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. Bormann & Romann Expires 22 August 2026 [Page 1] Internet-Draft SDF Supplements February 2026 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 22 August 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. 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 Bormann & Romann Expires 22 August 2026 [Page 2] Internet-Draft SDF Supplements February 2026 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). Bormann & Romann Expires 22 August 2026 [Page 3] Internet-Draft SDF Supplements February 2026 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 } } ] } Bormann & Romann Expires 22 August 2026 [Page 4] Internet-Draft SDF Supplements February 2026 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" } ] } } } Bormann & Romann Expires 22 August 2026 [Page 5] Internet-Draft SDF Supplements February 2026 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 Bormann & Romann Expires 22 August 2026 [Page 6] Internet-Draft SDF Supplements February 2026 { "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 Bormann & Romann Expires 22 August 2026 [Page 7] Internet-Draft SDF Supplements February 2026 { "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 ? defaultNamespace: text amend: [ * amendments ] } amendments = { + global-sdf-pointer => additionalqualities, Bormann & Romann Expires 22 August 2026 [Page 8] Internet-Draft SDF Supplements February 2026 } ; we can't really be much more specific here: additionalqualities = named ; --------------------------------- 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 = { * text => X } ; EXTENSION-POINT is only used in framework syntax EXTENSION-POINT = ( * (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 Bormann & Romann Expires 22 August 2026 [Page 9] Internet-Draft SDF Supplements February 2026 ; 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. Bormann & Romann Expires 22 August 2026 [Page 10] Internet-Draft SDF Supplements February 2026 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. Bormann & Romann Expires 22 August 2026 [Page 11] Internet-Draft SDF Supplements February 2026 { "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. Bormann & Romann Expires 22 August 2026 [Page 12] Internet-Draft SDF Supplements February 2026 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" } } Bormann & Romann Expires 22 August 2026 [Page 13] Internet-Draft SDF Supplements February 2026 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.) Bormann & Romann Expires 22 August 2026 [Page 14] Internet-Draft SDF Supplements February 2026 6. Security Considerations Some wider issues are discussed in [RFC8576]. (Specifics: TBD.) 7. References 7.1. Normative References [BCP14] Best Current Practice 14, . 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, . Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [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, . [RFC6901] Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed., "JavaScript Object Notation (JSON) Pointer", RFC 6901, DOI 10.17487/RFC6901, April 2013, . [RFC7396] Hoffman, P. and J. Snell, "JSON Merge Patch", RFC 7396, DOI 10.17487/RFC7396, October 2014, . [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, . 7.2. Informative References Bormann & Romann Expires 22 August 2026 [Page 15] Internet-Draft SDF Supplements February 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, . [W3C.wot-thing-description11] "Web of Things (WoT) Thing Description 1.1", W3C REC wot- thing-description11, W3C 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 Bormann & Romann Expires 22 August 2026 [Page 16]