Internet DRAFT - draft-ietf-asdf-sdf
draft-ietf-asdf-sdf
ASDF M. Koster, Ed.
Internet-Draft KTC
Intended status: Standards Track C. Bormann, Ed.
Expires: 1 September 2024 Universität Bremen TZI
A. Keränen
Ericsson
29 February 2024
Semantic Definition Format (SDF) for Data and Interactions of Things
draft-ietf-asdf-sdf-18
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. An SDF specification describes
definitions of SDF Objects/SDF Things and their associated
interactions (Events, Actions, Properties), as well as the Data types
for the information exchanged in those interactions. Tools convert
this format to database formats and other serializations as needed.
// The present revision (-18) adds security considerations, a few
// editorial cleanups, discusses JSON pointer encodings, and adds
// sockets to the CDDL for easier future extension.
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/.
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/ietf-wg-asdf/SDF.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Koster, et al. Expires 1 September 2024 [Page 1]
Internet-Draft SDF (Semantic Definition Format) February 2024
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 1 September 2024.
Copyright Notice
Copyright (c) 2024 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 . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology and Conventions . . . . . . . . . . . . . . . 4
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Example Definition . . . . . . . . . . . . . . . . . . . 7
2.2. Elements of an SDF model . . . . . . . . . . . . . . . . 9
2.2.1. sdfObject . . . . . . . . . . . . . . . . . . . . . . 10
2.2.2. sdfProperty . . . . . . . . . . . . . . . . . . . . . 11
2.2.3. sdfAction . . . . . . . . . . . . . . . . . . . . . . 12
2.2.4. sdfEvent . . . . . . . . . . . . . . . . . . . . . . 12
2.2.5. sdfData . . . . . . . . . . . . . . . . . . . . . . . 13
2.2.6. sdfThing . . . . . . . . . . . . . . . . . . . . . . 13
2.3. Member names: Given Names and Quality Names . . . . . . . 14
2.3.1. Given Names and Quality Names . . . . . . . . . . . . 14
2.3.2. Hierarchical Names . . . . . . . . . . . . . . . . . 14
2.3.3. Extensibility of Given Names and Quality Names . . . 15
3. SDF structure . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1. Information block . . . . . . . . . . . . . . . . . . . . 16
3.2. Namespaces block . . . . . . . . . . . . . . . . . . . . 18
3.3. Definitions block . . . . . . . . . . . . . . . . . . . . 19
3.4. Top-level Affordances and sdfData . . . . . . . . . . . . 21
Koster, et al. Expires 1 September 2024 [Page 2]
Internet-Draft SDF (Semantic Definition Format) February 2024
4. Names and namespaces . . . . . . . . . . . . . . . . . . . . 21
4.1. Structure . . . . . . . . . . . . . . . . . . . . . . . . 21
4.2. Contributing global names . . . . . . . . . . . . . . . . 21
4.3. Referencing global names . . . . . . . . . . . . . . . . 22
4.4. sdfRef . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.4.1. Resolved models . . . . . . . . . . . . . . . . . . . 25
4.5. sdfRequired . . . . . . . . . . . . . . . . . . . . . . . 26
4.6. Common Qualities . . . . . . . . . . . . . . . . . . . . 29
4.7. Data Qualities . . . . . . . . . . . . . . . . . . . . . 29
4.7.1. sdfType . . . . . . . . . . . . . . . . . . . . . . . 31
4.7.2. sdfChoice . . . . . . . . . . . . . . . . . . . . . . 32
5. Keywords for definition groups . . . . . . . . . . . . . . . 34
5.1. sdfObject . . . . . . . . . . . . . . . . . . . . . . . . 34
5.2. sdfProperty . . . . . . . . . . . . . . . . . . . . . . . 35
5.3. sdfAction . . . . . . . . . . . . . . . . . . . . . . . . 36
5.4. sdfEvent . . . . . . . . . . . . . . . . . . . . . . . . 37
5.5. sdfData . . . . . . . . . . . . . . . . . . . . . . . . . 37
6. High Level Composition . . . . . . . . . . . . . . . . . . . 38
6.1. Paths in the model namespaces . . . . . . . . . . . . . . 38
6.2. Modular Composition . . . . . . . . . . . . . . . . . . . 38
6.2.1. Use of the "sdfRef" keyword to re-use a definition . 39
6.3. sdfThing . . . . . . . . . . . . . . . . . . . . . . . . 40
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41
7.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 41
7.2. Content-Format . . . . . . . . . . . . . . . . . . . . . 42
7.3. IETF URN Sub-namespace for Unit Names
(urn:ietf:params:unit) . . . . . . . . . . . . . . . . . 43
7.4. Registries . . . . . . . . . . . . . . . . . . . . . . . 43
7.4.1. Quality Name Prefixes . . . . . . . . . . . . . . . . 43
7.4.2. sdfType Values . . . . . . . . . . . . . . . . . . . 44
8. Security Considerations . . . . . . . . . . . . . . . . . . . 45
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 46
9.1. Normative References . . . . . . . . . . . . . . . . . . 47
9.2. Informative References . . . . . . . . . . . . . . . . . 49
Appendix A. Formal Syntax of SDF . . . . . . . . . . . . . . . . 51
Appendix B. json-schema.org Rendition of SDF Syntax . . . . . . 56
Appendix C. Data Qualities inspired by json-schema.org . . . . . 98
C.1. type "number", type "integer" . . . . . . . . . . . . . . 98
C.2. type "string" . . . . . . . . . . . . . . . . . . . . . . 98
C.3. type "boolean" . . . . . . . . . . . . . . . . . . . . . 100
C.4. type "array" . . . . . . . . . . . . . . . . . . . . . . 100
C.5. type "object" . . . . . . . . . . . . . . . . . . . . . . 100
C.6. Implementation notes . . . . . . . . . . . . . . . . . . 100
Appendix D. Composition Examples . . . . . . . . . . . . . . . . 101
D.1. Outlet Strip Example . . . . . . . . . . . . . . . . . . 101
D.2. Refrigerator-Freezer Example . . . . . . . . . . . . . . 101
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 102
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Koster, et al. Expires 1 September 2024 [Page 3]
Internet-Draft SDF (Semantic Definition Format) February 2024
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 103
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. An SDF specification describes
definitions of SDF Objects/SDF Things and their associated
interactions (Events, Actions, Properties), as well as the Data types
for the information exchanged in those interactions. Tools convert
this format to database formats and other serializations as needed.
// The present revision (-18) adds security considerations, a few
// editorial cleanups, discusses JSON pointer encodings, and adds
// sockets to the CDDL for easier future extension.
SDF is designed to be an extensible format. The present document
constitutes the base specification for SDF; we speak of "base SDF"
for short. In addition, SDF extensions can be defined, some of which
may make use of extension points specifically defined for this in
base SDF. One area for such extensions would be refinements of SDF's
abstract interaction models into protocol bindings for specific
ecosystems (e.g., [I-D.bormann-asdf-sdf-mapping]). For other
extensions, it may be necessary to indicate in the SDF document that
a specific extension is in effect; see Section 3.1 for details of the
features quality that can be used for such indications. With
extension points and feature indications available, base SDF does not
define a "version" concept for the SDF format itself (as opposed to
version indications within SDF documents indicating their own
evolution, see Section 3.1).
1.1. Terminology and Conventions
Thing: A physical item that is also available for interaction over a
network.
Grouping: An sdfThing or sdfObject, i.e., (directly or indirectly) a
combination of Affordances.
sdfThing: A grouping of Groupings as well as potentially Affordance
declarations (Property, Action, and Event declarations).
Affordance: An element of an interface offered for interaction, for
Koster, et al. Expires 1 September 2024 [Page 4]
Internet-Draft SDF (Semantic Definition Format) February 2024
which information is available (directly or indirectly) that
indicates how it can or should be used. The term is used here for
the digital (network-directed) interfaces of a Thing only; it
might also have physical affordances such as buttons, dials, and
displays.
Quality: A metadata item in a definition or declaration which says
something about that definition or declaration. A quality is
represented in SDF as an entry in a JSON map (JSON object) that
serves as a definition or declaration.
Entry: A key-value pair in a map. (In JSON maps, sometimes also
called "member".)
Block: One or more entries in a JSON map that is part of an SDF
specification; these entries together serve a specific function.
Group: An entry in the main JSON map representing the SDF document,
and in certain nested definitions, that has a Class Name Keyword
as its key and a map of named definition entries (Definition
Group) as a value.
Class Name Keyword: One of sdfThing, sdfObject, sdfProperty,
sdfAction, sdfEvent, or sdfData; the Classes for these type
keywords are capitalized and prefixed with sdf.
Class: Abstract term for the information that is contained in groups
identified by a Class Name Keyword.
Property: An affordance that can potentially be used to read, write,
and/or observe state (current/stored information) on an sdfObject.
(Note that Entries are often called properties in other
environments; in this document, the term Property is specifically
reserved for affordances, even if the map key "properties" might
be imported from a data definition language with the other
semantics.)
Action: An affordance that can potentially be used to perform a
named operation on an sdfObject.
Event: An affordance that can potentially be used to obtain
information about what happened to an sdfObject.
Object, sdfObject: A grouping containing only Affordance
declarations (Property, Action, and Event declarations); the main
"atom" of reusable semantics for model construction. sdfObjects
are similar to sdfThings but do not allow nesting, i.e., they
cannot contain other Groupings (sdfObjects or sdfThings). (Note
Koster, et al. Expires 1 September 2024 [Page 5]
Internet-Draft SDF (Semantic Definition Format) February 2024
that JSON maps are often called JSON objects due to JSON's
JavaScript heritage; in the context of SDF, the term Object as the
colloquial shorthand for sdfObject, is specifically reserved for
the above grouping, even if the type name "object" is imported
from a data definition language with the other semantics.)
Element: A part or an aspect of something abstract; used here in its
usual English definition. (Occasionally, also used specifically
for the elements of JSON arrays.)
Definition: An entry in a Definition Group; the entry creates a new
semantic term for use in SDF models and associates it with a set
of qualities. Unless it is also a Declaration, a definition just
defines a term, it does not create a component item within the
enclosing definition.
Declaration: A definition within an enclosing definition, intended
to create a component item within that enclosing definition.
Every declaration can also be used as a definition for reference
in a different place.
SDF Document: Container for SDF Definitions, together with data
about the SDF Document itself (information block). Represented as
a JSON text representing a single JSON map, which is built from
nested maps.
SDF Model: Definitions and declarations that model the digital
interaction opportunities offered by one or more kinds of Things,
represented by sdfObjects and sdfThings. An SDF Model can be
fully contained in a single SDF Document, or it can be built from
an SDF Document that references definitions and declarations from
additional SDF documents.
Protocol Binding: A companion document to an SDF Model that defines
how to map the abstract concepts in the model into the protocols
in use in a specific ecosystem. Might supply URL components,
numeric IDs, and similar details. Protocol Bindings are one case
of an Augmentation Mechanism.
Augmentation Mechanism: A companion document to a base SDF Model
that provides additional information ("augments" the base
specification), possibly for use in a specific ecosystem or with a
specific protocol ("Protocol Binding"). No specific Augmentation
Mechanisms are defined in base SDF. A simple mechanism for such
augmentations has been discussed as a "mapping file"
[I-D.bormann-asdf-sdf-mapping].
Koster, et al. Expires 1 September 2024 [Page 6]
Internet-Draft SDF (Semantic Definition Format) February 2024
The term "byte" is used in its now-customary sense as a synonym for
"octet".
Conventions:
* The singular form is chosen as the preferred one for the keywords
defined here.
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
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Overview
2.1. Example Definition
We start with an example for the SDF definition of a simple sdfObject
called "Switch" (Figure 1).
Koster, et al. Expires 1 September 2024 [Page 7]
Internet-Draft SDF (Semantic Definition Format) February 2024
{
"info": {
"title": "Example document for SDF (Semantic Definition Format)",
"version": "2019-04-24",
"copyright": "Copyright 2019 Example Corp. All rights reserved.",
"license": "https://example.com/license"
},
"namespace": {
"cap": "https://example.com/capability/cap"
},
"defaultNamespace": "cap",
"sdfObject": {
"Switch": {
"sdfProperty": {
"value": {
"description":
"The state of the switch; false for off and true for on.",
"type": "boolean"
}
},
"sdfAction": {
"on": {
"description":
"Turn the switch on; equivalent to setting value to true."
},
"off": {
"description":
"Turn the switch off; equivalent to setting value to false."
},
"toggle": {
"description":
"Toggle the switch; equivalent to setting value to its complement."
}
}
}
}
}
Figure 1: A simple example of an SDF document
Koster, et al. Expires 1 September 2024 [Page 8]
Internet-Draft SDF (Semantic Definition Format) February 2024
This is a model of a switch. The state value declared in the
sdfProperty group, represented by a Boolean, will be true for "on"
and will be false for "off". The actions on or off declared in the
sdfAction group are redundant with setting the value and are in the
example to illustrate that there are often different ways of
achieving the same effect. The action toggle will invert the value
of the sdfProperty value, so that 2-way switches can be created;
having such action will avoid the need for first retrieving the
current value and then applying/setting the inverted value.
The sdfObject group lists the affordances of Things modeled by this
sdfObject. The sdfProperty group lists the property affordances
described by the model; these represent various perspectives on the
state of the sdfObject. Properties can have additional qualities to
describe the state more precisely. Properties can be annotated to be
read, write or read/write; how this is actually done by the
underlying transfer protocols is not described in the SDF model but
left to companion protocol bindings. Properties are often used with
RESTful paradigms [I-D.irtf-t2trg-rest-iot], describing state. The
sdfAction group is the mechanism to describe other interactions in
terms of their names, input, and output data (no data are used in the
example), as in a POST method in REST or in a remote procedure call.
The example toggle is an Action that changes the state based on the
current state of the Property named value. (The third type of
affordance is Events, which are not described in this example.)
In the JSON representation, note how (with the exception of the info
group) maps that have keys taken from the SDF vocabulary (info,
namespace, sdfObject) alternate in nesting with maps that have keys
that are freely defined by the model writer (Switch, value, on,
etc.); the latter usually use the named<> production in the formal
syntax of SDF (Appendix A), while the former SDF-defined vocabulary
items are often, but not always, called _qualities_.
2.2. Elements of an SDF model
The SDF language uses six predefined Class Name Keywords for modeling
connected Things which are illustrated in Figure 2.
Koster, et al. Expires 1 September 2024 [Page 9]
Internet-Draft SDF (Semantic Definition Format) February 2024
,--------.
|sdfThing|
|--------|
`--------'
,---------.
|sdfObject|
|---------|
`---------'
,-----------. ,---------. ,--------.
|sdfProperty| |sdfAction| |sdfEvent|
|-----------| |---------| |--------|
`-----------' `---------' `--------'
|
,-------.
|sdfData|
|-------|
`-------'
Figure 2: Main classes used in SDF models
The six main Class Name Keywords are discussed below.
