5 ms·

The Harmful Consequences of Postel's Maxim

16 points by golangnews 9y ago

MichaelGG 9y ago
Look at HTTP. How many implementations correctly and interoperably handle line folding? Comments in headers? Different line endings? Stick to a small subset and you're fine. Actually use the spec as written and it is hopeless. These crazy semi-freeform text protocols are a curse. They do not make implementation easier. They trick people into thinking they made it easier.
voiper1 9y ago
I know the FOSS FreeSWITCH VoIP b2bua has a TON of "hacks" to "Be liberal in what you accept" which is a mess of things to support, to clean up after the commercial entities that don't follow SIP specs. e.g. SONUS information: https://freeswitch.org/confluence/display/FREESWITCH/RTP+Issues https://freeswitch.org/confluence/display/FREESWITCH/RTP+Iss...
gumby 9y ago
A physical world example is USB Type C: you may have a high-speed Thunderbolt drive and a high-speed Thunderbolt computer, but you may unwittingly use a cable that doesn’t support that (though it may even support some other high-speed protocol) so the whole apparatus will silently fall back to a very slow rate without informing the user. No problem for you and me, but possibly a problem for some unfortunate user. Since none of the cables or ports are visibly labeled with their capabilities you have to know what you’re doing.
- hdhzy 9y ago
  > Since none of the cables or ports are visibly labeled with their capabilities you have to know what you’re doing. I don't know about all of them but my cables and ports have visible Thunderbolt logo (small thunder symbol).
  - gumby 9y ago
    Your Type C ports and cables? What machines and where do you get your cables?
    - hdhzy 9y ago
      Dell XPS 9350 has one Thunderbolt port [0] and Dell Thunderbolt Dock TB16 has attached Thunderbolt cable [1]. I agree it's not a big, representative sample but still... [0]: http://cdn2.ubergizmo.com/wp-content/uploads/2016/02/dell-xps-13_9350_13.jpg http://cdn2.ubergizmo.com/wp-content/uploads/2016/02/dell-xp... [1]: https://i1.wp.com/geardiary.com/wp-content/uploads/2017/02/dell-thunderbolt-dock-tb16-MO-3.jpg?resize=750%2C457&ssl=1 https://i1.wp.com/geardiary.com/wp-content/uploads/2017/02/d...
      - gumby 9y ago
        That is excellent. If only more vendors (I'm looking at you in particular, Apple) would do this. The USB ss logo is absurd (not Dell's fault). Nobody knows what all those almost-identical names for different kinds of USB mean.
        hdhzy 9y ago
        > If only more vendors (I'm looking at you in particular, Apple) would do this. I'm not really using Apple cables but a quick search shows that this adapter [0] has a small Thunderbolt logo on the USB-C connector. [0]: https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-usb-c-to-thunderbolt-2-adapter?fnode=8b https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-u... > The USB ss logo is absurd (not Dell's fault). Nobody knows what all those almost-identical names for different kinds of USB mean. I agree. To one-up this on the other side of that laptop [1] is a USB PowerShare port with even more elaborate logo. It's just... super confusing. [1]: https://geardiary.com/2016/03/07/charging-usb-devices-with-your-dell-powered-off/ https://geardiary.com/2016/03/07/charging-usb-devices-with-y...

16 points by golangnews 9y ago

Look at HTTP. How many implementations correctly and interoperably handle line folding? Comments in headers? Different line endings? Stick to a small subset and you're fine. Actually use the spec as written and it is hopeless. These crazy semi-freeform text protocols are a curse. They do not make implementation easier. They trick people into thinking they made it easier.

voiper1 9y ago

I know the FOSS FreeSWITCH VoIP b2bua has a TON of "hacks" to "Be liberal in what you accept" which is a mess of things to support, to clean up after the commercial entities that don't follow SIP specs. e.g. SONUS information: https://freeswitch.org/confluence/display/FREESWITCH/RTP+Issues https://freeswitch.org/confluence/display/FREESWITCH/RTP+Iss...

gumby 9y ago

A physical world example is USB Type C: you may have a high-speed Thunderbolt drive and a high-speed Thunderbolt computer, but you may unwittingly use a cable that doesn’t support that (though it may even support some other high-speed protocol) so the whole apparatus will silently fall back to a very slow rate without informing the user. No problem for you and me, but possibly a problem for some unfortunate user. Since none of the cables or ports are visibly labeled with their capabilities you have to know what you’re doing.

hdhzy 9y ago
> Since none of the cables or ports are visibly labeled with their capabilities you have to know what you’re doing. I don't know about all of them but my cables and ports have visible Thunderbolt logo (small thunder symbol).
- gumby 9y ago
  Your Type C ports and cables? What machines and where do you get your cables?
  - hdhzy 9y ago
    Dell XPS 9350 has one Thunderbolt port [0] and Dell Thunderbolt Dock TB16 has attached Thunderbolt cable [1]. I agree it's not a big, representative sample but still... [0]: http://cdn2.ubergizmo.com/wp-content/uploads/2016/02/dell-xps-13_9350_13.jpg http://cdn2.ubergizmo.com/wp-content/uploads/2016/02/dell-xp... [1]: https://i1.wp.com/geardiary.com/wp-content/uploads/2017/02/dell-thunderbolt-dock-tb16-MO-3.jpg?resize=750%2C457&ssl=1 https://i1.wp.com/geardiary.com/wp-content/uploads/2017/02/d...
    - gumby 9y ago
      That is excellent. If only more vendors (I'm looking at you in particular, Apple) would do this. The USB ss logo is absurd (not Dell's fault). Nobody knows what all those almost-identical names for different kinds of USB mean.
      - hdhzy 9y ago
        > If only more vendors (I'm looking at you in particular, Apple) would do this. I'm not really using Apple cables but a quick search shows that this adapter [0] has a small Thunderbolt logo on the USB-C connector. [0]: https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-usb-c-to-thunderbolt-2-adapter?fnode=8b https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-u... > The USB ss logo is absurd (not Dell's fault). Nobody knows what all those almost-identical names for different kinds of USB mean. I agree. To one-up this on the other side of that laptop [1] is a USB PowerShare port with even more elaborate logo. It's just... super confusing. [1]: https://geardiary.com/2016/03/07/charging-usb-devices-with-your-dell-powered-off/ https://geardiary.com/2016/03/07/charging-usb-devices-with-y...