



ASDF Working Group                                              E. Ramos
Internet-Draft                                                  Ericsson
Intended status: Standards Track                           13 March 2026
Expires: 14 September 2026


          Semantic Definition Format (SDF) for API translation
                  draft-ramos-asdf-api-translation-02

Abstract

   This document defines an extension to the Semantic Definition Format
   (SDF) that enables API translation between applications and devices.
   The translation enables clarification of complex syntax for a service
   or device to utilize a different API from the one that was first
   designed to use.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   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 14 September 2026.

Copyright Notice

   Copyright (c) 2026 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.




Ramos                   Expires 14 September 2026               [Page 1]

Internet-Draft           SDF for API translation              March 2026


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Discoverable API interfaces . . . . . . . . . . . . . . . . .   4
   3.  Inputting parameters to the API . . . . . . . . . . . . . . .   6
   4.  Methods on the API calls  . . . . . . . . . . . . . . . . . .   9
   5.  Matching API to application logic . . . . . . . . . . . . . .  10
   6.  Ontologies describing APIs  . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
     7.1.  Media Type  . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     10.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   In many cases, a service needed by an application can be provided
   through APIs by several suppliers.  Semantic matching can be used to
   map the needs of the applications and adapt API calls to what the
   service suppliers could provide.  The main purpose of this document
   is to describe methods that enable the translation of one device or
   application API to another equivalent API, utilizing syntax
   understandable by the deploying party.

   An API translator from the original API to the updated one or even
   mapping to a new service would allow an automatic adaptation to the
   target API.  Also, it would enable the possibility to adapt to
   multiple APIs with the same data model, enabling the deployment of
   services from multiple sources.  This feature enables use cases such
   as the usage of the cheapest or most robust service, deployment of
   national services when traveling, and execution of device services
   even from a different ecosystem origin.















Ramos                   Expires 14 September 2026               [Page 2]

Internet-Draft           SDF for API translation              March 2026


   This document provides enabling elements for communication from
   devices or applications belonging to different ecosystems that do not
   share the same semantic modelling.  Utilizing SDF syntax enhanced
   with an API format depiction, it is possible to provide an API
   description that is understandable with the syntax known by the
   device or application, if such semantics are defined in their data
   model.  The final result uses a navigable description of the API's
   functions to provide the necessary information that is required by a
   device application to map external required services, their
   parameters, and results to an application logic using ontologically
   defined objects that can be matched to remote calls in another device
   application, for example.

   The API requires a mapping in applications functions by matching
   syntax in addition to the actual discovery of the API; therefore, the
   importance of the translation to an understandable model.  This
   matching could be enabled by several mechanisms described, and it is
   dynamically adjusted to every new interface faced.  Using SDF in
   conjunction with the given schema allows an automated way to match
   functionality to application intents.

   ┌──────────────────────┐                  ┌──────────────────────┐
   │                      │                  │                      │
   │  Service platform    │                  │  Service platform    │
   │        #1            │                  │        #2            │
   │                      │                  │                      │
   │       ┌──────────────┐                  │       ┌──────────────┐
   │       │ Service API  ┼──┐               │       │ Service API  │
   └───────└─────▲────────┘  │               └───────└─────▲──┬─────┘
                 │           │                             │  │
                 │           │         ┌───────────┐       │  │
                 │           ▼───┐     │ SDF-API   │       │  │
                 └───────────┤   │     │TRANSLATION│       │  │
                             │   ┼─────►  MODEL    ├───────┘  │
                             │   ◄─────┐           ◄──────────┘
                             └───┘     └───────────┘
                            Device

   *Example of a device using the API translation model to access the
   same service in a different platform with a different API*











Ramos                   Expires 14 September 2026               [Page 3]

Internet-Draft           SDF for API translation              March 2026


1.1.  Terminology

   The definitions of [I-D.ietf-asdf-sdf] apply.  The key words "MUST",
   "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
   "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
   interpreted as described in [RFC2119].  As explained in [RFC8174] the
   words apply when, and only when, they appear in all capitals, as
   shown here.