2.2.1. sdfObject
sdfObjects, the items listed in an sdfObject definition group, are
the main "atom" of reusable semantics for model construction. The
concept aligns in scope with common definition items from many IoT
modeling systems, for example ZigBee Clusters [ZCL], OMA SpecWorks
LwM2M Objects [OMA], and OCF Resource Types [OCF].
An sdfObject definition contains a set of sdfProperty, sdfAction, and
sdfEvent definitions that describe the interaction affordances
associated with some scope of functionality.
For the granularity of definition, sdfObject definitions are meant to
be kept narrow enough in scope to enable broad reuse and
interoperability. For example, defining a light bulb using separate
sdfObject definitions for on/off control, dimming, and color control
affordances will enable interoperable functionality to be configured
for diverse product types. An sdfObject definition for a common on/
off control may be used to control may different kinds of Things that
require on/off control.
Koster, et al. Expires 1 September 2024 [Page 10]
Internet-Draft SDF (Semantic Definition Format) February 2024
The presence of one or both of the optional qualities "minItems" and
"maxItems" defines the sdfObject as an array, i.e., all the
affordances defined for the sdfObject exist a number of times,
indexed by a number constrained to be between minItems and maxItems,
inclusive, if given. (Note: Setting "minItems" to zero and leaving
out "maxItems" puts the minimum constraints on that array.)
2.2.2. sdfProperty
sdfProperty is used to model elements of state within Things modeled
by the enclosing grouping.
A named definition entry in an sdfProperty may be associated with
some protocol affordance to enable the application to obtain the
state variable and, optionally, modify the state variable.
Additionally, some protocols provide for in-time reporting of state
changes. (These three aspects are described by the qualities
readable, writable, and observable defined for an sdfProperty.)
Definitions in sdfProperty groups include the definitions from
sdfData groups, however, they actually also declare that a Property
with the given qualities potentially is present in the containing
sdfObject.
For definitions in sdfProperty and sdfData, SDF provides qualities
that can constrain the structure and values of data allowed in the
interactions modeled by them, as well as qualities that associate
semantics to these data, such as engineering units and unit scaling
information.
For the data definition within sdfProperty or sdfData, SDF borrows
some vocabulary proposed for the drafts 4 [JSO4] [JSO4V] and 7 [JSO7]
[JSO7V] of the json-schema.org "JSON Schema" format (collectively
called JSO here), enhanced by qualities that are specific to SDF.
Details about the JSO-inspired vocabulary are in Appendix C. For
base SDF, data are constrained to be of simple types (number, string,
Boolean), JSON maps composed of named data, and arrays of these
types. Syntax extension points are provided that can be used to
provide richer types in a future extension of this specification
(possibly more of which can be borrowed from json-schema.org).
Note that sdfProperty definitions (and sdfData definitions in
general) are not intended to constrain the formats of data used for
communication over network interfaces. Where needed, data
definitions for payloads of protocol messages are expected to be part
of the protocol binding.
Koster, et al. Expires 1 September 2024 [Page 11]
Internet-Draft SDF (Semantic Definition Format) February 2024
2.2.3. sdfAction
The sdfAction group contains declarations of Actions, model
affordances that, when triggered, have more effect than just reading,
updating, or observing Thing state, often resulting in some outward
physical effect (which, itself, cannot be modeled in SDF). From a
programmer's perspective, they might be considered to be roughly
analogous to method calls.
Actions may have data parameters; these are modeled as a single item
of input data and output data, each. (Where multiple parameters need
to be modeled, an "object" type can be used to combine these
parameters into one.) Actions may be long-running, that is to say
that the effects may not take place immediately as would be expected
for an update to an sdfProperty; the effects may play out over time
and emit action results. Actions may also not always complete and
may result in application errors, such as an item blocking the
closing of an automatic door.
One idiom for giving an action initiator status and control about the
ongoing action is to provide a URI for an ephemeral "action resource"
in the sdfAction output data, allowing the action to deliver
immediate feedback (including errors that prevent the action from
starting) and the action initiator to use the action resource for
further observation or modification of the ongoing action (including
canceling it). Base SDF does not provide any tailored support for
describing such action resources; an extension for modeling links in
more detail (for instance, [I-D.bormann-asdf-sdftype-link]) may be
all that is needed to fully enable modeling them.
Actions may have (or lack) qualities of idempotence and side-effect
safety.
Base SDF only provides data constraint modeling and semantics for the
input and output data of definitions in sdfAction groups. Again,
data definitions for payloads of protocol messages, and detailed
protocol settings for invoking the action, are expected to be part of
the protocol binding.
2.2.4. sdfEvent
The sdfEvent group contains declarations of Events, which can model
affordances that inform about "happenings" associated with a Thing
modeled by the enclosing sdfObject; these may result in a signal
being stored or emitted as a result.
Koster, et al. Expires 1 September 2024 [Page 12]
Internet-Draft SDF (Semantic Definition Format) February 2024
Note that there is a trivial overlap with sdfProperty state changes,
which may also be defined as events but are not generally required to
be defined as such. However, Events may exhibit certain ordering,
consistency, and reliability requirements that are expected to be
supported in various implementations of sdfEvent that do distinguish
sdfEvent from sdfProperty. For instance, while a state change may
simply be superseded by another state change, some events are
"precious" and need to be preserved even if further events follow.
Base SDF only provides data constraint modeling and semantics for the
output data of Event affordances. Again, data definitions for
payloads of protocol messages, and detailed protocol settings for
invoking the action, are expected to be part of the protocol binding.
2.2.5. sdfData
Definitions in sdfData groups do not themselves specify affordances.
These definitions are provided separately from those in sdfProperty
groups to enable common modeling patterns, data constraints, and
semantic anchor concepts to be factored out for data items that make
up sdfProperty items and serve as input and output data for sdfAction
and sdfEvent items. The sdfData definitions only spring to life by
being referenced in one of these contexts (directly or indirectly via
some other sdfData definitions).
It is a common use case for such a data definition to be shared
between an sdfProperty item and input or output parameters of an
sdfAction or output data provided by an sdfEvent. sdfData definitions
also enable factoring out extended application data types such as
mode and machine state enumerations to be reused across multiple
definitions that have similar basic characteristics and requirements.
2.2.6. sdfThing
Back at the top level, the sdfThing group enables definition of
models for complex devices that will use one or more sdfObject
definitions. Like sdfObject, sdfThing groups also allow for
including interaction affordances, sdfData, as well as "minItems" and
"maxItems" qualities. Therefore, they can be seen as a superset of
sdfObject groups, additionally allowing for composition.
As a result, an sdfThing directly or indirectly contains a set of
sdfProperty, sdfAction, and sdfEvent definitions that describe the
interaction affordances associated with some scope of functionality.
A definition in an sdfThing group can refine the metadata of the
definitions it is composed of: other definitions in sdfThing groups
or definitions in sdfObject groups.
Koster, et al. Expires 1 September 2024 [Page 13]
Internet-Draft SDF (Semantic Definition Format) February 2024
2.3. Member names: Given Names and Quality Names
SDF documents are JSON maps that mostly employ JSON maps as member
values, which in turn mostly employ JSON maps as their member values,
and so on. This nested structure of JSON maps creates a tree, where
the edges are the member names (map keys) used in these JSON maps.
(In certain cases, where member names are not needed, JSON arrays may
be interspersed in this tree.)
2.3.1. Given Names and Quality Names
For any particular JSON map in an SDF document, the set of member
names that are used is either of:
* A set of "_Quality Names_", where the entries in the map are
Qualities. Quality Names are defined by the present specification
and its extensions, together with specific semantics to be
associated with the member value given with a certain Quality
Name.
* A set of "_Given Names_", where the entries in the map are
separate entities (definitions, declarations, etc.) that each have
names that are chosen by the SDF document author in order that
these names can be employed by a user of that model.
In a path from the root of the tree to any leaf, Quality Names and
Given Names roughly alternate (with the information block,
Section 3.1, as a prominent exception).
The meaning of the JSON map that is the member value associated with
a Given Name is derived from the Quality Name that was used as the
member name associated to the parent. In the CDDL grammar given in
Appendix A, JSON maps with member names that are Given Names are
defined using the CDDL generic rule reference named<membervalues>,
where membervalues is in turn the structure of the member values of
the JSON map, i.e., the value of the member named by the Given Name.
As quality-named maps and given-named maps roughly alternate in a
path down the tree, membervalues is usually a map built from Quality
Names as keys.
2.3.2. Hierarchical Names
From the outside of a specification, Given Names are usually used as
part of a hierarchical name that looks like a JSON pointer [RFC6901],
itself generally rooted in (used as the fragment identifier in) an
outer namespace that looks like an https:// URL (see Section 4).
Koster, et al. Expires 1 September 2024 [Page 14]
Internet-Draft SDF (Semantic Definition Format) February 2024
As Quality Names and Given Names roughly alternate in a path into the
model, the JSON pointer part of the hierarchical name also alternates
between Quality Names and Given Names.
Note that the actual Given Names may need to be encoded when
specified via the JSON pointer fragment identifier syntax, and that
there are two layers of such encoding: tilde encoding of ~ and / as
per Section 3 of [RFC6901], and then percent encoding of the tilde-
encoded name into a valid URI fragment as per Section 6 of [RFC6901].
For example, when a model is using the Given Name
warning/danger alarm
(with an embedded slash and a space) for an sdfObject, that sdfObject
may need to be referenced as
#/sdfObject/warning~1danger%20alarm
To sidestep potential interoperability problems, it is probably wise
to avoid characters in Given Names that need such encoding (Quality
Names are already defined in such a way that they never do).
2.3.3. Extensibility of Given Names and Quality Names
In SDF, both Quality Names and Given Names are _extension points_.
This is more obvious for Quality Names: Extending SDF is mostly done
by defining additional qualities. To enable non-conflicting third
party extensions to SDF, qualified names (names with an embedded
colon) can be used as Quality Names.
A nonqualified Quality Name is composed of ASCII letters, digits, and
$ signs, starting with a lower case letter or a $ sign (i.e., using a
pattern of "[a-z$][A-Za-z$0-9]*"). Names with $ signs are intended
to be used for functions separate from most other names; for
instance, in this specification $comment is used for the comment
quality (the presence or absence of a $comment quality does not
change the meaning of the SDF model). Names that are composed of
multiple English words can use the "lowerCamelCase" convention
[CamelCase] for indicating the word boundaries; no other use is
intended for upper case letters in quality names.
A qualified Quality Name is composed of a Quality Name Prefix, a :
(colon) character, and a nonqualified Quality Name. Quality Name
Prefixes are registered in the "Quality Name Prefixes" sub-registry
in the "SDF Parameters" registry (Section 7.4.1); they are composed
of lower case ASCII letters and digits, starting with a lower case
ASCII letter (i.e., using a pattern of "[a-z][a-z0-9]*").
Koster, et al. Expires 1 September 2024 [Page 15]
Internet-Draft SDF (Semantic Definition Format) February 2024
Given Names are not restricted by the formal SDF syntax. To enable
non-surprising name translations in tools, combinations of ASCII
alphanumeric characters and - (ASCII hyphen/minus) are preferred,
typically employing kebab-case for names constructed out of multiple
words [KebabCase]. ASCII hyphen/minus can then unambiguously be
translated to an ASCII _ underscore character and back depending on
the programming environment. Some styles also allow a dot . in given
names. Given Names are often sufficiently self-explanatory that they
can be used in place of the label quality if that is not given. In
turn, if a given name turns out too complicated, a more elaborate
label can be given and the given name kept simple. Base SDF does not
address internationalization of given names.
Further, to enable Given Names to have a more powerful role in
building global hierarchical names, an extension is planned that
makes use of qualified names for Given Names. So, until that
extension is defined, Given Names with (one or more) embedded colons
are reserved and MUST NOT be used in an SDF document.
All names in SDF are case-sensitive.
3. SDF structure
SDF definitions are contained in SDF documents, together with data
about the SDF document itself (information block). Definitions and
declarations from additional SDF documents can be referenced;
together with the definitions and declarations in the referencing SDF
document they build the SDF model expressed by that SDF document.
Each SDF document is represented as a single JSON map. This map has
three blocks: the information block, the namespaces block, and the
definitions block.
3.1. Information block
The information block contains generic metadata for the SDF document
itself and all included definitions. To enable tool integration, the
information block is optional in the grammar of SDF; most processes
for working with SDF documents will have policies that only SDF
documents with an info block can be processed. It is therefore
RECOMMENDED that SDF validator tools emit a warning when no
information block is found.
The keyword (map key) that defines an information block is "info".
Its value is a JSON map in turn, with a set of entries that represent
qualities that apply to the included definition.
Qualities of the information block are shown in Table 1.
Koster, et al. Expires 1 September 2024 [Page 16]
Internet-Draft SDF (Semantic Definition Format) February 2024
+=============+=========+==========+==========================+
| Quality | Type | Required | Description |
+=============+=========+==========+==========================+
| title | string | no | A short summary to be |
| | | | displayed in search |
| | | | results, etc. |
+-------------+---------+----------+--------------------------+
| description | string | no | Long-form text |
| | | | description (no |
| | | | constraints) |
+-------------+---------+----------+--------------------------+
| version | string | no | The incremental version |
| | | | of the definition |
+-------------+---------+----------+--------------------------+
| modified | string | no | Time of the latest |
| | | | modification |
+-------------+---------+----------+--------------------------+
| copyright | string | no | Link to text or embedded |
| | | | text containing a |
| | | | copyright notice |
+-------------+---------+----------+--------------------------+
| license | string | no | Link to text or embedded |
| | | | text containing license |
| | | | terms |
+-------------+---------+----------+--------------------------+
| features | array | no | List of extension |
| | of | | features used |
| | strings | | |
+-------------+---------+----------+--------------------------+
| $comment | string | no | Source code comments |
| | | | only, no semantics |
+-------------+---------+----------+--------------------------+
Table 1: Qualities of the Information Block
Koster, et al. Expires 1 September 2024 [Page 17]
Internet-Draft SDF (Semantic Definition Format) February 2024
The version quality is used to indicate version information about the
set of definitions in the SDF document. The version is RECOMMENDED
to be lexicographically increasing over the life of a model: a newer
model always has a version string that string-compares higher than
all previous versions. This is easily achieved by following the
convention to start the version with an [RFC3339] date-time or, if
new versions are generated less frequently than once a day, just the
full-date (i.e., YYYY-MM-DD); in many cases, that will be all that is
needed (see Figure 1 for an example). This specification does not
give a strict definition for the format of the version string but
each using system or organization should define internal structure
and semantics to the level needed for their use. If no further
details are provided, a date-time or full-date in this field can be
assumed to indicate the latest update time of the definitions in the
SDF document.
The modified quality can be used with a value using [RFC3339] date-
time (with Z for time-zone) or full-date format to express time of
the latest revision of the definitions.
