Patch and Fetch Methods for Constrained Application Protocol (CoAP)
draft-ietf-core-etch-02

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Last updated 2016-09-08 (latest revision 2016-08-10)
Replaces draft-vanderstok-core-etch
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core                                                     P. van der Stok
Internet-Draft                                                Consultant
Intended status: Standards Track                              C. Bormann
Expires: February 11, 2017                       Universitaet Bremen TZI
                                                               A. Sehgal
                                                              Consultant
                                                         August 10, 2016

  Patch and Fetch Methods for Constrained Application Protocol (CoAP)
                      draft-ietf-core-etch-02

Abstract

   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.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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van der Stok, et al.    Expires February 11, 2017               [Page 1]
Internet-Draft              CoAP Fetch Patch                 August 2016

   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 11, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  FETCH . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  PATCH and iPATCH  . . . . . . . . . . . . . . . . . . . .   4
     1.3.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     1.4.  Terminology and Acronyms  . . . . . . . . . . . . . . . .   4
   2.  FETCH Method  . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Response Codes  . . . . . . . . . . . . . . . . . . . . .   6
     2.2.  Option Numbers  . . . . . . . . . . . . . . . . . . . . .   6
       2.2.1.  The Content-Format Option . . . . . . . . . . . . . .   6
       2.2.2.  The ETag Option . . . . . . . . . . . . . . . . . . .   6
     2.3.  Working with Observe  . . . . . . . . . . . . . . . . . .   6
     2.4.  Working with Block  . . . . . . . . . . . . . . . . . . .   6
     2.5.  FETCH discussion  . . . . . . . . . . . . . . . . . . . .   7
     2.6.  A Simple Example for FETCH  . . . . . . . . . . . . . . .   7
   3.  PATCH and iPATCH Methods  . . . . . . . . . . . . . . . . . .   8
     3.1.  Simple Examples for PATCH and iPATCH  . . . . . . . . . .   9
     3.2.  Response Codes  . . . . . . . . . . . . . . . . . . . . .  11
     3.3.  Option Numbers  . . . . . . . . . . . . . . . . . . . . .  11
     3.4.  Error Handling  . . . . . . . . . . . . . . . . . . . . .  12
   4.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .  13
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
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