Re: Seeking WebSocket proposal team

Hi all,

For me more interesting topic than specific protocol binding, would be talk
about separation of transport protocol from on wire data
format/command-message/.

Having common, transport protocol agnostic data format, would simplify
subsequend protocol binding and would be more intuitive to developers when
switching between different transport protocols. Even REST is command type
transport with trasport specific command-message structure.

Rather than asking if there is need for WebSocket binding I'd like to ask
how to structure message format to be able to map it on virtualy any
transport protocol. Transport protocols come and go based on various real
life constraints. Security considerations, HW efficiency, industry
standards, etc. I'm afraid that if there will be no common message format
someone will have to always reinvent the wheel when designing transport
protocol specific bindings.

With great oversimplification in mind, message format with operation (get,
set, invoke, subscribe), target (/throtle-move), value (20) could be sent
by HTTP, MQTT, AMQP, WS etc. Platform implementors would just need to add
thin layer of transport protocol adapters to pack and unpack common command
messages.

But this is probably selfcontained topic.

Best Regards
Robert

On Mon, Oct 24, 2016 at 8:55 AM, MEDINI LIONEL <lionel.medini@univ-lyon1.fr>
wrote:

> Dear all,
>
> >> A few years ago, we used WebSockets to control a robot through ROS and
> >> Rosbridge from a Web browser. I think WebSocket can be convenient for
> >> Web standard-compliant pub/sub across firewalls.
>
> > Firewall traversal is one of the bizarre things where WebSockets have a
> practical benefit. What you are describing would mean that you have a
> standard-compliant and globally accepted pub/sub protocol that you speak
> over WebSockets. That will then be the actual application protocol to which
> we need to map.
>
> Well, I'm not sure if it is still maintained, and neither if it is
> globally accepted outside of the "robots-over-WebSocket" community. But ROS
> (http://ros.org/) actually represents things as graphs of sensors and
> actuators that you can access in pub/sub. Rosbridge (http://wiki.ros.org/
> rosbridge_suite) provides a binding with the WebSocket protocol. The
> Rosbridge protocol is specified here: https://github.com/
> RobotWebTools/rosbridge_suite/blob/groovy-devel/ROSBRIDGE_PROTOCOL.md
>
> BTW, it's pure JSON. As far as I know, no JSON-LD context has been written
> for it so far.
>
> Best,
>
> Lionel.
>
>
>

Received on Monday, 24 October 2016 08:03:02 UTC