The license string is preferably either a URI that points to a web
page with an unambiguous definition of the license, or an [SPDX]
license identifier. (As an example, for models to be handled by the
One Data Model liaison group, this license identifier will typically
be "BSD-3-Clause".)
The features quality can be used to list names of critical (i.e.,
cannot be safely ignored) SDF extension features that need to be
understood for the definitions to be properly processed. Extension
feature names will be specified in extension documents.
3.2. Namespaces block
The namespaces block contains the namespace map and the
defaultNamespace setting.
The namespace map is a map from short names for URIs to the namespace
URIs themselves.
The defaultNamespace setting selects one of the entries in the
namespace map by giving its short name. The associated URI (value of
this entry) becomes the default namespace for the SDF document.
Koster, et al. Expires 1 September 2024 [Page 18]
Internet-Draft SDF (Semantic Definition Format) February 2024
+==================+========+==========+=======================+
| Quality | Type | Required | Description |
+==================+========+==========+=======================+
| namespace | map | no | Defines short names |
| | | | mapped to namespace |
| | | | URIs, to be used as |
| | | | identifier prefixes |
+------------------+--------+----------+-----------------------+
| defaultNamespace | string | no | Identifies one of the |
| | | | prefixes in the |
| | | | namespace map to be |
| | | | used as a default in |
| | | | resolving identifiers |
+------------------+--------+----------+-----------------------+
Table 2: Namespaces Block
The following example declares a set of namespaces and defines cap as
the default namespace. By convention, the values in the namespace
map contain full URIs without a fragment identifier, and the fragment
identifier is then added, if needed, where the namespace entry is
used.
"namespace": {
"cap": "https://example.com/capability/cap",
"zcl": "https://zcl.example.com/sdf"
},
"defaultNamespace": "cap"
If no defaultNamespace setting is given, the SDF document does not
contribute to a global namespace (all definitions remain local to the
model and are not accessible for re-use by other models). As the
defaultNamespace is set by giving a namespace short name, its
presence requires a namespace map that contains a mapping for that
namespace short name.
If no namespace map is given, no short names for namespace URIs are
set up, and no defaultNamespace can be given.
3.3. Definitions block
The Definitions block contains one or more groups, each identified by
a Class Name Keyword (there can only be one group per keyword; the
actual grouping is just a shortcut and does not carry any specific
semantics). The value of each group is a JSON map, the keys of which
serve for naming the individual definitions in this group, and the
corresponding values provide a set of qualities (name-value pairs)
for the individual definition. (In short, we speak of the map
Koster, et al. Expires 1 September 2024 [Page 19]
Internet-Draft SDF (Semantic Definition Format) February 2024
entries as "named sets of qualities".)
Each group may contain zero or more definitions. Each identifier
defined creates a new type and term in the target namespace.
Declarations have a scope of the definition block they are directly
contained in.
A definition may in turn contain other definitions. Each definition
is a named set of qualities, i.e., it consists of the newly defined
identifier and a set of key-value pairs that represent the defined
qualities and contained definitions.
An example for an sdfObject definition is given in Figure 3:
"sdfObject": {
"foo": {
"sdfProperty": {
"bar": {
"type": "boolean"
}
}
}
}
Figure 3: Example sdfObject definition
This example defines an sdfObject "foo" that is defined in the
default namespace (full address: #/sdfObject/foo), containing a
property that can be addressed as #/sdfObject/foo/sdfProperty/bar,
with data of type boolean.
Often, definitions are also declarations: the definition of the entry
"bar" in the property "foo" means that data corresponding to the
"foo" property in a property interaction offered by Thing can have
zero or one components modeled by "bar". Entries within sdfProperty,
sdfAction, and sdfEvent, in turn within sdfObject or sdfThing
entries, are declarations; entries within sdfData are not.
Similarly, sdfObject or sdfThing entries within an sdfThing
definition specify that the interactions offered by a Thing modeled
by this sdfThing include the interactions modeled by the nested
sdfObject or sdfThing.
Koster, et al. Expires 1 September 2024 [Page 20]
Internet-Draft SDF (Semantic Definition Format) February 2024
3.4. Top-level Affordances and sdfData
Besides their placement within an sdfObject or sdfThing, affordances
(i.e., sdfProperty, sdfAction, and sdfEvent) as well as sdfData can
also be placed at the top level of an SDF document. Since they are
not associated with an sdfObject or sdfThing, these kinds of
definitions are intended to be re-used via the sdfRef mechanism (see
Section 4.4).
4. Names and namespaces
SDF documents may contribute to a global namespace, and may reference
elements from that global namespace. (An SDF document that does not
set a defaultNamespace does not contribute to a global namespace.)
4.1. Structure
Global names look exactly like https:// URIs with attached fragment
identifiers.
There is no intention to require that these URIs can be dereferenced.
(However, as future extensions of SDF might find a use for
dereferencing global names, the URI should be chosen in such a way
that this may become possible in the future. See also
[I-D.bormann-t2trg-deref-id] for a discussion of dereferenceable
identifiers.)
The absolute URI of a global name should be a URI as per Section 3 of
[RFC3986], with a scheme of "https" and a path (hier-part in
[RFC3986]). For base SDF, the query part should not be used (it
might be used in extensions).
The fragment identifier is constructed as per Section 6 of [RFC6901].
4.2. Contributing global names
The fragment identifier part of a global name defined in an SDF
document is constructed from a JSON pointer that selects the element
defined for this name in the SDF document.
The absolute URI part is a copy of the default namespace, i.e., the
default namespace is always the target namespace for a name for which
a definition is contributed. When emphasizing that name definitions
are contributed to the default namespace, we therefore also call it
the "target namespace" of the SDF document.
For instance, in Figure 1, definitions for the following global names
are contributed:
Koster, et al. Expires 1 September 2024 [Page 21]
Internet-Draft SDF (Semantic Definition Format) February 2024
* https://example.com/capability/cap#/sdfObject/Switch
* https://example.com/capability/cap#/sdfObject/Switch/sdfProperty/
value
* https://example.com/capability/cap#/sdfObject/Switch/sdfAction/on
* https://example.com/capability/cap#/sdfObject/Switch/sdfAction/off
Note the #, which separates the absolute-URI part (Section 4.3 of
[RFC3986]) from the fragment identifier part.
4.3. Referencing global names
A name reference takes the form of the production curie in
[W3C.NOTE-curie-20101216] (note that this excludes the production
safe-curie), but also limiting the IRIs involved in that production
to URIs as per [RFC3986] and the prefixes to ASCII characters
[RFC0020].
A name that is contributed by the current SDF document can be
referenced by a Same-Document Reference as per Section 4.4 of
[RFC3986]. As there is little point in referencing the entire SDF
document, this will be a # followed by a JSON pointer. This is the
only kind of name reference to itself that is possible in an SDF
document that does not set a default namespace.
Name references that point outside the current SDF document need to
contain curie prefixes. These then reference namespace declarations
in the namespaces block.
For example, if a namespace prefix is defined:
"namespace": {
"foo": "https://example.com/"
}
Then this reference to that namespace:
"sdfRef": "foo:#/sdfData/temperatureData"
references the global name:
"https://example.com/#/sdfData/temperatureData"
Note that there is no way to provide a URI scheme name in a curie, so
all references to outside of the document need to go through the
namespace map.
Koster, et al. Expires 1 September 2024 [Page 22]
Internet-Draft SDF (Semantic Definition Format) February 2024
Name references occur only in specific elements of the syntax of SDF:
* copying elements via sdfRef values
* pointing to elements via sdfRequired value elements
4.4. sdfRef
In a JSON map establishing a definition, the keyword sdfRef is used
to copy all of the qualities and enclosed definitions of the
referenced definition, indicated by the included name reference, into
the newly formed definition. (This can be compared to the processing
of the $ref keyword in [JSO7].)
For example, this reference:
"temperatureProperty": {
"sdfRef": "#/sdfData/temperatureData"
}
creates a new definition "temperatureProperty" that contains all of
the qualities defined in the definition at /sdfData/temperatureData.
The sdfRef member need not be the only member of a map. Additional
members may be present with the intention to override parts of the
referenced map or to add new qualities or definitions.
When processing sdfRef, if the target definition contains also sdfRef
(i.e., is based on yet another definition), that MUST be processed as
well.
More formally, for a JSON map that contains an sdfRef member, the
semantics is defined to be as if the following steps were performed:
1. The JSON map that contains the sdfRef member is copied into a
variable named "patch".
2. The sdfRef member of the copy in "patch" is removed.
3. the JSON pointer that is the value of the sdfRef member is
dereferenced and the result is copied into a variable named
"original".
4. The JSON Merge Patch algorithm [RFC7396] is applied to patch the
contents of "original" with the contents of "patch".
5. The result of the Merge Patch is used in place of the value of
the original JSON map.
Koster, et al. Expires 1 September 2024 [Page 23]
Internet-Draft SDF (Semantic Definition Format) February 2024
Note that the formal syntaxes given in Appendices A and B generally
describe the _result_ of applying a merge-patch; the notations are
not powerful enough to describe, for instance, the effect of null
values given with the sdfRef to remove members of JSON maps from the
referenced target. Nonetheless, the syntaxes also give the syntax of
the sdfRef itself, which vanishes during the resolution; in many
cases therefore even merge-patch inputs will validate with these
formal syntaxes.
Given the example (Figure 1), and the following definition:
{
"info": {
"title": "Example light switch using sdfRef"
},
"namespace": {
"cap": "https://example.com/capability/cap"
},
"defaultNamespace": "cap",
"sdfObject": {
"BasicSwitch": {
"sdfRef": "cap:#/sdfObject/Switch",
"sdfAction": {
"toggle": null
}
}
}
}
The resulting definition of the "BasicSwitch" sdfObject would be
identical to the definition of the "Switch" sdfObject except it would
not contain the "toggle" Action.
Koster, et al. Expires 1 September 2024 [Page 24]
Internet-Draft SDF (Semantic Definition Format) February 2024
{
"info": {
"title": "Example light switch using sdfRef"
},
"namespace": {
"cap": "https://example.com/capability/cap"
},
"defaultNamespace": "cap",
"sdfObject": {
"BasicSwitch": {
"sdfProperty": {
"value": {
"description":
"The state of the switch; false for off and true for on.",
"type": "boolean"
}
},
"sdfAction": {
"on": {
"description":
"Turn the switch on; equivalent to setting value to true."
},
"off": {
"description":
"Turn the switch off; equivalent to setting value to false."
}
}
}
}
}
4.4.1. Resolved models
A model where all sdfRef references are processed as described in
Section 4.4 is called a resolved model.
For example, given the following sdfData definitions:
Koster, et al. Expires 1 September 2024 [Page 25]
Internet-Draft SDF (Semantic Definition Format) February 2024
"sdfData": {
"Coordinate" : {
"type": "number", "unit": "m"
},
"X-Coordinate" : {
"sdfRef" : "#/sdfData/Coordinate",
"description":
"Distance from the base of the Thing along the X axis."
},
"Non-neg-X-Coordinate" : {
"sdfRef": "#/sdfData/X-Coordinate",
"minimum": 0
}
}
After resolving the definitions would look as follows:
"sdfData": {
"Coordinate" : {
"type": "number", "unit": "m"
},
"X-Coordinate" : {
"description":
"Distance from the base of the Thing along the X axis.",
"type": "number", "unit": "m"
},
"Non-neg-X-Coordinate" : {
"description":
"Distance from the base of the Thing along the X axis.",
"minimum": 0, "type": "number", "unit": "m"
}
}
4.5. sdfRequired
The keyword sdfRequired is provided to apply a constraint that
defines for which declarations the corresponding data are mandatory
in a Thing modeled by the current definition.
The value of sdfRequired is an array of references, each indicating
one or more declarations that are mandatory to be represented.
References in this array can be SDF names (JSON Pointers), or one of
two abbreviated reference formats:
* a text string with a "referenceable-name", i.e., an affordance
name or grouping name. All affordance declarations that are
directly (i.e., not nested further in another grouping) in the
Koster, et al. Expires 1 September 2024 [Page 26]
Internet-Draft SDF (Semantic Definition Format) February 2024
same grouping and that carry this name (there can be multiple
ones, one per affordance type) are declared to be mandatory to be
represented. The same applies for groupings made mandatory within
groupings containing them.
* the Boolean value true. The affordance/grouping itself that
carries the sdfRequired keyword is declared to be mandatory to be
represented.
Note that referenceable-names are not subject to the encoding JSON
pointers require as discussed in Section 2.3.2. To ensure that
referenceable-names are reliably distinguished from JSON pointers,
they are defined such that they cannot contain ":" or "#" characters
(see rule referenceable-name in Appendix A). (If these characters
are indeed contained in a Given Name, a JSON pointer needs to be
formed instead in order to reference it in "sdfRequired", potentially
requiring further path elements as well as JSON pointer encoding.
The need for this is best avoided by choosing Given Names without
these characters.)
The example in Figure 4 shows two required elements in the sdfObject
definition for "temperatureWithAlarm", the sdfProperty
"currentTemperature", and the sdfEvent "overTemperatureEvent". The
example also shows the use of JSON pointer with "sdfRef" to use a
pre-existing definition in this definition, for the "alarmType" data
(sdfOutputData) produced by the sdfEvent "overTemperatureEvent".
Koster, et al. Expires 1 September 2024 [Page 27]
Internet-Draft SDF (Semantic Definition Format) February 2024
"sdfObject": {
"temperatureWithAlarm": {
"sdfRequired": [
"#/sdfObject/temperatureWithAlarm/sdfProperty/currentTemperature",
"#/sdfObject/temperatureWithAlarm/sdfEvent/overTemperatureEvent"
],
"sdfData":{
"temperatureData": {
"type": "number"
}
},
"sdfProperty": {
"currentTemperature": {
"sdfRef": "#/sdfObject/temperatureWithAlarm/sdfData/temperatureData"
}
},
"sdfEvent": {
"overTemperatureEvent": {
"sdfOutputData": {
"type": "object",
"properties": {
"alarmType": {
"sdfRef": "cap:#/sdfData/alarmTypes/quantityAlarms",
"const": "OverTemperatureAlarm"
},
"temperature": {
"sdfRef": "#/sdfObject/temperatureWithAlarm/sdfData/temperatureData"
}
}
}
}
}
}
}
Figure 4: Using sdfRequired
In Figure 4, the same sdfRequired can also be represented in short
form:
"sdfRequired": ["currentTemperature", "overTemperatureEvent"]
Or, for instance "overTemperatureEvent" could carry
"overTemperatureEvent": {
"sdfRequired": [true],
"...": "..."
}
Koster, et al. Expires 1 September 2024 [Page 28]
Internet-Draft SDF (Semantic Definition Format) February 2024
4.6. Common Qualities
Definitions in SDF share a number of qualities that provide metadata
for them. These are listed in Table 3. None of these qualities are
required or have default values that are assumed if the quality is
absent. If a label is required for an application and no label is
given in the SDF model, the last part (reference-token, Section 3 of
[RFC6901]) of the JSON pointer to the definition can be used.
