ASDF                                                     C. Bormann, Ed.
Internet-Draft                                    Universität Bremen TZI
Intended status: Standards Track                               J. Romann
Expires: 22 August 2026                               Universität Bremen
                                                        18 February 2026

             Semantic Definition Format (SDF): Supplements
                     draft-ietf-asdf-sdf-mapping-01

Abstract

   The Semantic Definition Format (SDF) is a format for domain experts
   to use in the creation and maintenance of data and interaction models
   that describe Things, i.e., physical objects that are available for
   interaction over a network.  It was created as a common language for
   use in the development of the One Data Model liaison organization
   (OneDM) models.  Tools convert this format to database formats and
   other serializations as needed.

   An SDF specification often needs to be augmented by additional
   information that is specific to its use in a particular ecosystem or
   application.  SDF Supplements provide a mechanism to represent this
   augmentation.

About This Document

   This note is to be removed before publishing as an RFC.

   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-ietf-asdf-sdf-mapping/.

   Discussion of this document takes place on the A Semantic Definition
   Format for Data and Interactions of Things (asdf) Working Group
   mailing list (mailto:asdf@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/asdf/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/asdf/.

   Source for this draft and an issue tracker can be found at
   https://github.com/cabo/sdf-mapping.

Status of This Memo

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

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Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology and Conventions . . . . . . . . . . . . . . .   3
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Example Model 1 (ecosystem: IPSO/OMA) . . . . . . . . . .   4
     2.2.  Example Model 2 (ecosystem: W3C WoT)  . . . . . . . . . .   5
   3.  Formal Syntax of SDF Supplements  . . . . . . . . . . . . . .   8
   4.  Augmentation Mechanism  . . . . . . . . . . . . . . . . . . .  10
     4.1.  Logging Augmentation  . . . . . . . . . . . . . . . . . .  13
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     5.1.  Media Type  . . . . . . . . . . . . . . . . . . . . . . .  14
     5.2.  Registries  . . . . . . . . . . . . . . . . . . . . . . .  14
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   List of Figures . . . . . . . . . . . . . . . . . . . . . . . . .  16
   List of Tables  . . . . . . . . . . . . . . . . . . . . . . . . .  16
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

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1.  Introduction

   The Semantic Definition Format (SDF) is a format for domain experts
   to use in the creation and maintenance of data and interaction models
   that describe Things, i.e., physical objects that are available for
   interaction over a network.  It was created as a common language for
   use in the development of the One Data Model liaison organization
   (OneDM) models.  Tools convert this format to database formats and
   other serializations as needed.

   An SDF specification often needs to be augmented by additional
   information that is specific to its use in a particular ecosystem or
   application.  SDF Supplements provide a mechanism to represent this
   augmentation.

   // In this revision, we have renamed the map quality to amend since
   // the underlying data structure changed from an object to an array.
   // For this reason, we also change the term "Mapping File" to
   // "Supplement" to also reflect the fact that the file does not
   // actually contain a _map_ for describing the augmentation anymore.

1.1.  Terminology and Conventions

   The definitions of [I-D.ietf-asdf-sdf] apply.

   The term "byte" is used in its now-customary sense as a synonym for
   "octet".

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [BCP14] (RFC2119) (RFC8174) when, and only when, they appear in all
   capitals, as shown here.

2.  Overview

   An SDF Supplement provides augmentation information for one or more
   SDF models.  Its main contents are an array of patches that are
   applied using SDF name references (Section 4.3 of
   [I-D.ietf-asdf-sdf]) as the respective target.

   When processing the Supplement together with one or more SDF models,
   the qualities from the array elements are added to the SDF model at
   the referenced name, as in a merge-patch operation [RFC7396].  Note
   that this is somewhat similar to the way sdfRef (Section 4.4 of
   [I-D.ietf-asdf-sdf]) works, but in a Supplement the arrows point in
   the inverse direction (from the augmenter to the augmented).

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   The order of the application of patches is that of the elements
   within the array (which is deterministic in contrast to the order of
   entries of an object).