2.  Discoverable API interfaces

   A device or application may expose its capabilities as an API list.
   This could be acquired in real-time by calling a command that
   provides such a list of commands.  For example, the resource “.well-
   known/commands” [RFC8615] could be used as a specific way to request
   all the commands available.  The reply then includes a list of the
   different API supported calls, which would be called in a
   hierarchical way from the root domain that is provided by the device,
   an application, or a mediating platform.  The reply would contain a
   description of the supported API with a semantic definition attached.
   Using the Semantic Definition Format (SDF), a reply for two commands
   may include what is given in the following example:

   {
     "namespace": {
       "name": "Relevant_URL_or_namespace_used_as_semantic_reference_(example)",
       "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns",
       "demo": "https://example.com/iss-demo-setup/#",
     },
     "defaultNamespace": "demo",
     "sdfObject": {
       "target_object": {
         "sdfProperty": {
           "target_property": {
             "description": "possible description of the property",
             "sdfRelation": {
               "FeedType": {
                 "relType": "rdf:type",
                 "target": [
                   "demo:Output"
                 ]
               }
             },
             "contentFormat": "application/typeofcontent-info"
           }
         },
         "sdfAction": {
           "Name_of_the_command_1": {



Ramos                   Expires 14 September 2026               [Page 4]

Internet-Draft           SDF for API translation              March 2026


             "description": "Description of the command and input required",
             "sdfRelation": {
               "FeedType": {
                 "relType": "rdf:type",
                 "target": "demo:command1"
               }
             },
             "sdfInputData": {
               "type": "object",
               "properties": {
                 "input_1_required": {
                   "description": "Description of what element is needed as first input",
                   "sdfRelation": {
                     "FeedType": {
                       "relType": "rdf:type",
                       "target": [
                         "demo:input1"                    ]
                     }
                   },
                   "type": "number",
                   "sdfChoice": {
                     "input_2_required": {
                       "description": "A number needed as an input of the command",
                       "const":"0",
                       "sdfRelation": {
                         "FeedType": {
                           "relType": "rdf:type",
                           "target": [
                             "demo":"input2",
                           ]
                         }
                       }
                     }
                   }
                 }
               }
             },
             "sdfOutputData": {
               "contentFormat": "application/typeofcontent-info"
             }
           },
           "Name_of_the_command_2": {
             "sdfRelation": {
               "FeedType": {
                 "relType": "rdf:type",
                 "target": "demo:command2"
               }
             },



Ramos                   Expires 14 September 2026               [Page 5]

Internet-Draft           SDF for API translation              March 2026


             "sdfInputData": {
               "description": "Description of input required for second command",
               "sdfRelation": {
                 "FeedType": {
                   "relType": "rdf:type",
                   "target": "demo:secondInput"
                 }
               },
               "type": "typeoftheinput",
               "contentFormat": "application/typeofinput-info"
             }
           }
         }
       }
     }
   }

   In this example, one service is defined with a command1, which
   requires an input1 (an object) and input2 (a number).  The other
   service requires a different call (command2), which requires only one
   input (secondInput).

   Further interaction capabilities can be included either in the
   initial response, as shown above in the "sdfAction" block, or could
   be discovered by further requests.  For example, the descriptions of
   the two actions detailed above show if they require input, what the
   details of such input and the output are, and if there is additional
   information related to the nature of the output.  Also, the
   description field could be tailor-made to provide a URI to a
   vocabulary that is understandable by the device or application.  In
   this way, the device or application could make sense of the possible
   options, parameters, and actions that the command provides or
   requires.

3.  Inputting parameters to the API

   Once the available function calls and input parameters required by
   the API have been provisioned to the requester device or application,
   it can make calls to the API when required by its application logic.
   The application would map the “need for a capability” to the concrete
   capability provided by the provider application or device through
   matching the syntax and data model.  The functions are then mapped to
   the calls that the application can handle and has defined syntax.
   The parts of the API that are not understood by the requester device
   are normally ignored.  The mapping semantics from a target device or
   application may be communicated to the application of the requesting
   device using an SDF mapping extension draft [bormann-mapping].  In
   such mapping, the actions and data can be expressed using the data



Ramos                   Expires 14 September 2026               [Page 6]

Internet-Draft           SDF for API translation              March 2026


   model that are understandable by the requester and allows it to
   produce the API call and provide the required data.  The only problem
   with this mapping is that if the API call structure is different, the
   logic required to call the target API might be complicated for
   certain device applications.

   With SDF notation, it is possible to explain the data model but not
   the mapping for a specific API call.  That would require, in some
   cases, mapping of values and, depending on the API definition,
   reshuffling of the parameters or even the URI utilized.

   To tackle those challenges, we introduced a new SDF quality that can
   express URL template patterns from [RFC6570].  The quality
   *"template-href"*, includes the URL or the URL pattern that matches
   the command known by the requester device application.  As explained
   in [RFC6570], the pattern may have variable terms, which are also
   given an SDF definition and relationship so the requested device can
   understand how to map its own data model to what the target API
   requires.  Also, we introduce a value mapper *"template-value"* that
   enables mapping of values to parameters in the target API.  The
   *sdfRelation* [I-D.ietf-asdf-sdf] is used as a vehicle to support the
   mapping between APIs.