+=============+==============+=============================+
| Quality | Type | Description |
+=============+==============+=============================+
| description | string | long text (no constraints) |
+-------------+--------------+-----------------------------+
| label | string | short text (no constraints) |
+-------------+--------------+-----------------------------+
| $comment | string | source code comments only, |
| | | no semantics |
+-------------+--------------+-----------------------------+
| sdfRef | sdf-pointer | (see Section 4.4) |
+-------------+--------------+-----------------------------+
| sdfRequired | pointer-list | (see Section 4.5, used in |
| | | affordances or groupings) |
+-------------+--------------+-----------------------------+
Table 3: Common Qualities
4.7. Data Qualities
Data qualities are used in sdfData and sdfProperty definitions, which
are named sets of data qualities (abbreviated as named-sdq).
Appendix C lists data qualities inspired by the various proposals at
json-schema.org; the intention is that these (information model
level) qualities are compatible with the (data model) semantics from
the versions of the json-schema.org proposal they were imported from.
Table 4 lists data qualities defined specifically for the present
specification.
Koster, et al. Expires 1 September 2024 [Page 29]
Internet-Draft SDF (Semantic Definition Format) February 2024
+===============+================+====================+=========+
| Quality | Type | Description | Default |
+===============+================+====================+=========+
| (common) | | Section 4.6 | |
+---------------+----------------+--------------------+---------+
| unit | string | unit name (note 1) | N/A |
+---------------+----------------+--------------------+---------+
| nullable | boolean | indicates a null | true |
| | | value is available | |
| | | for this type | |
+---------------+----------------+--------------------+---------+
| contentFormat | string | content type (IANA | N/A |
| | | media type string | |
| | | plus parameters), | |
| | | encoding (note 2) | |
+---------------+----------------+--------------------+---------+
| sdfType | string | sdfType | N/A |
| | (Section | enumeration | |
| | 4.7.1) | (extensible) | |
+---------------+----------------+--------------------+---------+
| sdfChoice | named set of | named alternatives | N/A |
| | data qualities | | |
| | (Section | | |
| | 4.7.2) | | |
+---------------+----------------+--------------------+---------+
| enum | array of | abbreviation for | N/A |
| | strings | string-valued | |
| | | named alternatives | |
+---------------+----------------+--------------------+---------+
Table 4: SDF-defined Qualities of sdfData
1. Note that the quality unit was called units in earlier drafts of
SDF. The unit name SHOULD be as per the SenML Units Registry or
the Secondary Units Registry in [IANA.senml] as specified by
Sections 4.5.1 and 12.1 of [RFC8428] and Section 3 of [RFC8798],
respectively.
Exceptionally, if a registration in these registries cannot be
obtained or would be inappropriate, the unit name can also be a
URI that is pointing to a definition of the unit. Note that SDF
processors are not expected to (and normally SHOULD NOT)
dereference these URIs (see also [I-D.bormann-t2trg-deref-id]);
they may be useful to humans, though. A URI unit name is
distinguished from a registered unit name by the presence of a
colon; any registered unit names that contain a colon (at the
time of writing, none) can therefore not be used in SDF.
Koster, et al. Expires 1 September 2024 [Page 30]
Internet-Draft SDF (Semantic Definition Format) February 2024
For use by translators into ecosystems that require URIs for unit
names, the URN sub-namespace "urn:ietf:params:unit" is provided
(Section 7.3); URNs from this sub-namespace MUST NOT be used in a
unit quality, in favor of simply notating the unit name (such as
kg instead of urn:ietf:params:unit:kg).
2. The contentFormat quality follows the Content-Format-Spec as
defined in Section 6 of [RFC9193], allowing for expressing both
numeric and string based Content-Formats.
4.7.1. sdfType
SDF defines a number of basic types beyond those provided by JSON or
JSO. These types are identified by the sdfType quality, which is a
text string from a set of type names defined by the "sdfType values"
sub-registry in the "SDF Parameters" registry (Section 7.4.2). The
sdfType name is composed of lower case ASCII letters, digits, and -
(ASCII hyphen/minus) characters, starting with a lower case ASCII
letter (i.e., using a pattern of "[a-z][-a-z0-9]*"), typically
employing kebab-case for names constructed out of multiple words
[KebabCase].
To aid interworking with JSO implementations, it is RECOMMENDED that
sdfType is always used in conjunction with the type quality inherited
from [JSO7V], in such a way as to yield a common representation of
the type's values in JSON.
Values for sdfType that are defined in this specification are shown
in Table 5. This table also gives a description of the semantics of
the sdfType, the conventional value for type to be used with the
sdfType value, and a conventional JSON representation for values of
the type.
+=============+=============+========+==========================+
| sdfType | Description | type | JSON Representation |
+=============+=============+========+==========================+
| byte-string | A sequence | string | base64url without |
| | of zero or | | padding (Section 3.4.5.2 |
| | more bytes | | of [RFC8949]) |
+-------------+-------------+--------+--------------------------+
| unix-time | A point in | number | POSIX time |
| | civil time | | (Section 3.4.2 of |
| | (note 1) | | [RFC8949]) |
+-------------+-------------+--------+--------------------------+
Table 5: Values defined in base SDF for the sdfType quality
Koster, et al. Expires 1 September 2024 [Page 31]
Internet-Draft SDF (Semantic Definition Format) February 2024
(1) Note that the definition of unix-time does not imply the
capability to represent points in time that fall on leap seconds.
More date/time-related sdfTypes are likely to be added in the sdfType
value registry.
(In earlier drafts of this specification, a similar concept was
called subtype.)
4.7.2. sdfChoice
Data can be a choice of named alternatives, called sdfChoice. Each
alternative is identified by a name (string, key in the outer JSON
map used to represent the overall choice) and a set of dataqualities
(each in an inner JSON map, the value used to represent the
individual alternative in the outer JSON map). Dataqualities that
are specified at the same level as the sdfChoice apply to all choices
in the sdfChoice, except those specific choices where the dataquality
is overridden at the choice level.
sdfChoice merges the functions of two constructs found in [JSO7V]:
* enum
What would have been
"enum": ["foo", "bar", "baz"]
in earlier drafts of this specification, is often best represented
as:
"sdfChoice": {
"foo": { "description": "This is a foonly"},
"bar": { "description":
"As defined in the second world congress"},
"baz": { "description": "From zigbee foobaz"}
}
This allows the placement of other dataqualities such as
description in the example.
If an enum needs to use a data type different from text string,
what would for instance have been:
"type": "number",
"enum": [1, 2, 3]
in earlier drafts of this specification, is represented as:
Koster, et al. Expires 1 September 2024 [Page 32]
Internet-Draft SDF (Semantic Definition Format) February 2024
"type": "number",
"sdfChoice": {
"a-better-name-for-alternative-1": { "const": 1 },
"alternative-2": { "const": 2 },
"the-third-alternative": { "const": 3 }
}
where the string names obviously would be chosen in a way that is
descriptive for what these numbers actually stand for; sdfChoice
also makes it easy to add number ranges into the mix.
(Note that const can also be used for strings as in the previous
example, for instance, if the actual string value is indeed a
crucial element for the data model.)
* anyOf
JSO provides a type union called anyOf, which provides a choice
between anonymous alternatives.
What could have been in JSO:
"anyOf": [
{"type": "array", "minItems": 3, "maxItems": "3",
"items": {"$ref": "#/sdfData/rgbVal"}},
{"type": "array", "minItems": 4, "maxItems": "4",
"items": {"$ref": "#/sdfData/cmykVal"}}
]
can be more descriptively notated in SDF as:
"sdfChoice": {
"rgb": {"type": "array", "minItems": 3, "maxItems": "3",
"items": {"sdfRef": "#/sdfData/rgbVal"}},
"cmyk": {"type": "array", "minItems": 4, "maxItems": "4",
"items": {"sdfRef": "#/sdfData/cmykVal"}}
}
Note that there is no need in SDF for the type intersection construct
allOf or the peculiar type-xor construct oneOf found in [JSO7V].
As a simplification for users of SDF models who are accustomed to the
JSO enum keyword, this is retained, but limited to a choice of text
string values, such that
"enum": ["foo", "bar", "baz"]
is syntactic sugar for
Koster, et al. Expires 1 September 2024 [Page 33]
Internet-Draft SDF (Semantic Definition Format) February 2024
"sdfChoice": {
"foo": { "const": "foo"},
"bar": { "const": "bar"},
"baz": { "const": "baz"}
}
In a single definition, the keyword enum cannot be used at the same
time as the keyword sdfChoice, as the former is just syntactic sugar
for the latter.
5. Keywords for definition groups
The following SDF keywords are used to create definition groups in
the target namespace. All these definitions share some common
qualities as discussed in Section 4.6.
5.1. sdfObject
The sdfObject keyword denotes a group of zero or more sdfObject
definitions. sdfObject definitions may contain or include definitions
of Properties, Actions, Events declared for the sdfObject, as well as
data types (sdfData group) to be used in this or other sdfObjects.
The qualities of an sdfObject include the common qualities,
additional qualities are shown in Table 6. None of these qualities
are required or have default values that are assumed if the quality
is absent.
Koster, et al. Expires 1 September 2024 [Page 34]
Internet-Draft SDF (Semantic Definition Format) February 2024
+=============+===========+================================+
| Quality | Type | Description |
+=============+===========+================================+
| (common) | | Section 4.6 |
+-------------+-----------+--------------------------------+
| sdfProperty | property | zero or more named property |
| | | definitions for this sdfObject |
+-------------+-----------+--------------------------------+
| sdfAction | action | zero or more named action |
| | | definitions for this sdfObject |
+-------------+-----------+--------------------------------+
| sdfEvent | event | zero or more named event |
| | | definitions for this sdfObject |
+-------------+-----------+--------------------------------+
| sdfData | named-sdq | zero or more named data type |
| | | definitions that might be used |
| | | in the above |
+-------------+-----------+--------------------------------+
| minItems | number | (array) Minimum number of |
| | | multiplied affordances in |
| | | array |
+-------------+-----------+--------------------------------+
| maxItems | number | (array) Maximum number of |
| | | multiplied affordances in |
| | | array |
+-------------+-----------+--------------------------------+
Table 6: Qualities of sdfObject
5.2. sdfProperty
The sdfProperty keyword denotes a group of zero or more Property
definitions.
Properties are used to model elements of state.
The qualities of a Property definition include the data qualities
(and thus the common qualities), see Section 4.7, additional
qualities are shown in Table 7.
Koster, et al. Expires 1 September 2024 [Page 35]
Internet-Draft SDF (Semantic Definition Format) February 2024
+============+=========+===============================+=========+
| Quality | Type | Description | Default |
+============+=========+===============================+=========+
| (data) | | Section 4.7 | |
+------------+---------+-------------------------------+---------+
| readable | boolean | Reads are allowed | true |
+------------+---------+-------------------------------+---------+
| writable | boolean | Writes are allowed | true |
+------------+---------+-------------------------------+---------+
| observable | boolean | flag to indicate asynchronous | true |
| | | notification is available | |
+------------+---------+-------------------------------+---------+
Table 7: Qualities of sdfProperty
5.3. sdfAction
The sdfAction keyword denotes a group of zero or more Action
definitions.
Actions are used to model commands and methods which are invoked.
Actions have parameter data that are supplied upon invocation.
The qualities of an Action definition include the common qualities,
additional qualities are shown in Table 8.
+===============+===========+============================+
| Quality | Type | Description |
+===============+===========+============================+
| (common) | | Section 4.6 |
+---------------+-----------+----------------------------+
| sdfInputData | map | data qualities of the |
| | | input data for an Action |
+---------------+-----------+----------------------------+
| sdfOutputData | map | data qualities of the |
| | | output data for an Action |
+---------------+-----------+----------------------------+
| sdfData | named-sdq | zero or more named data |
| | | type definitions that |
| | | might be used in the above |
+---------------+-----------+----------------------------+
Table 8: Qualities of sdfAction
Koster, et al. Expires 1 September 2024 [Page 36]
Internet-Draft SDF (Semantic Definition Format) February 2024
sdfInputData defines the input data of the action. sdfOutputData
defines the output data of the action. As discussed in
Section 2.2.3, a set of data qualities with type "object" can be used
to substructure either data item, with optionality indicated by the
data quality required.
5.4. sdfEvent
The sdfEvent keyword denotes zero or more Event definitions.
Events are used to model asynchronous occurrences that may be
communicated proactively. Events have data elements which are
communicated upon the occurrence of the event.
The qualities of sdfEvent include the common qualities, additional
qualities are shown in Table 9.
+===============+===========+============================+
| Quality | Type | Description |
+===============+===========+============================+
| (common) | | Section 4.6 |
+---------------+-----------+----------------------------+
| sdfOutputData | map | data qualities of the |
| | | output data for an Event |
+---------------+-----------+----------------------------+
| sdfData | named-sdq | zero or more named data |
| | | type definitions that |
| | | might be used in the above |
+---------------+-----------+----------------------------+
Table 9: Qualities of sdfEvent
sdfOutputData defines the output data of the action. As discussed in
Section 2.2.4, a set of data qualities with type "object" can be used
to substructure the output data item, with optionality indicated by
the data quality required.
5.5. sdfData
The sdfData keyword denotes a group of zero or more named data type
definitions (named-sdq).
An sdfData definition provides a reusable semantic identifier for a
type of data item and describes the constraints on the defined type.
It is not itself a declaration, i.e., it does not cause any of these
data items to be included in an affordance definition.
Koster, et al. Expires 1 September 2024 [Page 37]
Internet-Draft SDF (Semantic Definition Format) February 2024
The qualities of sdfData include the data qualities (and thus the
common qualities), see Section 4.7.
6. High Level Composition
The requirements for high level composition include the following:
* The ability to represent products, standardized product types, and
modular products while maintaining the atomicity of sdfObjects.
* The ability to compose a reusable definition block from
sdfObjects, for example a single plug unit of an outlet strip with
on/off control, energy monitor, and optional dimmer sdfObjects,
while retaining the atomicity of the individual sdfObjects.
* The ability to compose sdfObjects and other definition blocks into
a higher level sdfThing that represents a product, while retaining
the atomicity of sdfObjects.
* The ability to enrich and refine a base definition to have
product-specific qualities and quality values, such as unit,
range, and scale settings.
* The ability to reference items in one part of a complex definition
from another part of the same definition, for example to summarize
the energy readings from all plugs in an outlet strip.
6.1. Paths in the model namespaces
The model namespace is organized according to terms that are defined
in the SDF documents that contribute to the namespace. For example,
definitions that originate from an organization or vendor are
expected to be in a namespace that is specific to that organization
or vendor.
The structure of a path in a namespace is defined by the JSON
Pointers to the definitions in the SDF documents in that namespace.
For example, if there is an SDF document defining an sdfObject
"Switch" with an action "on", then the reference to the action would
be "ns:/sdfObject/Switch/sdfAction/on" where ns is the namespace
prefix (short name for the namespace).