2.1.  Example Model 1 (ecosystem: IPSO/OMA)

   An example for an SDF Supplement is given in Figure 1.  This
   Supplement is meant to attach to an SDF specification published by
   OneDM, and to add qualities relevant to the IPSO/OMA ecosystem.
   // Note that this example uses namespaces to identify elements of
   // the referenced specification(s), but has un-namespaced quality
   // names.  These two kinds of namespaces are unrelated in SDF, and a
   // more robust example may need to make use of Quality Name Prefixes
   // as defined in Section 2.3.3-3 of [I-D.ietf-asdf-sdf] (independent
   // of a potential feature to add namespace references to definitions
   // that are not intended to go into the default namespace — these are
   // SDF definition namespaces and not quality namespaces, which are
   // one meta-level higher).

   *  Start of a Supplement for certain OneDM playground models:

   {
     "info": {
       "title": "IPSO ID mapping"
     },
     "namespace": {
       "onedm": "https://onedm.org/models"
     },
     "defaultNamespace": "onedm",
     "amend": [
       {
         "#/sdfObject/Digital_Input": {
           "id": 3200
         }
       },
       {
         "#/sdfObject/Digital_Input/sdfProperty/Digital_Input_State": {
           "id": 5500
         }
       },
       {
         "#/sdfObject/Digital_Input/sdfProperty/Digital_Input_Counter": {
           "id": 5501
         }
       }
     ]
   }

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              Figure 1: A simple example of an SDF Supplement

2.2.  Example Model 2 (ecosystem: W3C WoT)

   This example shows a translation of a hypothetical W3C WoT Thing
   Model (as defined in Section 10 of [W3C.wot-thing-description11])
   into an SDF model plus a Supplement to catch Thing Model attributes
   that don't currently have SDF qualities defined (namely, titles and
   descriptions members used for internationalization).

   A second Supplement is more experimental in that it captures
   information that is actually instance-specific, in this case a forms
   member that binds the status property to an instance-specific CoAP
   resource.
   // Namespaces are all wrong in this example.

   The form really should be part of the class level; defining the
   entire form instead of just the link in the instance information is a
   symptom of not yet getting the class/instance boundary right.

   *  The input: WoT Thing Model

   {
       "@context": "https://www.w3.org/2022/wot/td/v1.1",
       "@type" : "tm:ThingModel",
       "title": "Lamp Thing Model",
       "titles": {
         "en": "Lamp Thing Model",
         "de": "Thing Model für eine Lampe"
       },
       "properties": {
           "status": {
               "description": "Current status of the lamp",
               "descriptions": {
                 "en": "Current status of the lamp",
                 "de": "Aktueller Status der Lampe"
               },
               "type": "string",
               "readOnly": true,
               "forms": [
                 {
                   "href": "coap://example.org/status"
                 }
               ]
           }
       }
   }

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                      Figure 2: Input: WoT Thing Model

   *  The output: SDF model

   {
     "info": {
       "title": "Lamp Thing Model"
     },
     "namespace": {
       "wot": "http://www.w3.org/ns/td"
     },
     "defaultNamespace": "wot",
     "sdfObject": {
       "LampThingModel": {
         "label": "Lamp Thing Model",
         "sdfProperty": {
           "status": {
             "description": "Current status of the lamp",
             "writable": false,
             "type": "string"
           }
         }
       }
     }
   }

                       Figure 3: Output 1: SDF Model

   *  The other output: SDF Supplement for class information

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   {
     "info": {
       "title": "Lamp Thing Model: WoT TM mapping"
     },
     "namespace": {
       "wot": "http://www.w3.org/ns/td"
     },
     "defaultNamespace": "wot",
     "amend": [
       {
         "#/sdfObject/LampThingModel": {
           "titles": {
             "en": "Lamp Thing Model",
             "de": "Thing Model für eine Lampe"
           }
         }
       },
       {
         "#/sdfObject/LampThingModel/sdfProperty/status": {
           "descriptions": {
             "en": "Current status of the lamp",
             "de": "Aktueller Status der Lampe"
           }
         }
       }
     ]
   }

                     Figure 4: Output 2: SDF Supplement

   *  A third output: SDF Supplement for Protocol Bindings

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   {
     "info": {
       "title": "Lamp Thing Model: WoT TM Protocol Binding"
     },
     "namespace": {
       "wot": "http://www.w3.org/ns/td"
     },
     "defaultNamespace": "wot",
     "amend": [
       {
         "#/sdfObject/LampThingModel/sdfProperty/status": {
           "descriptions": [
             {
               "href": "coap://example.org/status"
             }
           ]
         }
       }
     ]
   }

          Figure 5: Output 3: SDF Supplement for Protocol Bindings

3.  Formal Syntax of SDF Supplements

   An SDF Supplement has three optional components that are taken
   unchanged from SDF: The info block, the namespace declaration, and
   the default namespace.  The mandatory fourth component, the amend
   block, contains the list of amendments that are supposed to be
   applied to the target model, using an SDF name reference (usually a
   namespace and a JSON pointer) as the target to which a specified
   quality is applied to.