   The namespace *"cmd"* MUST be utilized to provide this API mapping
   values.  In this example, we map a command_1 with several inputs to a
   command_2 that utilizes the inputs in a different way.  The schema
   maps semantically the inputs and instructs the system how to make the
   API call based on the previously known API.

     {
    "info":{
       "title": "API mapping of two systems"
     },
     "namespace": {
       "targetSem": "https://example.org/targetSemantics/#",
       "targetDev": "https://example.org/targetDevice",
       "requestDev": "https://example.com/requesterDevice",
       "requestSem": "https://example.com/destinationSemantics/#"
     },
     "defaultNamespace": "requestSem",
     "sdfData": {
       "input_2_required": {
         "type": "number",
         "sdfChoice": {
           "requesterSemantic_1": {
             "const": 1
           },
           "requesterSemantic_2": {



Ramos                   Expires 14 September 2026               [Page 7]

Internet-Draft           SDF for API translation              March 2026


             "const": 2
           }
         },
         "sdfRelation": {
           "FeedType": {
             "relType": "rdf:type",
             "target": [
               "targetDev:#/sdfObject/target_object/sdfAction/Name_of_the_command_1/sdfInputData/input2",
               "requestDev:#/sdfObject/request_object/sdfAction/requester_command/sdfInputData/semanticRequesterInput"
             ]
           }
         }
       }
     },
     "map": {
       "#/sdfObject/request_object/sdfAction/requester_command": {
         "cmd:template-href": "https://example.org/targetDevice/control/Name_of_the_command_1?input1={input_2_required}&input2={input_1}",
         "sdfRelation": {
           "FeedType": {
             "relType": "rdf:type",
             "target": [
               "targetDev:#/sdfObject/target_object/sdfAction/Name_of_the_command_1",
               "requestSem:requester_command"
             ]
           }
         }
       },
       "cmd :template-values": {
         "input2": "#/sdfData/input_1_required",
         "input1": "#/sdfObject/target_object/sdfAction/name_of_command1/sdfInputData/input_1"
       },
       "#/sdfObject/request_object/sdfAction/requester_command_2": {
         "cmd:template-href": "https://example.org/targetDevice/control/Name_of_the_command_2?secondInput={requesterSecondInput}",
         "sdfRelation": {
           "FeedType": {
             "relType": "rdf:type",
             "target": "targetDev:#/sdfObject/target_object/sdfAction/Name_of_the_command_2"
           }
         }
       },
       "cmd:template-values": {
         "secondInput": "#/sdfObject/request_object/sdfAction/requester_command_2/sdfInputData/requesterSecondInput"
       }
     }
   }






Ramos                   Expires 14 September 2026               [Page 8]

Internet-Draft           SDF for API translation              March 2026


4.  Methods on the API calls

   Sometimes, only calling an API is not enough.  For example, in some
   cases, the API call requires additional actions such as submitting a
   payload.  To handle this dimension on the API calls, the *method*
   command has been introduced.  This command SHALL enable the requested
   device to understand how to handle the API call, since in the
   previous example, the API URL has all the information required in the
   call itself.  However, in some cases, the action necessary with the
   API may need to be specified in a manner that the requested device
   can understand.  The keyword *method* is meant to describe how MUST
   be handled the API URL and what to expect of it.  In some other
   examples, the *method* could result in an OBSERVE or another type of
   new action not yet specified, for example, how to address an XR-type
   application.

   An example could be the use of an LWM2M camera [lwm2m-cameraObject].
   To use this model, a payload has to be submitted in the POST method.
   The following example describes such a translation from one camera
   API to the LWM2M model.

   {
       "info": {
         "title": "LwM2M Camera Device to Requester dev. Application API mapping"
       },
       "namespace": {
         "sdm": "https://sdm.wide.ad.jp/sdmo/#/",
         "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns",
         "oma": "https://onedm.org/ecosystem/oma",
         "dev": "http://traffic-light202125.traffic-center.fi/10340/0/",
         "app": "http://owner.mycar.fi/"
       },
       "defaultNamespace": "dev",
       "map": {
         "#/sdfObject/video/sdfAction/playStream": {
           "cmd:template-href": "http://traffic-light202125.traffic-center.fi/10340/0/101",
           "cmd:method":"POST",
           "description": "Starts the recording of the camera",
           "sdfInputData": {
               "type": "number",
               "const":1
            },
           "sdfRelation": {
               "FeedType": {
               "relType": "rdf:type",
                "target": [
                   "dev:#/sdfObject/Camera/sdfAction/Local_Recording_Control",
                   "oma:#/sdfObject/10340/101",



Ramos                   Expires 14 September 2026               [Page 9]