6.2. Modular Composition
Modular composition of definitions enables an existing definition
(could be in the same or another SDF document) to become part of a
new definition by including a reference to the existing definition
within the model namespace.
Koster, et al. Expires 1 September 2024 [Page 38]
Internet-Draft SDF (Semantic Definition Format) February 2024
6.2.1. Use of the "sdfRef" keyword to re-use a definition
An existing definition may be used as a template for a new
definition, that is, a new definition is created in the target
namespace which uses the defined qualities of some existing
definition. This pattern will use the keyword sdfRef as a quality of
a new definition with a value consisting of a reference to the
existing definition that is to be used as a template.
In the definition that uses sdfRef, new qualities may be added and
existing qualities from the referenced definition may be overridden.
(Note that JSON maps do not have a defined order, so the SDF
processor may see these overrides before seeing the sdfRef.)
Note that if the referenced definition contains qualities or
definitions that are not valid in the context where the sdfRef is
used (for instance, if an sdfThing definition would be added in an
sdfObject definition), the resulting model, when resolved, may be
invalid.
As a convention, overrides are intended to be used only for further
restricting the set of data values, as shown in Figure 5: any value
for a cable-length also is a valid value for a length, with the
additional restriction that the length cannot be smaller than 5 cm.
(This is labeled as a convention as it cannot be checked in the
general case; a quality of implementation consideration for a tool
might be to provide at least some form of checking.) Note that a
description is provided that overrides the description of the
referenced definition; as this quality is intended for human
consumption there is no conflict with the intended goal.
"sdfData":
"length" : {
"type": "number",
"minimum": 0,
"unit": "m"
"description": "There can be no negative lengths."
}
...
"cable-length" : {
"sdfRef": "#/sdfData/length"
"minimum": 5e-2,
"description": "Cables must be at least 5 cm."
}
Figure 5
Koster, et al. Expires 1 September 2024 [Page 39]
Internet-Draft SDF (Semantic Definition Format) February 2024
6.3. sdfThing
An sdfThing is a set of declarations and qualities that may be part
of a more complex model. For example, the sdfObject declarations
that make up the definition of a single socket of an outlet strip
could be encapsulated in an sdfThing, which itself could be used in a
declaration in the sdfThing definition for the outlet strip (see
Figure 6 in Appendix D.1 for an example SDF model).
sdfThing definitions carry semantic meaning, such as a defined
refrigerator compartment and a defined freezer compartment, making up
a combination refrigerator-freezer product. An sdfThing may be
composed of sdfObjects and other sdfThings. It can also contain
sdfData definitions, as well as declarations of interaction
affordances itself, such as a status (on/off) for the refrigerator-
freezer as a whole (see Figure 7 in Appendix D.2 for an example SDF
model illustrating these aspects).
The qualities of sdfThing are shown in Table 10. Analogous to
sdfObject, the presence of one or both of the optional qualities
"minItems" and "maxItems" defines the sdfThing as an array.
Koster, et al. Expires 1 September 2024 [Page 40]
Internet-Draft SDF (Semantic Definition Format) February 2024
+=============+===========+=============================+
| Quality | Type | Description |
+=============+===========+=============================+
| (common) | | Section 4.6 |
+-------------+-----------+-----------------------------+
| sdfThing | thing | |
+-------------+-----------+-----------------------------+
| sdfObject | object | |
+-------------+-----------+-----------------------------+
| sdfProperty | property | zero or more named property |
| | | definitions for this thing |
+-------------+-----------+-----------------------------+
| sdfAction | action | zero or more named action |
| | | definitions for this thing |
+-------------+-----------+-----------------------------+
| sdfEvent | event | zero or more named event |
| | | definitions for this thing |
+-------------+-----------+-----------------------------+
| sdfData | named-sdq | zero or more named data |
| | | type definitions that might |
| | | be used in the above |
+-------------+-----------+-----------------------------+
| minItems | number | (array) Minimum number of |
| | | multiplied affordances in |
| | | array |
+-------------+-----------+-----------------------------+
| maxItems | number | (array) Maximum number of |
| | | multiplied affordances in |
| | | array |
+-------------+-----------+-----------------------------+
Table 10: Qualities of sdfThing
7. IANA Considerations
// RFC Ed.: throughout this section, please replace RFC XXXX with
// this RFC number, and remove this note.
7.1. Media Type
IANA is requested to add the following Media-Type to the "Media
Types" registry.
Koster, et al. Expires 1 September 2024 [Page 41]
Internet-Draft SDF (Semantic Definition Format) February 2024
+==========+======================+=======================+
| Name | Template | Reference |
+==========+======================+=======================+
| sdf+json | application/sdf+json | RFC XXXX, Section 7.1 |
+----------+----------------------+-----------------------+
Table 11: Media Type Registration for SDF
Type name: application
Subtype name: sdf+json
Required parameters: none
Optional parameters: none
Encoding considerations: binary (JSON is UTF-8-encoded text)
Security considerations: Section 8 of RFC XXXX
Interoperability considerations: none
Published specification: Section 7.1 of RFC XXXX
Applications that use this media type: Tools for data and
interaction modeling in the Internet of Things and related
environments
Fragment identifier considerations: A JSON Pointer fragment
identifier may be used, as defined in Section 6 of [RFC6901].
Additional information: Magic number(s): n/a
File extension(s): .sdf.json
Windows Clipboard Name: "Semantic
Definition Format (SDF) for Data and Interactions of Things"
Macintosh file type code(s): n/a
Macintosh Universal Type Identifier code: o
rg.ietf.sdf-json
conforms to public.text
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
7.2. Content-Format
This document adds the following Content-Format to the "CoAP Content-
Formats", within the "Constrained RESTful Environments (CoRE)
Parameters" registry, where TBD1 comes from the "IETF Review" 256-999
range.
Koster, et al. Expires 1 September 2024 [Page 42]
Internet-Draft SDF (Semantic Definition Format) February 2024
+======================+================+======+===========+
| Content Type | Content Coding | ID | Reference |
+======================+================+======+===========+
| application/sdf+json | - | TBD1 | RFC XXXX |
+----------------------+----------------+------+-----------+
Table 12: SDF Content-format Registration
// RFC Ed.: please replace TBD1 with the assigned ID, remove the
requested range, and remove this note.
// RFC Ed.: please replace RFC XXXX with this RFC number and remove
this note.
7.3. IETF URN Sub-namespace for Unit Names (urn:ietf:params:unit)
IANA is requested to register the following value in the "IETF URN
Sub-namespace for Registered Protocol Parameter Identifiers" registry
in [IANA.params], following the template in [RFC3553]:
Registry name: unit
Specification: RFC XXXX
Repository: combining the symbol values from the SenML Units
Registry and the Secondary Units Registry in [IANA.senml] as
specified by Sections 4.5.1 and 12.1 of [RFC8428] and Section 3 of
[RFC8798], respectively (which by the registration policy are
guaranteed to be non-overlapping).
Index value: Percent-encoding (Section 2.1 of [RFC3986]) is required
of any characters in unit names as required by ABNF rule "pchar"
in Section 3.3 of [RFC3986], specifically at the time of writing
for the unit names "%" (deprecated in favor of "/"), "%RH", "%EL".
7.4. Registries
IANA is requested to create an "SDF Parameters" registry, with the
sub-registries defined in this Section.
7.4.1. Quality Name Prefixes
IANA is requested to create a "Quality Name Prefixes" sub-registry in
the "SDF Parameters" registry, with the following template:
Prefix: A name composed of lower case ASCII letters and digits,
starting with a lower case ASCII letter (i.e., using a pattern of
"[a-z][a-z0-9]*").
Koster, et al. Expires 1 September 2024 [Page 43]
Internet-Draft SDF (Semantic Definition Format) February 2024
Contact: A contact point for the organization that assigns quality
names with this prefix.
Quality Name Prefixes are intended to be registered by organizations
that intend to define quality names constructed with an organization-
specifix prefix (Section 2.3.3).
The registration policy is Expert Review as per Section 4.5 of
[BCP26]. The instructions to the Expert are to ascertain that the
organization will handle quality names constructed using their prefix
in a way that roughly achieves the objectives for an IANA registry
that support interoperability of SDF models employing these quality
names, including:
* Stability, "stable and permanent";
* Transparency, "readily available", "in sufficient detail"
(Section 4.6 of [BCP26]).
The Expert will take into account that other organizations operate in
different ways than the IETF, and that as a result some of these
overall objectives will be achieved in a different way and to a
different level of comfort.
The "Quality Name Prefixes" sub-registry starts out empty.
7.4.2. sdfType Values
IANA is requested to create a "sdfType values" sub-registry in the
"SDF Parameters" registry, with the following template:
Name: A name composed of lower case ASCII letters, digits and -
(ASCII hyphen/minus) characters, starting with a lower case ASCII
letter (i.e., using a pattern of "[a-z][-a-z0-9]*").
Description: A short description of the information model level
structure and semantics
type: The value of the quality "type" to be used with this sdfType
JSON Representation A short description of a JSON representation
that can be used for this sdfType. This MUST be consistent with
the type.
Reference: A more detailed specification of meaning and use of
sdfType.
Koster, et al. Expires 1 September 2024 [Page 44]
Internet-Draft SDF (Semantic Definition Format) February 2024
sdfType values are intended to be registered to enable modeling
additional SDF-specific types (see Section 4.7.1).
The registration policy is Specification Required as per Section 4.6
of [BCP26]. The instructions to the Expert are to ascertain that the
specification provides enough detail to enable interoperability
between implementations of the sdfType being registered, and that
names are chosen with enough specificity that ecosystem-specific
sdfTypes will not be confused with more generally applicable ones.
The initial set of registrations is described in Table 13.
+=============+=============+========+================+============+
| Name | Description | type | JSON | Reference |
| | | | Representation | |
+=============+=============+========+================+============+
| byte-string | A sequence | string | base64url | Section |
| | of zero or | | without | 3.4.5.2 of |
| | more bytes | | padding | [RFC8949] |
+-------------+-------------+--------+----------------+------------+
| unix-time | A point in | number | POSIX time | Section |
| | civil time | | | 3.4.2 of |
| | | | | [RFC8949] |
+-------------+-------------+--------+----------------+------------+
Table 13: Initial set of sdfType values
8. Security Considerations
Some wider security considerations applicable to Things are discussed
in [RFC8576]. Section 5 of [RFC8610] gives an overview over security
considerations that arise when formal description techniques are used
to govern interoperability; analogs of these security considerations
can apply to SDF.
The security considerations of underlying building blocks such as
those detailed in Section 10 of [RFC3629] apply. SDF uses JSON as a
representation language; for a number of cases [RFC8259] indicates
that implementation behavior for certain constructs allowed by the
JSON grammar is unpredictable. Implementations need to be robust
against invalid or unpredictable cases on input, preferably by
rejecting input that is invalid or that would lead to unpredictable
behavior, and need to avoid generating these cases on output.
Implementations of model languages may also exhibit performance-
related availability issues when the attacker can control the input,
see Section 4.1 of [I-D.ietf-jsonpath-base] for a brief discussion.
Koster, et al. Expires 1 September 2024 [Page 45]
Internet-Draft SDF (Semantic Definition Format) February 2024
SDF may be used in two processes that are often security relevant:
model-based _validation_ of data that is intended to be described by
SDF models, and model-based _augmentation_ of these data with
information obtained from the SDF models that apply.
Implementations need to ascertain the provenance and applicability of
the SDF models they employ operationally in such security relevant
ways. Implementations that make use of the composition mechanisms
defined in this document need to do this for each of the components
they combine into the SDF models they employ. Essentially, this
process needs to undergo the same care and scrutiny as any other
introduction of source code into a build environment; the possibility
of supply-chain attacks on the modules imported needs to be
considered.
Specifically, implementations might rely on model-based input
validation for enforcing certain properties of the data structure
ingested (which, if not validated, could lead to malfunctions such as
crashes and remote code execution). These implementations need to be
particularly careful about the data models they apply, including
their provenance and potential changes of these properties that
upgrades to the referenced modules may (inadvertently or as part of
an attack) cause. More generally speaking, implementations should
strive to be robust against expected and unexpected limitations of
the model-based input validation mechanisms and their
implementations.
Similarly, implementations that rely on model-based augmentation may
generate false data from their inputs; this is an integrity violation
in any case but also can possibly be exploited for further attacks.
In applications that dynamically acquire models and obtain modules
from module references in these, the security considerations of
dereferenceable identifiers apply (see [I-D.bormann-t2trg-deref-id]
for a more extensive discussion of dereferenceable identifiers).
There may be confidentiality requirements on SDF models, both on
their content and on the fact that a specific model is used in a
particular Thing or environment. The present specification does not
discuss model discovery or define an access control model for SDF
models, nor does it define a way to obtain selective disclosure where
that may be required. It is likely that these definitions require
additional context from underlying ecosystems and the characteristics
of the protocols employed there; this is therefore left as future
work (e.g., for documents such as [I-D.bormann-asdf-sdf-mapping]).
9. References
Koster, et al. Expires 1 September 2024 [Page 46]
Internet-Draft SDF (Semantic Definition Format) February 2024
9.1. Normative References
[BCP26] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>.
[IANA.params]
IANA, "Uniform Resource Name (URN) Namespace for IETF
Use", <https://www.iana.org/assignments/params>.
[IANA.senml]
IANA, "Sensor Measurement Lists (SenML)",
<https://www.iana.org/assignments/senml>.
[RFC0020] Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969,
<https://www.rfc-editor.org/rfc/rfc20>.
[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>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/rfc/rfc3339>.
[RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
2003, <https://www.rfc-editor.org/rfc/rfc3553>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/rfc/rfc3629>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/rfc/rfc4122>.
Koster, et al. Expires 1 September 2024 [Page 47]
Internet-Draft SDF (Semantic Definition Format) February 2024
[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>.
[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>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/rfc/rfc8259>.
[RFC8428] Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C.
Bormann, "Sensor Measurement Lists (SenML)", RFC 8428,
DOI 10.17487/RFC8428, August 2018,
<https://www.rfc-editor.org/rfc/rfc8428>.
[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>.
[RFC8798] Bormann, C., "Additional Units for Sensor Measurement
Lists (SenML)", RFC 8798, DOI 10.17487/RFC8798, June 2020,
<https://www.rfc-editor.org/rfc/rfc8798>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/rfc/rfc8949>.
[RFC9165] Bormann, C., "Additional Control Operators for the Concise
Data Definition Language (CDDL)", RFC 9165,
DOI 10.17487/RFC9165, December 2021,
<https://www.rfc-editor.org/rfc/rfc9165>.
[RFC9193] Keränen, A. and C. Bormann, "Sensor Measurement Lists
(SenML) Fields for Indicating Data Value Content-Format",
RFC 9193, DOI 10.17487/RFC9193, June 2022,
<https://www.rfc-editor.org/rfc/rfc9193>.
