On Sunday, 23 July 2017 21:11:32 PDT 조병탁 wrote:
> Thank you for response.
>
> In my understand, iotivity has no issue when user uses iotivity open source
> as client and server. Because iotivity 1.2.(server - oic1.1) will response
> error as '4.06 Not Acceptable' about request of iotivity 1.3.0(client -
> ocf1.0). at this time, iotivity 1.3.0 will resend discovery packet
> according to oic1.1. spec. automatically.
Hmm... you're right. I was incorrect in stating the messagae would simply be
dropped. The spec is very clear: RFC 7252 section 5.4.1 "Critical/Elective"
says
o Unrecognized options of class "critical" that occur in a
Confirmable request MUST cause the return of a 4.02 (Bad Option)
response. This response SHOULD include a diagnostic payload
describing the unrecognized option(s) (see Section 5.5.2).
> But some other implementation will response '4.02 Bad Option' or will drop
> request message. in this case, iotivity 1.3.0 can not resend discovery
> request automatically.
Looks like we've been sending the wrong reply, but so long as a reply was
sent, we can detect that there's a device there and try to resend without the
version option.
Dropping the request is wrong too, against the CoAP spec. Maybe it's something
we can ask the OCF CTT to test, by sending a CoAP packet with another, unknown
CoAP header option and see if the device replies with 4.02. We should even
make it mandatory on the OCF spec to include the diagnostic payload that the
CoAP spec mentions and leaves only as a recommendation (SHOULD). That way, the
device that sent the request can quickly determine what option it was that was
rejected and, from that, conclude the age of the remote device.
> In conclusion, if someone uses other implemenation (oic 1.1), they should do
> something accoridng to version negotiation.
> and about 'Elective option' i mentioned, i've thought, there should be no
> CoAP option parsing error.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel Open Source Technology Center
_______________________________________________
iotivity-dev mailing list
[email protected]
https://lists.iotivity.org/mailman/listinfo/iotivity-dev