   Figure 6 describes the syntax of SDF Supplements using CDDL
   [RFC8610].

   start = sdf-mapping

   sdf-mapping = {
    ; info will be required in most process policies
    ? info: sdfinfo
    ? namespace: named<text>
    ? defaultNamespace: text
    amend: [ * amendments ]
   }

   amendments = {
     + global-sdf-pointer => additionalqualities,

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   }

   ; we can't really be much more specific here:
   additionalqualities = named<any>

   ; --------------------------------- import from SDF-base:

   sdfinfo = {
    ? title: text
    ? description: text
    ? version: text
    ? copyright: text
    ? license: text
    ? modified: modified-date-time
    ? features: [
                  * (any .feature "feature-name") ; EXTENSION-POINT
                ]
    optional-comment
    EXTENSION-POINT<"info-ext">
   }

   ; Shortcut for a map that gives names to instances of X
   ; (has keys of type text and values of type X)
   named<X> = { * text => X }

   ; EXTENSION-POINT is only used in framework syntax
   EXTENSION-POINT<f> = ( * (quality-name .feature f) => any )
   quality-name = text .regexp "([a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*"

   ; rough CURIE or JSON Pointer syntax:
   global-sdf-pointer = text .regexp ".*[:#].*"

   optional-comment = (
    ? $comment: text       ; source code comments only, no semantics
   )

   modified-date-time = text .abnf modified-dt-abnf
   modified-dt-abnf = "modified-dt" .det rfc3339z

   ; RFC 3339 sans time-numoffset, slightly condensed
   rfc3339z = '
      date-fullyear   = 4DIGIT
      date-month      = 2DIGIT  ; 01-12
      date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on
                                ; month/year
      time-hour       = 2DIGIT  ; 00-23
      time-minute     = 2DIGIT  ; 00-59
      time-second     = 2DIGIT  ; 00-58, 00-59, 00-60 based on leap sec

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                                ; rules
      time-secfrac    = "." 1*DIGIT
      DIGIT           =  %x30-39 ; 0-9

      partial-time    = time-hour ":" time-minute ":" time-second
                        [time-secfrac]
      full-date       = date-fullyear "-" date-month "-" date-mday

      modified-dt     = full-date ["T" partial-time "Z"]
   '

                Figure 6: CDDL definition of SDF Supplements

   The JSON pointer that is used a the target can point to a JSON map in
   the SDF model to be augmented by adding or replacing map entries.  If
   necessary, the JSON map is created at the position indicated with the
   contents of the patch
   // (add examples).  Alternatively, the JSON pointer can point to an
   array (also possibly created if not existing before) and add an
   element to that array by using the "-" syntax introduced in the
   penultimate paragraph of Section 4 of [RFC6901].

4.  Augmentation Mechanism

   An SDF model and a compatible Supplement can be combined to create an
   _augmented_ SDF model.  (This process can be repeated with multiple
   Supplements by using the outcome of one augmentation as the input of
   the next one.)  As augmentation is not equal to instantiation,
   augmented SDF models are still abstract in nature, but are enriched
   with ecosystem-specific information.

      |  Note that it might be necessary to specify an augmentation
      |  mechanism for instance descriptions as well at a later point in
      |  time, once it has been decided what the instance description
      |  format might look like and whether such a format is needed.

   The augmentation mechanism is related to the resolution mechanism
   defined in Section 4.4 of [I-D.ietf-asdf-sdf], but fundamentally
   different:

   Instead of a model file reaching out to other model files and
   integrating aspects into itself via sdfRef (_pull_ approach), the
   Supplement _pushes_ information into a new copy of a specific given
   SDF model.  The original SDF model does not need to know which
   Supplements it will be used with and can be used with several such
   Supplements independently of each other.