Koster, et al. Expires 1 September 2024 [Page 48]
Internet-Draft SDF (Semantic Definition Format) February 2024
[SPDX] "SPDX License List", <https://spdx.org/licenses/>.
[W3C.NOTE-curie-20101216]
Birbeck, M., Ed. and S. McCarron, Ed., "CURIE Syntax 1.0",
W3C NOTE NOTE-curie-20101216, W3C NOTE-curie-20101216, 16
December 2010,
<https://www.w3.org/TR/2010/NOTE-curie-20101216/>.
9.2. Informative References
[CamelCase]
"Camel Case", December 2014,
<http://wiki.c2.com/?CamelCase>.
[ECMA-262] Ecma International, "ECMAScript 2020 Language
Specification", ECMA Standard ECMA-262, 11th Edition, June
2020, <https://www.ecma-international.org/wp-
content/uploads/ECMA-262.pdf>.
[I-D.bormann-asdf-sdf-mapping]
Bormann, C. and J. Romann, "Semantic Definition Format
(SDF): Mapping files", Work in Progress, Internet-Draft,
draft-bormann-asdf-sdf-mapping-03, 3 December 2023,
<https://datatracker.ietf.org/doc/html/draft-bormann-asdf-
sdf-mapping-03>.
[I-D.bormann-asdf-sdftype-link]
Bormann, C., "An sdfType for Links", Work in Progress,
Internet-Draft, draft-bormann-asdf-sdftype-link-02, 3
December 2023, <https://datatracker.ietf.org/doc/html/
draft-bormann-asdf-sdftype-link-02>.
[I-D.bormann-t2trg-deref-id]
Bormann, C. and C. Amsüss, "The "dereferenceable
identifier" pattern", Work in Progress, Internet-Draft,
draft-bormann-t2trg-deref-id-02, 19 December 2023,
<https://datatracker.ietf.org/doc/html/draft-bormann-
t2trg-deref-id-02>.
[I-D.ietf-jsonpath-base]
Gössner, S., Normington, G., and C. Bormann, "JSONPath:
Query expressions for JSON", Work in Progress, Internet-
Draft, draft-ietf-jsonpath-base-21, 24 September 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-
jsonpath-base-21>.
Koster, et al. Expires 1 September 2024 [Page 49]
Internet-Draft SDF (Semantic Definition Format) February 2024
[I-D.irtf-t2trg-rest-iot]
Keränen, A., Kovatsch, M., and K. Hartke, "Guidance on
RESTful Design for Internet of Things Systems", Work in
Progress, Internet-Draft, draft-irtf-t2trg-rest-iot-13, 25
January 2024, <https://datatracker.ietf.org/doc/html/
draft-irtf-t2trg-rest-iot-13>.
[JSO4] Galiegue, F., Zyp, K., and G. Court, "JSON Schema: core
definitions and terminology", Work in Progress, Internet-
Draft, draft-zyp-json-schema-04, 31 January 2013,
<https://datatracker.ietf.org/doc/html/draft-zyp-json-
schema-04>. This is the base specification for json-
schema.org "draft 4".
[JSO4V] Zyp, K. and G. Court, "JSON Schema: interactive and non
interactive validation", Work in Progress, Internet-Draft,
draft-fge-json-schema-validation-00, 31 January 2013,
<https://datatracker.ietf.org/doc/html/draft-fge-json-
schema-validation-00>. This is the validation
specification for json-schema.org "draft 4".
[JSO7] Wright, A. and H. Andrews, "JSON Schema: A Media Type for
Describing JSON Documents", Work in Progress, Internet-
Draft, draft-handrews-json-schema-01, 19 March 2018,
<https://datatracker.ietf.org/doc/html/draft-handrews-
json-schema-01>. This is the base specification for json-
schema.org "draft 7".
[JSO7V] Wright, A., Andrews, H., and G. Luff, "JSON Schema
Validation: A Vocabulary for Structural Validation of
JSON", Work in Progress, Internet-Draft, draft-handrews-
json-schema-validation-01, 19 March 2018,
<https://datatracker.ietf.org/doc/html/draft-handrews-
json-schema-validation-01>. This is the validation
specification for json-schema.org "draft 7".
[KebabCase]
"Kebab Case", August 2014,
<http://wiki.c2.com/?KebabCase>.
[OCF] "OCF Resource Type Specification",
<https://openconnectivity.org/specs/
OCF_Resource_Type_Specification.pdf>.
[OMA] "OMA LightweightM2M (LwM2M) Object and Resource Registry",
<http://www.openmobilealliance.org/wp/omna/lwm2m/
lwm2mregistry.html>.
Koster, et al. Expires 1 September 2024 [Page 50]
Internet-Draft SDF (Semantic Definition Format) February 2024
[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>.
[RFC9485] Bormann, C. and T. Bray, "I-Regexp: An Interoperable
Regular Expression Format", RFC 9485,
DOI 10.17487/RFC9485, October 2023,
<https://www.rfc-editor.org/rfc/rfc9485>.
[ZCL] "The ZigBee Cluster Library", Elsevier, Zigbee Wireless
Networking pp. 239-271,
DOI 10.1016/b978-0-7506-8597-9.00006-9, 2008,
<https://doi.org/10.1016/b978-0-7506-8597-9.00006-9>.
Appendix A. Formal Syntax of SDF
This appendix describes the syntax of SDF using CDDL [RFC8610].
This appendix shows the framework syntax only, i.e., a syntax with
liberal extension points. Since this syntax is nearly useless in
finding typos in an SDF specification, a second syntax, the
validation syntax, is defined that does not include the extension
points. The validation syntax can be generated from the framework
syntax by leaving out all lines containing the string EXTENSION-
POINT; as this is trivial, the result is not shown here.
This appendix makes use of CDDL "features" as defined in Section 4 of
[RFC9165]. Features whose names end in "-ext" indicate extension
points for further evolution.
start = sdf-syntax
sdf-syntax = {
; info will be required in most process policies
? info: sdfinfo
? namespace: named<text>
? defaultNamespace: text
; Thing is a composition of objects that work together in some way
? sdfThing: named<thingqualities>
; Object is a set of Properties, Actions, and Events that together
; perform a particular function
? sdfObject: named<objectqualities>
; Includes Properties, Actions, and Events as well as sdfData
paedataqualities
EXTENSION-POINT<"top-ext">
}
Koster, et al. Expires 1 September 2024 [Page 51]
Internet-Draft SDF (Semantic Definition Format) February 2024
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]*"
sdf-pointer = global / same-object / true
global = text .regexp ".*[:#].*" ; rough CURIE or JSON Pointer syntax
same-object = referenceable-name
referenceable-name = text .regexp "[^:#]*"
; per se no point in having an empty list, but used for sdfRequired
; in odmobject-multiple_axis_joystick.sdf.json
pointer-list = [* sdf-pointer]
optional-comment = (
? $comment: text ; source code comments only, no semantics
)
commonqualities = (
? description: text ; long text (no constraints)
? label: text ; short text (no constraints); default to key
optional-comment
? sdfRef: sdf-pointer
; applies to qualities of properties, of data:
? sdfRequired: pointer-list
)
arraydefinitionqualities = (
? "minItems" => uint
? "maxItems" => uint
)
Koster, et al. Expires 1 September 2024 [Page 52]
Internet-Draft SDF (Semantic Definition Format) February 2024
paedataqualities = (
; Property represents the state of an instance of an object
? sdfProperty: named<propertyqualities>
; Action invokes an application layer verb associated with an object
? sdfAction: named<actionqualities>
; Event represents an occurrence of event associated with an object
? sdfEvent: named<eventqualities>
; Data represents a piece of information that can be the state of a
; property or a parameter to an action or a signal in an event
? sdfData: named<dataqualities>
)
; for building hierarchy
thingqualities = {
commonqualities
? sdfObject: named<objectqualities>
? sdfThing: named<thingqualities>
paedataqualities
arraydefinitionqualities
EXTENSION-POINT<"thing-ext">
}
; for single objects, or for arrays of objects
objectqualities = {
commonqualities
paedataqualities
arraydefinitionqualities
EXTENSION-POINT<"object-ext">
}
parameter-list = dataqualities
actionqualities = {
commonqualities
? sdfInputData: parameter-list ; sdfRequiredInputData applies here
? sdfOutputData: parameter-list ; sdfRequired applies here
; zero or more named data type definitions that might be used above
? sdfData: named<dataqualities>
EXTENSION-POINT<"action-ext">
}
eventqualities = {
commonqualities
? sdfOutputData: parameter-list ; sdfRequired applies here
; zero or more named data type definitions that might be used above
? sdfData: named<dataqualities>
EXTENSION-POINT<"event-ext">
Koster, et al. Expires 1 September 2024 [Page 53]
Internet-Draft SDF (Semantic Definition Format) February 2024
}
sdftype-name = text .regexp "[a-z][-a-z0-9]*" ; EXTENSION-POINT
dataqualities = {
commonqualities
jsonschema
? "unit" => text
? nullable: bool
? "sdfType" => "byte-string" / "unix-time"
/ (sdftype-name .feature "sdftype-ext") ; EXTENSION-POINT
? contentFormat: text
EXTENSION-POINT<"data-ext">
}
propertyqualities = {
? observable: bool
? readable: bool
? writable: bool
~dataqualities
}
allowed-types = number / text / bool / null
/ [* number] / [* text] / [* bool]
/ {* text => any}
/ (any .feature "allowed-ext") ; EXTENSION-POINT
compound-type = (
"type" => "object"
? required: [+text]
? properties: named<dataqualities>
)
optional-choice = (
? (("sdfChoice" => named<dataqualities>)
// ("enum" => [+ text])) ; limited to text strings
)
jsonschema = (
? (("type" => "number" / "string" / "boolean" / "integer" / "array")
// compound-type
// (type: text .feature "type-ext") ; EXTENSION-POINT
)
; if present, all other qualities apply to all choices:
optional-choice
; the next three should validate against type:
? const: allowed-types
? default: allowed-types
Koster, et al. Expires 1 September 2024 [Page 54]
Internet-Draft SDF (Semantic Definition Format) February 2024
; number/integer constraints
? minimum: number
? maximum: number
? exclusiveMinimum: number
? exclusiveMaximum: number
? multipleOf: number
; text string constraints
? minLength: uint
? maxLength: uint
? pattern: text ; regexp
? format: "date-time" / "date" / "time"
/ "uri" / "uri-reference" / "uuid"
/ (text .feature "format-ext") ; EXTENSION-POINT
; array constraints
? minItems: uint
? maxItems: uint
? uniqueItems: bool
? items: jso-items
)
jso-items = {
? sdfRef: sdf-pointer ; import limited to subset allowed here...
? description: text ; long text (no constraints)
optional-comment
; leave commonqualities out for non-complex data types,
; but need the above three.
; no further nesting: no "array"
? ((type: "number" / "string" / "boolean" / "integer")
// compound-type
// (type: text .feature "itemtype-ext") ; EXTENSION-POINT
)
; if present, all other qualities apply to all choices
optional-choice
; jso subset
? minimum: number
? maximum: number
? format: text
? minLength: uint
? maxLength: uint
EXTENSION-POINT<"items-ext">
}
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
Koster, et al. Expires 1 September 2024 [Page 55]
Internet-Draft SDF (Semantic Definition Format) February 2024
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
; 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"]
'
Appendix B. json-schema.org Rendition of SDF Syntax
This appendix describes the syntax of SDF defined in Appendix A, but
using a version of the description techniques advertised on json-
schema.org [JSO7] [JSO7V].
The appendix shows both the validation and the framework syntax.
Since most of the lines are the same between these two files, those
lines are shown only once, with a leading space, in the form of a
unified diff. Lines leading with a - are part of the validation
syntax, and lines leading with a + are part of the framework syntax.
