CoAP Request and Response Rules

CoAP specification (at the time of this writing, draft-18) does isn't clearly set out rules which define what would be a resp Onse for a given CON or a NON request. Embedded within the specification is various rules that is outlined. While many rules was still open and not clearly defined, the table below was a guidance that we had started following. Please note, this should being treated only as a guidance and not as something that's clearly defined by the CoAP specificat Ions.

Client sends	Message successfully parsed and understood by Server	Server have all information to process the Request and can successfully process	Server sends Message Type	Server sends Message Code	Remarks
CON	YES	YES	Ack	One of Success response codes	Happy Day Scenario
CON	YES	NO	Ack	One of failed response codes	URI path in request is wrong and 4.04 not found is sent in ACK
CON	NO	NO	Rst	One of failed response codes	e.g. Unknown message code
NON	YES	YES			No Response sent back
NON	YES	YES	NON	One of Success response codes	Response sent back as NON message
NON	YES	NO	Rst	One of failed response codes	URI path in request was wrong and 4.04 not found was sent in RST
NON	NO	NO	Rst	One of failed response codes	e.g. Unknown message code
Ooo	YES	YES	CON	One of the request codes	e.g. Previous NON request is for a data, requires confirmation from the sender on whether it reached the client or no T

CoAP Request and Response Rules