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   An augmented SDF model is produced from two inputs: An SDF model and
   a compatible Supplement, i.e. every JSON pointer key within elements
   of the amend array points to a location that already exists within
   the SDF model or has been created by a previous augmentation step.
   To perform the augmentation, a processor needs to create a copy of
   the original SDF model.  It then iterates over all entries within the
   Supplement's amend array elements.  During each iteration, the
   processor first obtains a reference to the target referred to by the
   JSON pointer in the respective key.  This reference is then used as
   the Target argument of the JSON Merge Patch algorithm [RFC7396] and
   the entry's value as the Patch argument; the target is replaced with
   the result of the merge-patch.

   Once the iteration has finished, the processor returns the resulting
   augmented SDF model.  Should the resolution of a JSON pointer or an
   application of the JSON Merge Patch algorithm fail, an error is
   thrown instead.

   An example for an augmented SDF model can be seen in Figure 7.  This
   is the result of applying the WoT-specific Supplement from Figure 4
   to the SDF model shown in Figure 3.  This augmented SDF model is one
   step away from being converted to a WoT Thing Model or Thing
   Description, which requires some information that cannot be provided
   in an SDF model that is limited to the vocabulary defined in the SDF
   base specification.

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   {
     "info": {
       "title": "Lamp Thing Model"
     },
     "namespace": {
       "wot": "http://www.w3.org/ns/td"
     },
     "defaultNamespace": "wot",
     "sdfObject": {
       "LampThingModel": {
         "label": "Lamp Thing Model",
         "titles": {
           "en": "Lamp Thing Model",
           "de": "Thing Model für eine Lampe"
         },
         "sdfProperty": {
           "status": {
             "description": "Current status of the lamp",
             "descriptions": {
               "en": "Current status of the lamp",
               "de": "Aktueller Status der Lampe"
             },
             "writable": false,
             "type": "string"
           }
         }
       }
     }
   }

      Figure 7: An SDF model that has been augmented with WoT-specific
                                vocabulary.

      |  Since the pair of an SDF model and a Supplement is equivalent
      |  in semantics to the augmented model created from the two, there
      |  is no fundamental difference between specifying aspects in the
      |  SDF model or leaving them in a Supplement.  Also, parts of an
      |  ecosystem-specific vocabulary may in fact be mappable to the
      |  SDF base vocabulary.  Therefore, developing the mapping between
      |  SDF and an ecosystem requires careful consideration which of
      |  the features should be available to other ecosystems and
      |  therefore should best be part of the common SDF model, and
      |  which are best handled in a Supplement specific to the
      |  ecosystem.

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4.1.  Logging Augmentation

   Since an augmented model is not fundamentally different from any
   other SDF model, it may be necessary to trace the provenance of the
   information that flowed into it, e.g., in the info block.  For this
   purpose, a new quality called augmentationLog is introduced that
   contains an array of URIs pointing to the Supplements that have been
   used to augment the original SDF file (which can also be indicated
   via the originalSdfModel quality).  These additional qualities allow
   for reproducing the augmentation process.

   For logging while performing an augmentation, the processor has to
   perform the following steps:

   1.  If the info block is not present in the model that is being
       augmented, the processor creates it.

   2.  If the info block does not contain an augmentationLog quality,
       the processor performs the following steps:

       1.  If the originalSdfModel quality is not present in the info
           block, the processor adds it with a URI that can be used to
           access the SDF model that is currently being augmented as its
           value.

       2.  The processor creates the augmentationLog quality with an
           array containing URIs that can be used to access the current
           Supplement as its sole item.

   3.  Otherwise, if augmentationLog does not contain an array, stop and
       throw an error.

   4.  Otherwise, the processor adds a URI that can be used to access
       the current Supplement to the array of the augmentationLog
       quality.

   {
     "info": {
       "title": "Augmented SDF model with augmentation log.",
       "augmentationLog": [
         "https://example.org/sdf-mapping-file-1",
         "https://example.org/sdf-mapping-file-2"
       ],
       "originalSdfModel": "https://example.org/original-sdf-model"
     }
   }

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       Figure 8: An augmented SDF model with an augmentation log and
               information regarding the original SDF model.

