PATCH and FETCH Methods for the Constrained Application Protocol (CoAP)

Approval announcement
Draft of message to be sent after approval:

From: The IESG <>
To: "IETF-Announce" <>
Cc:,,,, "The IESG" <>,,, "Jaime Jimenez" <>
Subject: Protocol Action: 'Patch and Fetch Methods for Constrained Application Protocol (CoAP)' to Proposed Standard (draft-ietf-core-etch-04.txt)

The IESG has approved the following document:
- 'Patch and Fetch Methods for Constrained Application Protocol (CoAP)'
  (draft-ietf-core-etch-04.txt) as Proposed Standard

This document is the product of the Constrained RESTful Environments
Working Group.

The IESG contact persons are Alexey Melnikov, Ben Campbell and Alissa

A URL of this Internet Draft is:

Technical Summary

   The existing Constrained Application Protocol (CoAP) methods only
   allow access to a complete resource, not to 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 a CoAP resource.

Working Group Summary

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

Document Quality

   There are no known implementations of the new COAP methods.

   Registration of new COAP media types was requested.


   Jaime Jiménez is the document shepherd. Alexey Melnikov is the responsible Area Director.