cisco doesn't use QNX and Juniper uses FreeBSD. I'm not sure there are any other router manufacturers that matter.

> Cisco doesn't use QNX

Other than on their most expensive, powerful routers.

https://en.wikipedia.org/wiki/IOS_XR

Wow, I forgot that even existed. Here I was thinking of every switch, firewall, and routing product they've done except this line. I guess it doesn't help that I've never had a reason to touch one as every carrier grade router I've used has been Juniper. I wonder why they went with a whole new platform based on QNX when you don't benefit from a realtime OS if all the packets are moved in hardware? Must be something about the pain of upgrades and reloads on other Cisco product lines and somehow QNX can minimize these outage windows.

I've still yet to meet someone who actually prefers Cisco over Juniper MX. I wonder who is buying these?

"I've still yet to meet someone who actually prefers Cisco over Juniper MX. I wonder who is buying these?"

You have met my ex-boss.He had no reason to necessarily prefer Cisco other than that's all he was accustomed to.

But how do you get "accustomed" to it when every OS Cisco has looks the same but is different enough to drive a man insane?

It's a highly-reliable, ultra-responsive, self-healing OS w/ plenty of middleware and supported architectures. Also easy to develop on. It's already 90% to their goal for their OS and software. Why not use what already works? If it makes them enough money, they could try to develop something similar in-house.

EDIT to add jacquesm's comment:

https://news.ycombinator.com/item?id=14231160

Mine on Lobsters summarizing a lot with links:

https://lobste.rs/s/ensbd6/building_blackberry_qnx_7_desktop...

During college, I was hired by a small company that specialized in QNX based software to port several Unix utilities (I remember porting finger and at least one other program---I don't recall). It wasn't that bad as its POSIX support (even in the mid-90s) was pretty good.

What really blew me away about QNX though, was that the network was invisible. You could construct a command line on machine A, to run a program on B with a file on C, redirect the output to a program on D with that output going back to A. My boss, sitting in the office next to mine, would run a communications program on his system while using the modem connected to my computer. Wild stuff.

I also had a friend that owned a software company selling commerical X Window servers for a variety of systems. Their fastest version ran on QNX.

I think, you could do that easily using ssh with Linux.

  program1 | ssh server1 program 2 | ssh server2 program3

It's not exactly because ssh can't forward `/dev/ttyS0`

It takes more than someone just adding a special adapter to produce such an interface, because you also have to change all of the modem applications that consume the `/dev/ttyS0` interface to also consume the unix-domain or TCP-based interface.

Meanwhile with Qnet, an application simply goes open("/net/node1/dev/ser1") and gets the modem attached to node1. Plan9 has a similar capability.

Would not surprise me if the GNOME people find a way to replicate that using dbus and their VT backend.

Oh my... dbus something like OLE2/ActiveX, just 10 years too late and full of XML.

Linux has 9p2000 support, I've never heard of people actually using it to export devices over the network though. Fuse also has support for ioctls and other weirdness so it's not impossible for something like sshfs to forward /dev over the network.

no.

Oh wow you're right! I don't know where I got the idea that fuse handled ioctls from.

For what it's worth, there's a network block device over 9p: https://github.com/chaos/9nbd

It's not at all the same thing, and not as transparent. But just in case someone reading wanted to do remote serial ports on Linux, there is rfc2217 and virtual serial ports. There's a program called ser2net that can bridge them for any program. Also, most serial port oriented software like miniterm, pyserial, etc, has built in support.

Wow. So basically Plan 9 resource sharing, ported to the real world (ie something that's usable without modification or special consideration).

D:

> It's what home routers and similar devices ought to be running instead of Linux.

The bummer is that it's not FOSS.

Well, one day gnu/hurd will be the FOSS system we all deserve.

The bummer for the companies doing the home routers is really just that it costs money. The only people who give a flying fsck about the F part are hobbyists, sadly.

Source: worked in this industry.

Not having a hobbyist option, means there are fewer people trying to use it for new and interesting things.

Funny there doesn't seem to be an OSS attempt of something like it... ( Or my google-fu is weak )

Google Fuchsia is a capability-based, real-time operating system (RTOS) being developed by Google.

https://en.wikipedia.org/wiki/Google_Fuchsia

15 years ago I waited for GNU Hurd, but now I am very interested how Google Fuchsia turns out. What I read it shapes up nicely, and I can imagine we all will use it in near future instead of Windows and other binary blob legacy operating systems; it might also replace Linux as Android kernel - but that is still just speculation.

That's going to be interesting. Some of the people at Google working on it are ex-QNX people.

Oh hell. I was initially skeptical but my hopes are up now that you say that.

I know some are ex BeOS people, but I haven't heard of anyone from QNX on the project. Apple did hire the founder of QNX not too long ago, though.

FreeRTOS is here: http://www.freertos.org/

Though the "RT" is the only real overlap. It's targeted more at lower end hardware, but does have an x86 implementation.

Minix 3 for reliability part, DROPS for real-time part, OKL4 for mobile, and Genode for security part are basically it that I'm aware. It's really the mix of capabilities in one system that makes QNX great. I don't know anything that has that despite the architecture described in great detail in freely-available papers. Just waiting to be cloned or improved on. :)

http://www.minix3.org/doc/reliable-os.pdf

https://os.inf.tu-dresden.de/drops/overview.html

http://l4hq.org/projects/kernel/

https://genode.org/about/index

> "google-fu"

nice combination!

I wrote a QNX clone (32 bit when QNX was still 16 bit) and it was meant to become open source but that never happened. One of the most interesting projects I've worked on.

>all of POSIX is available

That's nowhere near enough for application development in 2017, POSIX is nice, but it's the bare minimum - kind of like WTO rules for international trade, nice baseline, but you still want better deals with individual countries.

> It's what home routers and similar devices ought to be running instead of Linux.

Given that QNX is closed source, the state of BlackBerry, the NSA leaks, the subversion of BB Messenger security etc., I'd contest whether that's a good idea.

> The desktop environment had very consistent performance, because QNX doesn't swap. (It's a real time system, after all.)

Is it possible to configure Linux towards this sort of behavior? I disabled swap, and whenever my memory is exhausted aggressively (think a runaway program writing to /tmp, which is on tmpfs), my system comes to a grinding halt.

How does QNX deal with memory pressure?

In the Photon GUI, there was a bar at the lower right of the screen showing how much memory was in use. If you tried to start a program and it wouldn't fit, you got an error message. Existing programs continued to run, but requests for more memory might return an error. In the real time world, you don't ask the OS for memory after startup for anything critical.

> In the real time world, you don't ask the OS for memory after startup for anything critical.

What?

Dynamic memory allocation is frowned upon in both embedded and real time environments.

That makes sense, but I've never understood "the real world" to be a metaphor for those environments.

He said "real time world"

> It's much simpler and saner than Windows or Linux.

So true. This is why Genode OS is grabbing my interest these days.