{
- "title": "sdf-validation.cddl -- Generated: 2024-02-29T07:42:35Z",
+ "title": "sdf-framework.cddl -- Generated: 2024-02-29T07:42:52Z",
"$schema": "http://json-schema.org/draft-07/schema#",
"$ref": "#/definitions/sdf-syntax",
"definitions": {
"sdf-syntax": {
"type": "object",
"properties": {
"info": {
"$ref": "#/definitions/sdfinfo"
},
"namespace": {
"type": "object",
"additionalProperties": {
"type": "string"
}
},
"defaultNamespace": {
Koster, et al. Expires 1 September 2024 [Page 56]
Internet-Draft SDF (Semantic Definition Format) February 2024
"type": "string"
},
"sdfThing": {
"type": "object",
"additionalProperties": {
"$ref": "#/definitions/thingqualities"
}
},
"sdfObject": {
"type": "object",
"additionalProperties": {
"$ref": "#/definitions/objectqualities"
}
},
"sdfProperty": {
"$ref": "#/definitions/sdfProperty-"
},
"sdfAction": {
"$ref": "#/definitions/sdfAction-"
},
"sdfEvent": {
"$ref": "#/definitions/sdfEvent-"
},
"sdfData": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
}
},
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"additionalProperties": false
},
"sdfinfo": {
"type": "object",
"properties": {
"title": {
"type": "string"
},
"description": {
"type": "string"
},
"version": {
"type": "string"
},
"copyright": {
"type": "string"
},
Koster, et al. Expires 1 September 2024 [Page 57]
Internet-Draft SDF (Semantic Definition Format) February 2024
"license": {
"type": "string"
},
"modified": {
"$ref": "#/definitions/modified-date-time"
},
"features": {
- "type": "array",
- "maxItems": 0
+ "type": "array"
},
"$comment": {
"type": "string"
}
},
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"additionalProperties": false
},
"modified-date-time": {
"type": "string"
},
"thingqualities": {
"type": "object",
"properties": {
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"sdfObject": {
"type": "object",
"additionalProperties": {
"$ref": "#/definitions/objectqualities"
}
},
Koster, et al. Expires 1 September 2024 [Page 58]
Internet-Draft SDF (Semantic Definition Format) February 2024
"sdfThing": {
"type": "object",
"additionalProperties": {
"$ref": "#/definitions/thingqualities"
}
},
"sdfProperty": {
"$ref": "#/definitions/sdfProperty-"
},
"sdfAction": {
"$ref": "#/definitions/sdfAction-"
},
"sdfEvent": {
"$ref": "#/definitions/sdfEvent-"
},
"sdfData": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
}
},
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"additionalProperties": false
},
"sdf-pointer": {
"anyOf": [
{
"$ref": "#/definitions/global"
},
{
"$ref": "#/definitions/same-object"
},
{
"$ref": "#/definitions/true"
}
]
},
"global": {
"type": "string",
"pattern": "^[^\\n\\r]*[:#][^\\n\\r]*$"
},
Koster, et al. Expires 1 September 2024 [Page 59]
Internet-Draft SDF (Semantic Definition Format) February 2024
"same-object": {
"$ref": "#/definitions/referenceable-name"
},
"referenceable-name": {
"type": "string",
"pattern": "^[^:#]*$"
},
"true": {
"type": "boolean",
"const": true
},
"pointer-list": {
"type": "array",
"items": {
"$ref": "#/definitions/sdf-pointer"
}
},
"objectqualities": {
"type": "object",
"properties": {
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"sdfProperty": {
"$ref": "#/definitions/sdfProperty-"
},
"sdfAction": {
"$ref": "#/definitions/sdfAction-"
},
"sdfEvent": {
"$ref": "#/definitions/sdfEvent-"
},
"sdfData": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"minItems": {
Koster, et al. Expires 1 September 2024 [Page 60]
Internet-Draft SDF (Semantic Definition Format) February 2024
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
}
},
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"additionalProperties": false
},
"propertyqualities": {
"anyOf": [
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
"$ref": "#/definitions/type-"
},
"sdfChoice": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"observable": {
"type": "boolean"
},
"readable": {
"type": "boolean"
},
"writable": {
"type": "boolean"
},
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
Koster, et al. Expires 1 September 2024 [Page 61]
Internet-Draft SDF (Semantic Definition Format) February 2024
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"exclusiveMinimum": {
"type": "number"
},
"exclusiveMaximum": {
"type": "number"
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
},
Koster, et al. Expires 1 September 2024 [Page 62]
Internet-Draft SDF (Semantic Definition Format) February 2024
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
},
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
+ "properties": {
+ "type": {
+ "type": "string",
+ "const": "object"
+ },
+ "required": {
+ "type": "array",
+ "items": {
+ "type": "string"
+ },
+ "minItems": 1
+ },
+ "properties": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
+ },
+ "sdfChoice": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
+ },
+ "observable": {
+ "type": "boolean"
+ },
+ "readable": {
+ "type": "boolean"
+ },
+ "writable": {
+ "type": "boolean"
+ },
Koster, et al. Expires 1 September 2024 [Page 63]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ "description": {
+ "type": "string"
+ },
+ "label": {
+ "type": "string"
+ },
+ "$comment": {
+ "type": "string"
+ },
+ "sdfRef": {
+ "$ref": "#/definitions/sdf-pointer"
+ },
+ "sdfRequired": {
+ "$ref": "#/definitions/pointer-list"
+ },
+ "const": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "default": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "minimum": {
+ "type": "number"
+ },
+ "maximum": {
+ "type": "number"
+ },
+ "exclusiveMinimum": {
+ "type": "number"
+ },
+ "exclusiveMaximum": {
+ "type": "number"
+ },
+ "multipleOf": {
+ "type": "number"
+ },
+ "minLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "pattern": {
+ "type": "string"
+ },
+ "format": {
+ "$ref": "#/definitions/format-"
+ },
Koster, et al. Expires 1 September 2024 [Page 64]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ "minItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "uniqueItems": {
+ "type": "boolean"
+ },
+ "items": {
+ "$ref": "#/definitions/jso-items"
+ },
+ "unit": {
+ "type": "string"
+ },
+ "nullable": {
+ "type": "boolean"
+ },
+ "sdfType": {
+ "$ref": "#/definitions/sdfType-"
+ },
+ "contentFormat": {
+ "type": "string"
+ }
+ },
+ "additionalProperties": false
+ },
+ {
+ "type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
+ "properties": {
+ "type": {
+ "type": "string"
+ },
+ "sdfChoice": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
+ },
+ "observable": {
+ "type": "boolean"
+ },
+ "readable": {
+ "type": "boolean"
+ },
+ "writable": {
+ "type": "boolean"
Koster, et al. Expires 1 September 2024 [Page 65]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ },
+ "description": {
+ "type": "string"
+ },
+ "label": {
+ "type": "string"
+ },
+ "$comment": {
+ "type": "string"
+ },
+ "sdfRef": {
+ "$ref": "#/definitions/sdf-pointer"
+ },
+ "sdfRequired": {
+ "$ref": "#/definitions/pointer-list"
+ },
+ "const": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "default": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "minimum": {
+ "type": "number"
+ },
+ "maximum": {
+ "type": "number"
+ },
+ "exclusiveMinimum": {
+ "type": "number"
+ },
+ "exclusiveMaximum": {
+ "type": "number"
+ },
+ "multipleOf": {
+ "type": "number"
+ },
+ "minLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "pattern": {
+ "type": "string"
+ },
+ "format": {
+ "$ref": "#/definitions/format-"
Koster, et al. Expires 1 September 2024 [Page 66]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ },
+ "minItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "uniqueItems": {
+ "type": "boolean"
+ },
+ "items": {
+ "$ref": "#/definitions/jso-items"
+ },
+ "unit": {
+ "type": "string"
+ },
+ "nullable": {
+ "type": "boolean"
+ },
+ "sdfType": {
+ "$ref": "#/definitions/sdfType-"
+ },
+ "contentFormat": {
+ "type": "string"
+ }
+ },
+ "additionalProperties": false
+ },
+ {
+ "type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
+ "properties": {
+ "type": {
+ "$ref": "#/definitions/type-"
+ },
+ "enum": {
+ "type": "array",
+ "items": {
+ "type": "string"
+ },
+ "minItems": 1
+ },
+ "observable": {
+ "type": "boolean"
+ },
Koster, et al. Expires 1 September 2024 [Page 67]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ "readable": {
+ "type": "boolean"
+ },
+ "writable": {
+ "type": "boolean"
+ },
+ "description": {
+ "type": "string"
+ },
+ "label": {
+ "type": "string"
+ },
+ "$comment": {
+ "type": "string"
+ },
+ "sdfRef": {
+ "$ref": "#/definitions/sdf-pointer"
+ },
+ "sdfRequired": {
+ "$ref": "#/definitions/pointer-list"
+ },
+ "const": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "default": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "minimum": {
+ "type": "number"
+ },
+ "maximum": {
+ "type": "number"
+ },
+ "exclusiveMinimum": {
+ "type": "number"
+ },
+ "exclusiveMaximum": {
+ "type": "number"
+ },
+ "multipleOf": {
+ "type": "number"
+ },
+ "minLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxLength": {
+ "$ref": "#/definitions/uint"
+ },
Koster, et al. Expires 1 September 2024 [Page 68]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ "pattern": {
+ "type": "string"
+ },
+ "format": {
+ "$ref": "#/definitions/format-"
+ },
+ "minItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "uniqueItems": {
+ "type": "boolean"
+ },
+ "items": {
+ "$ref": "#/definitions/jso-items"
+ },
+ "unit": {
+ "type": "string"
+ },
+ "nullable": {
+ "type": "boolean"
+ },
+ "sdfType": {
+ "$ref": "#/definitions/sdfType-"
+ },
+ "contentFormat": {
+ "type": "string"
+ }
+ },
+ "additionalProperties": false
+ },
+ {
+ "type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
+ "properties": {
+ "type": {
+ "type": "string",
+ "const": "object"
+ },
+ "required": {
+ "type": "array",
+ "items": {
+ "type": "string"
Koster, et al. Expires 1 September 2024 [Page 69]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ },
+ "minItems": 1
+ },
+ "properties": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
+ },
+ "enum": {
+ "type": "array",
+ "items": {
+ "type": "string"
+ },
+ "minItems": 1
+ },
+ "observable": {
+ "type": "boolean"
+ },
+ "readable": {
+ "type": "boolean"
+ },
+ "writable": {
+ "type": "boolean"
+ },
+ "description": {
+ "type": "string"
+ },
+ "label": {
+ "type": "string"
+ },
+ "$comment": {
+ "type": "string"
+ },
+ "sdfRef": {
+ "$ref": "#/definitions/sdf-pointer"
+ },
+ "sdfRequired": {
+ "$ref": "#/definitions/pointer-list"
+ },
+ "const": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "default": {
+ "$ref": "#/definitions/allowed-types"
+ },
+ "minimum": {
+ "type": "number"
+ },
+ "maximum": {
+ "type": "number"
Koster, et al. Expires 1 September 2024 [Page 70]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ },
+ "exclusiveMinimum": {
+ "type": "number"
+ },
+ "exclusiveMaximum": {
+ "type": "number"
+ },
+ "multipleOf": {
+ "type": "number"
+ },
+ "minLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "pattern": {
+ "type": "string"
+ },
+ "format": {
+ "$ref": "#/definitions/format-"
+ },
+ "minItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxItems": {
+ "$ref": "#/definitions/uint"
+ },
+ "uniqueItems": {
+ "type": "boolean"
+ },
+ "items": {
+ "$ref": "#/definitions/jso-items"
+ },
+ "unit": {
+ "type": "string"
+ },
+ "nullable": {
+ "type": "boolean"
+ },
+ "sdfType": {
+ "$ref": "#/definitions/sdfType-"
+ },
+ "contentFormat": {
+ "type": "string"
+ }
+ },
+ "additionalProperties": false
Koster, et al. Expires 1 September 2024 [Page 71]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ },
+ {
+ "type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
- "type": "string",
- "const": "object"
+ "type": "string"
},
- "required": {
+ "enum": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
- "properties": {
- "$ref": "#/definitions/sdfData-sdfChoice-properties-"
- },
- "sdfChoice": {
- "$ref": "#/definitions/sdfData-sdfChoice-properties-"
- },
"observable": {
"type": "boolean"
},
"readable": {
"type": "boolean"
},
"writable": {
"type": "boolean"
},
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
Koster, et al. Expires 1 September 2024 [Page 72]
Internet-Draft SDF (Semantic Definition Format) February 2024
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"exclusiveMinimum": {
"type": "number"
},
"exclusiveMaximum": {
"type": "number"
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
},
Koster, et al. Expires 1 September 2024 [Page 73]
Internet-Draft SDF (Semantic Definition Format) February 2024
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
- },
+ }
+ ]
+ },
+ "dataqualities": {
+ "anyOf": [
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
"$ref": "#/definitions/type-"
},
- "enum": {
- "type": "array",
- "items": {
- "type": "string"
- },
- "minItems": 1
- },
- "observable": {
- "type": "boolean"
- },
- "readable": {
- "type": "boolean"
- },
- "writable": {
- "type": "boolean"
+ "sdfChoice": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
Koster, et al. Expires 1 September 2024 [Page 74]
Internet-Draft SDF (Semantic Definition Format) February 2024
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"exclusiveMinimum": {
"type": "number"
},
"exclusiveMaximum": {
"type": "number"
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
Koster, et al. Expires 1 September 2024 [Page 75]
Internet-Draft SDF (Semantic Definition Format) February 2024
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
},
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
},
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
"type": "string",
"const": "object"
},
"required": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
"properties": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
Koster, et al. Expires 1 September 2024 [Page 76]
Internet-Draft SDF (Semantic Definition Format) February 2024
- "enum": {
- "type": "array",
- "items": {
- "type": "string"
- },
- "minItems": 1
- },
- "observable": {
- "type": "boolean"
- },
- "readable": {
- "type": "boolean"
- },
- "writable": {
- "type": "boolean"
+ "sdfChoice": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"exclusiveMinimum": {
"type": "number"
},
Koster, et al. Expires 1 September 2024 [Page 77]
Internet-Draft SDF (Semantic Definition Format) February 2024
"exclusiveMaximum": {
"type": "number"
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
},
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
- }
- ]
- },
- "dataqualities": {
Koster, et al. Expires 1 September 2024 [Page 78]
Internet-Draft SDF (Semantic Definition Format) February 2024
- "anyOf": [
+ },
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
- "$ref": "#/definitions/type-"
+ "type": "string"
},
"sdfChoice": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"exclusiveMinimum": {
"type": "number"
},
"exclusiveMaximum": {
"type": "number"
Koster, et al. Expires 1 September 2024 [Page 79]
Internet-Draft SDF (Semantic Definition Format) February 2024
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
},
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
},
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
Koster, et al. Expires 1 September 2024 [Page 80]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ },
"properties": {
"type": {
- "type": "string",
- "const": "object"
+ "$ref": "#/definitions/type-"
},
- "required": {
+ "enum": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
- "properties": {
- "$ref": "#/definitions/sdfData-sdfChoice-properties-"
- },
- "sdfChoice": {
- "$ref": "#/definitions/sdfData-sdfChoice-properties-"
- },
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
Koster, et al. Expires 1 September 2024 [Page 81]
Internet-Draft SDF (Semantic Definition Format) February 2024
"exclusiveMinimum": {
"type": "number"
},
"exclusiveMaximum": {
"type": "number"
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
},
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
},
Koster, et al. Expires 1 September 2024 [Page 82]
Internet-Draft SDF (Semantic Definition Format) February 2024
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
- "$ref": "#/definitions/type-"
+ "type": "string",
+ "const": "object"
+ },
+ "required": {
+ "type": "array",
+ "items": {
+ "type": "string"
+ },
+ "minItems": 1
+ },
+ "properties": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"enum": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
Koster, et al. Expires 1 September 2024 [Page 83]
Internet-Draft SDF (Semantic Definition Format) February 2024
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"exclusiveMinimum": {
"type": "number"
},
"exclusiveMaximum": {
"type": "number"
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
},
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
Koster, et al. Expires 1 September 2024 [Page 84]
Internet-Draft SDF (Semantic Definition Format) February 2024
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
},
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
- "type": "string",
- "const": "object"
- },
- "required": {
- "type": "array",
- "items": {
- "type": "string"
- },
- "minItems": 1
- },
- "properties": {
