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Tangent: What are people using for thin clients / terminals? E.g. stuff that is deployed at e.g. airport displays for showing connections flights or self servi

Tangent: What are people using for thin clients / terminals? E.g. stuff that is deployed at e.g. airport displays for showing connections flights or self service cash-registers? Linux seems like the obvious choice as a base OS. However, running X+Firefox ontop of it seemed too clunky (slow) and unrelieable to me? - How do I make sure you recover from crashes reliably? - How do you secure the inputs, to avoid escapes from the application?

navaati 6y ago
That’s part of the "embedded computing" problem space, and people have been doing stuff like developing Qt application running as a systemd service and directly hitting DRM (the kernel graphical API), so no X, said application being mostly just a webview tailored to your use case. In addition to the webview you could imagine adding an HTTP endpoint to your application for monitoring and remote control, that kind of stuff. I say Qt because it’s popular in the embedded space, and indeed makes doing that kind of stuff easy (by example by having a DRM backend).
SyneRyder 6y ago
Considering the times I've seen airport connecting flight displays replaced with bluescreen "Your Windows 7 PC is out of support", shopping mall digital ad displays showing that a QuickTime 7 & iTunes patch is available, or the self-service grocery shopping terminals displaying a Windows XP style "Ethernet cable is unplugged" notification, I'd guess not as much thought is going into those kinds of concerns as we might like. I think I have heard of some retail chain stores using FreeDOS with a dedicated keyboard-driven accounting package to run the business, though. (In this case I'm thinking of one of the larger Luxottica owned optometry chains.)
yellowapple 6y ago
I feel like most of the corporate world is gravitating toward web interfaces. Works great for me, since then a "thin client" can be as simple as a stripped-down Linux running a Qt5 or Electron app (or a browser in kiosk mode) that does nothing but access that web interface (or perhaps has a couple different tabs for different systems). For actual thin-client needs, it seems like Citrix XenDesktop is the go-to nowadays. Linux as a base OS works okay for this (there are Linux ICA clients). Linux also has RDP clients for Windows terminal servers (or hell, even Linux terminal servers with an RDP server; I typically do this for openSUSE servers in corporate environments where the people doing day-to-day maintenance are used to Windows and insist on a GUI). > How do I make sure you recover from crashes reliably? Just restart the app. > How do you secure the inputs, to avoid escapes from the application? With a stripped down environment the only such escapes are ones you configure yourself. X11 and the session thereof can be configured to have zero options besides starting up your chosen application. Even if you leave Ctrl-Alt-Backspace enabled, it'd just boot right back into that app. Ctrl-Alt-F(whatever) (if still enabled) should present a login prompt, so unless the password's compromised you're good to go there, too. Then it's just a matter of locking down the app itself, which again is straightforward if the session is configured to just restart the app if it closes/crashes. A custom application (say, a Qt5 app doing nothing except presenting a WebEngine widget and perhaps some support for hardware interfacing) offers fewer escape opportunities than, say, a generic browser in "kiosk mode".

navaati 6y ago

That’s part of the "embedded computing" problem space, and people have been doing stuff like developing Qt application running as a systemd service and directly hitting DRM (the kernel graphical API), so no X, said application being mostly just a webview tailored to your use case. In addition to the webview you could imagine adding an HTTP endpoint to your application for monitoring and remote control, that kind of stuff. I say Qt because it’s popular in the embedded space, and indeed makes doing that kind of stuff easy (by example by having a DRM backend).

SyneRyder 6y ago

Considering the times I've seen airport connecting flight displays replaced with bluescreen "Your Windows 7 PC is out of support", shopping mall digital ad displays showing that a QuickTime 7 & iTunes patch is available, or the self-service grocery shopping terminals displaying a Windows XP style "Ethernet cable is unplugged" notification, I'd guess not as much thought is going into those kinds of concerns as we might like. I think I have heard of some retail chain stores using FreeDOS with a dedicated keyboard-driven accounting package to run the business, though. (In this case I'm thinking of one of the larger Luxottica owned optometry chains.)

yellowapple 6y ago

I feel like most of the corporate world is gravitating toward web interfaces. Works great for me, since then a "thin client" can be as simple as a stripped-down Linux running a Qt5 or Electron app (or a browser in kiosk mode) that does nothing but access that web interface (or perhaps has a couple different tabs for different systems). For actual thin-client needs, it seems like Citrix XenDesktop is the go-to nowadays. Linux as a base OS works okay for this (there are Linux ICA clients). Linux also has RDP clients for Windows terminal servers (or hell, even Linux terminal servers with an RDP server; I typically do this for openSUSE servers in corporate environments where the people doing day-to-day maintenance are used to Windows and insist on a GUI). > How do I make sure you recover from crashes reliably? Just restart the app. > How do you secure the inputs, to avoid escapes from the application? With a stripped down environment the only such escapes are ones you configure yourself. X11 and the session thereof can be configured to have zero options besides starting up your chosen application. Even if you leave Ctrl-Alt-Backspace enabled, it'd just boot right back into that app. Ctrl-Alt-F(whatever) (if still enabled) should present a login prompt, so unless the password's compromised you're good to go there, too. Then it's just a matter of locking down the app itself, which again is straightforward if the session is configured to just restart the app if it closes/crashes. A custom application (say, a Qt5 app doing nothing except presenting a WebEngine widget and perhaps some support for hardware interfacing) offers fewer escape opportunities than, say, a generic browser in "kiosk mode".