Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures
RFC 8610

Document Type RFC - Proposed Standard (June 2019; No errata)
Last updated 2019-06-12
Replaces draft-greevenbosch-appsawg-cbor-cddl
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Stream WG state Submitted to IESG for Publication
Document shepherd Barry Leiba
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IESG IESG state RFC 8610 (Proposed Standard)
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Responsible AD Alexey Melnikov
Send notices to Barry Leiba <barryleiba@computer.org>
IANA IANA review state Version Changed - Review Needed
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Internet Engineering Task Force (IETF)                       H. Birkholz
Request for Comments: 8610                                Fraunhofer SIT
Category: Standards Track                                      C. Vigano
ISSN: 2070-1721                                      Universitaet Bremen
                                                              C. Bormann
                                                 Universitaet Bremen TZI
                                                               June 2019

    Concise Data Definition Language (CDDL): A Notational Convention
         to Express Concise Binary Object Representation (CBOR)
                        and JSON Data Structures

Abstract

   This document proposes a notational convention to express Concise
   Binary Object Representation (CBOR) data structures (RFC 7049).  Its
   main goal is to provide an easy and unambiguous way to express
   structures for protocol messages and data formats that use CBOR or
   JSON.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8610.

Birkholz, et al.             Standards Track                    [Page 1]
RFC 8610                          CDDL                         June 2019

Copyright Notice

   Copyright (c) 2019 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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................4
      1.1. Requirements Notation ......................................5
      1.2. Terminology ................................................5
   2. The Style of Data Structure Specification .......................5
      2.1. Groups and Composition in CDDL .............................7
           2.1.1. Usage ..............................................10
           2.1.2. Syntax .............................................10
      2.2. Types .....................................................11
           2.2.1. Values .............................................11
           2.2.2. Choices ............................................11
           2.2.3. Representation Types ...............................13
           2.2.4. Root Type ..........................................14
   3. Syntax .........................................................15
      3.1. General Conventions .......................................15
      3.2. Occurrence ................................................16
      3.3. Predefined Names for Types ................................17
      3.4. Arrays ....................................................18
      3.5. Maps ......................................................19
           3.5.1. Structs ............................................19
           3.5.2. Tables .............................................22
           3.5.3. Non-deterministic Order ............................23
           3.5.4. Cuts in Maps .......................................24
      3.6. Tags ......................................................25
      3.7. Unwrapping ................................................26
      3.8. Controls ..................................................27
           3.8.1. Control Operator .size .............................27
           3.8.2. Control Operator .bits .............................28
           3.8.3. Control Operator .regexp ...........................29

Birkholz, et al.             Standards Track                    [Page 2]
RFC 8610                          CDDL                         June 2019

           3.8.4. Control Operators .cbor and .cborseq ...............30
           3.8.5. Control Operators .within and .and .................30
           3.8.6. Control Operators .lt, .le, .gt, .ge, .eq,
                  .ne, and .default ..................................31
      3.9. Socket/Plug ...............................................32
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