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Shepherd writeup

## Shepherd Writeup

Full HTML version can be found at:


Document Shepherd: [Jaime Jiménez](
Area Director: [Alexey Melnikov](

The existing Constrained Application Protocol (CoAP) methods only allow access
to a complete resource.  This does not permit applications to access parts of a
resource.  In case of resources with larger or complex data, or in situations
where a resource continuity is required, replacing or requesting the whole
resource is undesirable.  Several applications using CoAP will need to perform
partial resource accesses.

Similar to HTTP, the existing Constrained Application Protocol (CoAP) GET
method only allows the specification of a URI and request parameters in CoAP
options, not the transfer of a request payload detailing the request.  This
leads to some applications to using POST where actually a cacheable,
idempotent, safe request is desired.

Again similar to HTTP, the existing Constrained Application Protocol (CoAP) PUT
method only allows to replace a complete resource.  This also leads
applications to use POST where actually a cacheable, possibly idempotent
request is desired.

This specification adds new CoAP methods, FETCH, to perform the equivalent of a
GET with a request body; and the twin methods PATCH and iPATCH, to modify parts
of an existing CoAP resource.

The document is intended as an Standards Track RFC.

###Review and Consensus

The document has gone through multiple expert reviews and has been discussed on
multiple IETF meetings. Before the last IETF the WGLC was completed.

There are no known implementations available.

###Intellectual Property

Each author has stated that they do not have direct, personal knowledge of any
IPR related to this document. I am not aware of any IPR discussion about this
document on the CoRE WG.

###Other Points
There is a downref to RFC 2616: This is in there because the security
considerations of RFC 7252 reference (the now obsoleted) RFC 2616. The authors
are not aware of someone having done the work to collect the relevant security
considerations from the splinters of RFC 2616 (RFC 7230 and following).


* [x] Does the shepherd stand behind the document and think the document is
ready for publication? * [x] Is the correct RFC type indicated in the title
page header? * [x] Is the abstract both brief and sufficient, and does it stand
alone as a brief summary? * [x] Is the intent of the document accurately and
adequately explained in the introduction? * [x] Have all required formal
reviews (MIB Doctor, Media Type, URI, etc.) been requested and/or completed? *
[x] Has the shepherd performed automated checks -- idnits (see and the Internet-Drafts Checklist), checks of
BNF rules, XML code and schemas, MIB definitions, and so on -- and determined
that the document passes the tests? ` There is no ABNF in this draft` * [x] Has
each author stated that their direct, personal knowledge of any IPR related to
this document has already been disclosed, in conformance with BCPs 78 and 79? *
[x] Have all references within this document been identified as either
normative or informative, and does the shepherd agree with how they have been
classified? `There is a normative reference to [I-D.ietf-core-block] but that
shouldn't be a problem as it is in late stages` * [x] Are all normative
references made to documents that are ready for advancement and are otherwise
in a clear state? * [x] If publication of this document changes the status of
any existing RFCs, are those RFCs listed on the title page header, and are the
changes listed in the abstract and discussed (explained, not just mentioned) in
the introduction? `Does not apply` * [x] If this is a "bis" document, have all
of the errata been considered? `Does not apply`

* **IANA** Considerations:

        * [x] Are the IANA Considerations clear and complete? Remember that
        IANA have to understand unambiguously what's being requested, so they
        can perform the required actions.
`I wonder if adding a link to the CoRE Parameters registry could help, but it
looks OK to me. `
        * [x] Are all protocol extensions that the document makes associated
        with the appropriate reservations in IANA registries? * [x] Are all
        IANA registries referred to by their exact names (check them in to be sure)?
`The two new entries to the content format registry (51 and 52) require expert
review and a request has been SENT to that list.`
        * [x] Have you checked that any registrations made by this document
        correctly follow the policies and procedures for the appropriate
        registries? * [x] For registrations that require expert review
        (policies of Expert Review or Specification Required), have you or the
        working group had any early review done, to make sure the requests are
        ready for last call? * [x] For any new registries that this document
        creates, has the working group actively chosen the allocation
        procedures and policies and discussed the alternatives?
`no new registries`
        * [x]  Have reasonable registry names been chosen (that will not be
        confused with those of other registries), and have the initial contents
        and valid value ranges been clearly specified?