Internet-Draft           SDF for API translation              March 2026


                   "sdm:playStream"              ]
               }
             }
         },
         "#/sdfObject/video/sdfAction/StopStream": {
           "cmd:template-href": "http://traffic-light202125.traffic-center.fi/10340/0/101",
           "cmd:method":"POST",
           "description": "Stops the recording of the camera",
           "sdfInputData": {
                 "type": "number",
                 "const":0
           },
           "sdfRelation": {
             "FeedType": {
             "relType": "rdf:type",
             "target": [
               "dev:#/sdfObject/Camera/sdfAction/Local_Recording_Control",
               "oma:#/sdfObject/10340/101",
               "sdm:stopStream"
             ]
             }
           }
         },
         "#/sdfObject/Camera/sdfProperty/Input-video-stream":{
           "cmd:template-href": "http://traffic-light202125.traffic-center.fi/10340/0/9",
           "sdfRelation": {
             "FeedType": {
               "relType": "rdf:type",
               "target": [
                 "dev:#/sdfObject/Camera/sdfProperty/Recording_Location",
                 "sdm:VideoMedia"
               ]
             }
          }
        }
       }
    }

5.  Matching API to application logic

   Each application has a logic that requires either information from
   the API call or the execution of a service.  With this translation
   tool, the application logic may need to consider the different types
   of APIs that may be present.  For example, if the API requires a
   payload or the info is directly appended to the call.  Also, on the
   way the API produces the output, and how to handle it.





Ramos                   Expires 14 September 2026              [Page 10]

Internet-Draft           SDF for API translation              March 2026


6.  Ontologies describing APIs

   Every application domain has an ontology or vocabulary that indicates
   actions and their parameters.  These actions can be translated to
   APIs but they do not necessarily explain the API itself.  Just the
   result of the API action.

   Some ontologies describing APIs may need to be involved in some
   cases.  Such as W3C Web of Things (WoT) Thing Description (TD)[wot],
   Hydra Core Vocabulary (for hypermedia Web APIs) [hydra] and others
   with less focus in APIs but relevant like OWL S / WSMO (Semantic Web
   Services) [owls], schema.org Actions [schema] and OGC SensorThings
   API [ogc] .

7.  IANA Considerations

   This document has the following actions for IANA.

   Note to RFC Editor: Please replace all occurrences of "{XXXX}" with
   the RFC number of this specification and delete this paragraph.

7.1.  Media Type

   IANA is requested to add the following Media-Type to the "Media Types
   registry [IANA.media-types]. -->

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

              Table 1: A media type for SDF mapping files

8.  Security Considerations

   Some wider issues are discussed in [RFC8576].

9.  Acknowledgements

   Thanks to Ari Keränen for the support in realizing this idea.

10.  References

10.1.  Normative References





Ramos                   Expires 14 September 2026              [Page 11]

Internet-Draft           SDF for API translation              March 2026


   [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>.

   [IANA.media-types]
              IANA, "Media Types",
              <https://www.iana.org/assignments/media-types>.

   [RFC2119]  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/rfc/rfc2119>.

   [RFC8174]  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/rfc/rfc8174>.

10.2.  Informative References

   [bormann-mapping]
              Romann, C. B. and J., "Semantic Definition Format (SDF):
              Mapping files", n.d., <https://datatracker.ietf.org/doc/
              draft-bormann-asdf-sdf-mapping/>.

   [hydra]    "Hydra Core Vocabulary", n.d.,
              <https://www.hydra-cg.com/spec/latest/core/>.

   [lwm2m-cameraObject]
              "Camera - OMAobjectId: 10340 V1.0", n.d.,
              <https://raw.githubusercontent.com/OpenMobileAlliance/
              lwm2m-registry/prod/10340.xml>.

   [ogc]      "OGC SensorThings API Standard", n.d.,
              <https://www.ogc.org/standards/sensorthings/>.

   [owls]     "OWL-S: Semantic Markup for Web Service", n.d.,
              <https://www.w3.org/submissions/OWL-S/>.

   [RFC6570]  Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
              and D. Orchard, "URI Template", RFC 6570,
              DOI 10.17487/RFC6570, March 2012,
              <https://www.rfc-editor.org/rfc/rfc6570>.





Ramos                   Expires 14 September 2026              [Page 12]

Internet-Draft           SDF for API translation              March 2026


   [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>.

   [RFC8615]  Nottingham, M., "Well-Known Uniform Resource Identifiers
              (URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
              <https://www.rfc-editor.org/rfc/rfc8615>.

   [schema]   "Schemas from schema.org", n.d.,
              <https://schema.org/Action>.

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

Author's Address

   Edgar Ramos
   Ericsson
   Hirsalantie 11
   FI- 02420 Jorvas, Kirkkonummi
   Finland
   Email: edgar.ramos@ericsson.com




























Ramos                   Expires 14 September 2026              [Page 13]
