Conflict between Write(Update)/Create and Write(Update)/Execute about oma_lwm2m_for_developers HOT 11 CLOSED

These points will be addressed (and solved :-) ) in August.
According to my view :
a) For the execute : if the spec fixes (Appendix D) the fact that the operations a resource can support are R(Read only), W(Write only), RW (REad and Write) or E (Execute)
then a POST on a resource is not ambiguous any more : a POST on a Resource supporting 'E' operation is an EXECUTE, a POST on a Resource which doesn't support 'E' operation is a WRITE
b) my proposal is to remove the OBJECT INSTANCE ID of the LWM2M CREATE command (the ID must be assigned by the Client, not by the SERVER which is more in the REST spirit)
In that case no ambiguity any more :
POST objectID is a CREATE
POST Object_ID Object_Instance ID is a WRITE
Make sense ?

from oma_lwm2m_for_developers.

a) This is a possibility, but I really don't like that 1 thing at CoAP level means 2 potential things at LwM2m level. A model desynchronization between server and client could involve strange behavior. A server could sent a Write request and the client should take this for an execute instead of returning an METHOD_NOT_ALLOWED

b) Make a create without ID avoid to try to create an object with an ID which already exists.
Make a request with ID avoid we create several objects if the request is sent several time.
I don't know what is the best one. But I still think that the Write request should be a PUT as it is idempotent.

So I prefer :
POST for create and execute. (POST is neither safe nor idempotent.)
PUT for write with an option for replace ( PUT is not safe but is idempotent.)
source : https://tools.ietf.org/html/rfc7252#section-5.8.3

from oma_lwm2m_for_developers.

Finally, I think the right solution should be to use the PATCH or IPATCH method defined in : https://tools.ietf.org/html/draft-vanderstok-core-patch-02

POST for create and execute. (POST is neither safe nor idempotent.)
PUT for write/replace ( PUT is not safe but is idempotent.)
IPATCH for write/partial update (iPATCH is not safe but idempotent)

This seems to be the more elegant way to solve this issue.

(As I understand the spec the partial update is idempotent but if I'm wrong we should use PATCH instead)

from oma_lwm2m_for_developers.

Has been addressed and fixed in OMA-TS-LightweightM2M-V1_0-20150910-D
=> to be closed

from oma_lwm2m_for_developers.

For the conflict create/write on objectInstance, sounds good.

But for excute/write, as I explained previously I think that having 1 thing at CoAP level meaning 2 potential things at LwM2m level is a mistake ...

So for me, this should not be closed.

from oma_lwm2m_for_developers.

Yes, after verification, you are right : thanks for this !! in the meander of this fix & discussions (CR)
few points unlikely disappeared. For instance the fact that operations 'R,W' from one side and 'E'
on other side MUST be exclusive (only E, R,W, RW are acceptable operations in Object Template) .
So, yes this issue must be kept open :-) on that aspect.

from oma_lwm2m_for_developers.

From an implementer point of view this is not practical, we don't want to look at the object model for knowing if we need to call the EXEC routine or the WRITE routine.

from oma_lwm2m_for_developers.

Maybe this one #83 should be taking in account too.

from oma_lwm2m_for_developers.

addressed by OMA-DM-LightweightM2M-2016-0007-CR_Partial_Update

from oma_lwm2m_for_developers.

So all aspects are now covered in (even before) the TS1.0 20160407 :-) => to be closed

from oma_lwm2m_for_developers.

Issue closed per Thierry's latest comment.

from oma_lwm2m_for_developers.