5.  IANA Considerations

5.1.  Media Type

   IANA is requested to add the following Media-Type to the "Media
   Types" registry.

   +==================+=================================+=============+
   | Name             | Template                        | Reference   |
   +==================+=================================+=============+
   | sdf-mapping+json | application/sdf-supplement+json | RFC XXXX,   |
   |                  |                                 | Section 5.1 |
   +------------------+---------------------------------+-------------+

                Table 1: A media type for SDF Supplements

   // RFC Editor: please replace RFC XXXX with this RFC number and
   // remove this note.

   Type name:  application
   Subtype name:  sdf-mapping+json
   Required parameters:  none
   Optional parameters:  none
   Encoding considerations:  binary (JSON is UTF-8-encoded text)
   Security considerations:  Section 6 of RFC XXXX
   Interoperability considerations:  none
   Published specification:  Section 5.1 of RFC XXXX
   Applications that use this media type:  Tools for data and
      interaction modeling that describes Things, i.e., physical objects
      that are available for interaction over a network
   Fragment identifier considerations:  A JSON Pointer fragment
      identifier may be used, as defined in Section 6 of [RFC6901].
   Person & email address to contact for further information:  ASDF WG
      mailing list (asdf@ietf.org), or IETF Applications and Real-Time
      Area (art@ietf.org)
   Intended usage:  COMMON
   Restrictions on usage:  none
   Author/Change controller:  IETF
   Provisional registration:  no

5.2.  Registries

   (TBD: After any future additions, check if we need any.)

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6.  Security Considerations

   Some wider issues are discussed in [RFC8576].

   (Specifics: TBD.)

7.  References

7.1.  Normative References

   [BCP14]    Best Current Practice 14,
              <https://www.rfc-editor.org/info/bcp14>.
              At the time of writing, this BCP comprises the following:

              Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

              Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [I-D.ietf-asdf-sdf]
              Koster, M., Bormann, C., and A. Keränen, "Semantic
              Definition Format (SDF) for Data and Interactions of
              Things", Work in Progress, Internet-Draft, draft-ietf-
              asdf-sdf-25, 13 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-asdf-
              sdf-25>.

   [RFC6901]  Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed.,
              "JavaScript Object Notation (JSON) Pointer", RFC 6901,
              DOI 10.17487/RFC6901, April 2013,
              <https://www.rfc-editor.org/rfc/rfc6901>.

   [RFC7396]  Hoffman, P. and J. Snell, "JSON Merge Patch", RFC 7396,
              DOI 10.17487/RFC7396, October 2014,
              <https://www.rfc-editor.org/rfc/rfc7396>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.

7.2.  Informative References

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   [RFC8576]  Garcia-Morchon, O., Kumar, S., and M. Sethi, "Internet of
              Things (IoT) Security: State of the Art and Challenges",
              RFC 8576, DOI 10.17487/RFC8576, April 2019,
              <https://www.rfc-editor.org/rfc/rfc8576>.

   [W3C.wot-thing-description11]
              "Web of Things (WoT) Thing Description 1.1", W3C REC wot-
              thing-description11, W3C wot-thing-description11,
              <https://www.w3.org/TR/wot-thing-description11/>.

List of Figures

   Figure 1:  A simple example of an SDF Supplement
   Figure 2:  Input: WoT Thing Model
   Figure 3:  Output 1: SDF Model
   Figure 4:  Output 2: SDF Supplement
   Figure 5:  Output 3: SDF Supplement for Protocol Bindings
   Figure 6:  CDDL definition of SDF Supplements
   Figure 7:  An SDF model that has been augmented with WoT-specific
              vocabulary.

List of Tables

   Table 1:   A media type for SDF Supplements

Acknowledgements

   This draft is based on discussions in the Thing-to-Thing Research
   Group (T2TRG) and the SDF working group.  Input for Section 2.1 was
   provided by Ari Keränen.

Authors' Addresses

   Carsten Bormann (editor)
   Universität Bremen TZI
   Postfach 330440
   D-28359 Bremen
   Germany
   Phone: +49-421-218-63921
   Email: cabo@tzi.org

   Jan Romann
   Universität Bremen
   Germany
   Email: jan.romann@uni-bremen.de

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