- "$ref": "#/definitions/sdfData-sdfChoice-properties-"
+ "type": "string"
},
"enum": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
Koster, et al. Expires 1 September 2024 [Page 85]
Internet-Draft SDF (Semantic Definition Format) February 2024
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"const": {
"$ref": "#/definitions/allowed-types"
},
"default": {
"$ref": "#/definitions/allowed-types"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"exclusiveMinimum": {
"type": "number"
},
"exclusiveMaximum": {
"type": "number"
},
"multipleOf": {
"type": "number"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
},
"pattern": {
"type": "string"
},
"format": {
"$ref": "#/definitions/format-"
},
"minItems": {
"$ref": "#/definitions/uint"
},
"maxItems": {
"$ref": "#/definitions/uint"
},
"uniqueItems": {
"type": "boolean"
},
"items": {
"$ref": "#/definitions/jso-items"
Koster, et al. Expires 1 September 2024 [Page 86]
Internet-Draft SDF (Semantic Definition Format) February 2024
},
"unit": {
"type": "string"
},
"nullable": {
"type": "boolean"
},
"sdfType": {
"$ref": "#/definitions/sdfType-"
},
"contentFormat": {
"type": "string"
}
},
"additionalProperties": false
}
]
},
"allowed-types": {
"anyOf": [
{
"type": "number"
},
{
"type": "string"
},
{
"type": "boolean"
},
{
"type": "null"
},
{
"type": "array",
"items": {
"type": "number"
}
},
{
"type": "array",
"items": {
"type": "string"
}
},
{
"type": "array",
"items": {
"type": "boolean"
Koster, et al. Expires 1 September 2024 [Page 87]
Internet-Draft SDF (Semantic Definition Format) February 2024
}
},
{
"type": "object",
"additionalProperties": {
}
+ },
+ {
}
]
},
"uint": {
"type": "integer",
"minimum": 0
},
"jso-items": {
"anyOf": [
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
"type": "string",
"enum": [
"number",
"string",
"boolean",
"integer"
]
},
"sdfChoice": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"description": {
"type": "string"
},
"$comment": {
"type": "string"
},
"minimum": {
"type": "number"
},
Koster, et al. Expires 1 September 2024 [Page 88]
Internet-Draft SDF (Semantic Definition Format) February 2024
"maximum": {
"type": "number"
},
"format": {
"type": "string"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
}
},
"additionalProperties": false
},
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
"type": "string",
"const": "object"
},
"required": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
"properties": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"sdfChoice": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"description": {
"type": "string"
},
"$comment": {
"type": "string"
},
Koster, et al. Expires 1 September 2024 [Page 89]
Internet-Draft SDF (Semantic Definition Format) February 2024
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"format": {
"type": "string"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
}
},
"additionalProperties": false
},
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
+ "properties": {
+ "type": {
+ "type": "string"
+ },
+ "sdfChoice": {
+ "$ref": "#/definitions/sdfData-sdfChoice-properties-"
+ },
+ "sdfRef": {
+ "$ref": "#/definitions/sdf-pointer"
+ },
+ "description": {
+ "type": "string"
+ },
+ "$comment": {
+ "type": "string"
+ },
+ "minimum": {
+ "type": "number"
+ },
+ "maximum": {
+ "type": "number"
+ },
+ "format": {
+ "type": "string"
Koster, et al. Expires 1 September 2024 [Page 90]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ },
+ "minLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxLength": {
+ "$ref": "#/definitions/uint"
+ }
+ },
+ "additionalProperties": false
+ },
+ {
+ "type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
"type": "string",
"enum": [
"number",
"string",
"boolean",
"integer"
]
},
"enum": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"description": {
"type": "string"
},
"$comment": {
"type": "string"
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
Koster, et al. Expires 1 September 2024 [Page 91]
Internet-Draft SDF (Semantic Definition Format) February 2024
"format": {
"type": "string"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
}
},
"additionalProperties": false
},
{
"type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"properties": {
"type": {
"type": "string",
"const": "object"
},
"required": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
"properties": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
},
"enum": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"description": {
"type": "string"
},
"$comment": {
"type": "string"
Koster, et al. Expires 1 September 2024 [Page 92]
Internet-Draft SDF (Semantic Definition Format) February 2024
},
"minimum": {
"type": "number"
},
"maximum": {
"type": "number"
},
"format": {
"type": "string"
},
"minLength": {
"$ref": "#/definitions/uint"
},
"maxLength": {
"$ref": "#/definitions/uint"
}
},
"additionalProperties": false
+ },
+ {
+ "type": "object",
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
+ "properties": {
+ "type": {
+ "type": "string"
+ },
+ "enum": {
+ "type": "array",
+ "items": {
+ "type": "string"
+ },
+ "minItems": 1
+ },
+ "sdfRef": {
+ "$ref": "#/definitions/sdf-pointer"
+ },
+ "description": {
+ "type": "string"
+ },
+ "$comment": {
+ "type": "string"
+ },
+ "minimum": {
+ "type": "number"
+ },
Koster, et al. Expires 1 September 2024 [Page 93]
Internet-Draft SDF (Semantic Definition Format) February 2024
+ "maximum": {
+ "type": "number"
+ },
+ "format": {
+ "type": "string"
+ },
+ "minLength": {
+ "$ref": "#/definitions/uint"
+ },
+ "maxLength": {
+ "$ref": "#/definitions/uint"
+ }
+ },
+ "additionalProperties": false
}
]
},
+ "sdftype-name": {
+ "type": "string",
+ "pattern": "^[a-z][\\-a-z0-9]*$"
+ },
"actionqualities": {
"type": "object",
"properties": {
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"sdfInputData": {
"$ref": "#/definitions/parameter-list"
},
"sdfOutputData": {
"$ref": "#/definitions/parameter-list"
},
"sdfData": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
}
Koster, et al. Expires 1 September 2024 [Page 94]
Internet-Draft SDF (Semantic Definition Format) February 2024
},
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"additionalProperties": false
},
"parameter-list": {
"$ref": "#/definitions/dataqualities"
},
"eventqualities": {
"type": "object",
"properties": {
"description": {
"type": "string"
},
"label": {
"type": "string"
},
"$comment": {
"type": "string"
},
"sdfRef": {
"$ref": "#/definitions/sdf-pointer"
},
"sdfRequired": {
"$ref": "#/definitions/pointer-list"
},
"sdfOutputData": {
"$ref": "#/definitions/parameter-list"
},
"sdfData": {
"$ref": "#/definitions/sdfData-sdfChoice-properties-"
}
},
+ "patternProperties": {
+ "^(?:[a-z][a-z0-9]*:)?[a-z$][A-Za-z$0-9]*$": {
+ }
+ },
"additionalProperties": false
},
"format-": {
- "type": "string",
- "enum": [
- "date-time",
- "date",
- "time",
- "uri",
Koster, et al. Expires 1 September 2024 [Page 95]
Internet-Draft SDF (Semantic Definition Format) February 2024
- "uri-reference",
- "uuid"
+ "anyOf": [
+ {
+ "type": "string",
+ "const": "date-time"
+ },
+ {
+ "type": "string",
+ "const": "date"
+ },
+ {
+ "type": "string",
+ "const": "time"
+ },
+ {
+ "type": "string",
+ "const": "uri"
+ },
+ {
+ "type": "string",
+ "const": "uri-reference"
+ },
+ {
+ "type": "string",
+ "const": "uuid"
+ },
+ {
+ "type": "string"
+ }
+ ]
+ },
+ "sdfType-": {
+ "anyOf": [
+ {
+ "type": "string",
+ "const": "byte-string"
+ },
+ {
+ "type": "string",
+ "const": "unix-time"
+ },
+ {
+ "$ref": "#/definitions/sdftype-name"
+ }
]
},
"sdfData-sdfChoice-properties-": {
Koster, et al. Expires 1 September 2024 [Page 96]
Internet-Draft SDF (Semantic Definition Format) February 2024
"type": "object",
"additionalProperties": {
"$ref": "#/definitions/dataqualities"
}
},
"type-": {
"type": "string",
"enum": [
"number",
"string",
"boolean",
"integer",
"array"
]
},
- "sdfAction-": {
+ "sdfEvent-": {
"type": "object",
"additionalProperties": {
- "$ref": "#/definitions/actionqualities"
+ "$ref": "#/definitions/eventqualities"
}
},
- "sdfProperty-": {
+ "sdfAction-": {
"type": "object",
"additionalProperties": {
- "$ref": "#/definitions/propertyqualities"
+ "$ref": "#/definitions/actionqualities"
}
},
- "sdfEvent-": {
+ "sdfProperty-": {
"type": "object",
"additionalProperties": {
- "$ref": "#/definitions/eventqualities"
+ "$ref": "#/definitions/propertyqualities"
}
- },
- "sdfType-": {
- "type": "string",
- "enum": [
- "byte-string",
- "unix-time"
- ]
}
}
}
Koster, et al. Expires 1 September 2024 [Page 97]
Internet-Draft SDF (Semantic Definition Format) February 2024
Appendix C. Data Qualities inspired by json-schema.org
Data qualities define data used in SDF affordances at an information
model level. A popular way to describe JSON data at a data model
level is proposed by a number of drafts on json-schema.org (which
collectively are abbreviated JSO here); for reference to a popular
version we will point here to [JSO7] and [JSO7V]. As the vocabulary
used by JSO is familiar to many JSON modelers, the present
specification borrows some of the terms and ports their semantics to
the information model level needed for SDF.
The main data quality imported is the "type". In SDF, this can take
one of six (text string) values, which are discussed in the following
subsections (note that the JSO type "null" is not supported as a
value of this data quality in SDF).
The additional quality "const" restricts the data to one specific
value (given as the value of the const quality).
Similarly, the additional quality "default" provides data that can be
used in the absence of the data (given as the value of the const
quality); this is mainly documentary and not very well-defined for
SDF as no process is defined that would add default values to an
instance of some interaction data.
C.1. type "number", type "integer"
The types "number" and "integer" are associated with floating point
and integer numbers, as they are available in JSON. A type value of
integer means that only integer values of JSON numbers can be used
(note that 10.0 is an integer value, even if it is in a notation that
would also allow non-zero decimal fractions).
The additional data qualities "minimum", "maximum",
"exclusiveMinimum", "exclusiveMaximum" provide number values that
serve as inclusive/exclusive lower/upper bounds for the number.
(Note that the Boolean form of "exclusiveMinimum"/"exclusiveMaximum"
found in earlier JSO drafts [JSO4V] is not used.)
The data quality "multipleOf" gives a positive number that constrains
the data value to be an integer multiple of the number given. (Type
"integer" can also be expressed as a "multipleOf" quality of value 1,
unless another "multipleOf" quality is present.)
C.2. type "string"
The type "string" is associated with Unicode text string values as
they can be represented in JSON.
Koster, et al. Expires 1 September 2024 [Page 98]
Internet-Draft SDF (Semantic Definition Format) February 2024
The length (as measured in characters) can be constrained by the
additional data qualities "minLength" and "maxLength", which are
inclusive bounds.
(More specifically, Unicode text strings as defined in this
specification are sequences of Unicode scalar values, the number of
which is taken as the length of such a text string. Note that
earlier drafts of this specification explained text string length
values in bytes, which however is not meaningful unless bound to a
specific encoding — which could be UTF-8, if this unusual behavior is
to be provided in an extension.)
The data quality "pattern" takes a string value that is interpreted
as an [ECMA-262] regular expression in Unicode mode that constrains
the string (note that these are not anchored by default, so unless ^
and $ anchors are employed, ECMA-262 regular expressions match any
string that _contains_ a match). The JSO proposals acknowledge that
regular expression support is rather diverse in various platforms, so
the suggestion is to limit them to:
* characters;
* character classes in square brackets, including ranges; their
complements;
* simple quantifiers *, +, ?, and range quantifiers {n}, {n,m}, and
{n,};
* grouping parentheses;
* the choice operator |;
* and anchors (beginning-of-input ^ and end-of-input $).
Note that this subset is somewhat similar to the subset introduced by
I-Regexps [RFC9485], which however are anchored regular expressions,
and which include certain backslash escapes for characters and
character classes.
The additional data quality "format" can take one of the following
values. Note that, at an information model level, the presence of
this data quality changes the type from being a simple text string to
the abstract meaning of the format given (i.e., the format "date-
time" is less about the specific syntax employed in [RFC3339] than
about the usage as an absolute point in civil time).
* "date-time", "date", "time": An [RFC3339] date-time, full-date, or
full-time, respectively.
* "uri", "uri-reference": An [RFC3986] URI or URI Reference,
respectively.
* "uuid": An [RFC4122] UUID.
Koster, et al. Expires 1 September 2024 [Page 99]
Internet-Draft SDF (Semantic Definition Format) February 2024
C.3. type "boolean"
The type "boolean" can take the values "true" or "false".
C.4. type "array"
The type "array" is associated with arrays as they are available in
JSON.
The additional quality "items" gives the type that each of the
elements of the array must match.
The number of elements in the array can be constrained by the
additional data qualities "minItems" and "maxItems", which are
inclusive bounds.
The additional data quality "uniqueItems" gives a Boolean value that,
if true, requires the elements to be all different.
C.5. type "object"
The type "object" is associated with maps, from strings to values, as
they are available in JSON.
The additional quality "properties" is a map the entries of which
describe entries in the specified JSON map: The key gives an
allowable map key for the specified JSON map, and the value is a map
with a named set of data qualities giving the type for the
corresponding value in the specified JSON map.
All entries specified this way are optional, unless they are listed
in the value of the additional quality "required", which is an array
of string values that give the key names of required entries.
Note that the term "properties" as an additional quality for defining
map entries is unrelated to sdfProperty.
C.6. Implementation notes
JSO-based keywords are also used in the specification techniques of a
number of ecosystems, but some adjustments may be required.
Koster, et al. Expires 1 September 2024 [Page 100]
Internet-Draft SDF (Semantic Definition Format) February 2024
For instance, [OCF] is based on Swagger 2.0 which appears to be based
on "draft-4" [JSO4][JSO4V] (also called draft-5, but semantically
intended to be equivalent to draft-4). The "exclusiveMinimum" and
"exclusiveMaximum" keywords use the Boolean form there, so on import
to SDF their values have to be replaced by the values of the
respective "minimum"/"maximum" keyword, which are themselves then
removed; the reverse transformation applies on export.
Appendix D. Composition Examples
This appendix contains two examples illustrating different
composition approaches using the sdfThing quality.
D.1. Outlet Strip Example
{
"sdfThing": {
"outlet-strip": {
"label": "Outlet strip",
"description": "Contains a number of Sockets",
"sdfObject": {
"socket": {
"description": "An array of sockets in the outlet strip",
"minItems": 2,
"maxItems": 10
}
}
}
}
}
Figure 6
D.2. Refrigerator-Freezer Example
Koster, et al. Expires 1 September 2024 [Page 101]
Internet-Draft SDF (Semantic Definition Format) February 2024
{
"sdfThing": {
"refrigerator-freezer": {
"description": "A refrigerator combined with a freezer",
"sdfProperty": {
"status": {
"type": "boolean",
"description":
"Indicates if the refrigerator-freezer is powered"
}
},
"sdfObject": {
"refrigerator": {
"description": "A refrigerator compartment",
"sdfProperty": {
"temperature": {
"sdfRef": "#/sdfProproperty/temperature",
"maximum": 8
}
}
},
"freezer": {
"label": "A freezer compartment",
"sdfProperty": {
"temperature": {
"sdfRef": "#/sdfProproperty/temperature",
"maximum": -6
}
}
}
}
}
},
"sdfProperty": {
"temperature": {
"description": "The temperature for this compartment",
"type": "number",
"unit": "Cel"
}
}
}
Figure 7
Acknowledgements
This specification is based on work by the One Data Model group.
Koster, et al. Expires 1 September 2024 [Page 102]
Internet-Draft SDF (Semantic Definition Format) February 2024
Contributors
Jan Romann
Universität Bremen
Email: jan.romann@uni-bremen.de
Wouter van der Beek
Cascoda Ltd.
Threefield House
Threefield Lane
Southampton
United Kingdom
Email: w.vanderbeek@cascoda.com
Authors' Addresses
Michael Koster (editor)
KTC
29415 Alderpoint Road
Blocksburg, CA, 95514
United States of America
Phone: +1-707-502-5136
Email: michaeljohnkoster@gmail.com
Carsten Bormann (editor)
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Ari Keränen
Ericsson
FI-02420 Jorvas
Finland
Email: ari.keranen@ericsson.com
Koster, et al. Expires 1 September 2024 [Page 103]
