WG Action: Formed A Semantic Definition Format for Data and Interactions of Things (asdf)

[The IESG <[e-mail]>]

A new IETF WG has been formed in the Applications and Real-Time Area. For
additional information, please contact the Area Directors or the WG Chairs.

A Semantic Definition Format for Data and Interactions of Things (asdf)
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Current status: Proposed WG

Chairs:
  Michael Richardson <[e-mail]>
  Niklas Widell <[e-mail]>

Assigned Area Director:
  Barry Leiba <[e-mail]>

Applications and Real-Time Area Directors:
  Barry Leiba <[e-mail]>
  Murray Kucherawy <[e-mail]>

Mailing list:
  Address: [e-mail]
  To subscribe: https://www.ietf.org/mailman/listinfo/asdf
  Archive: https://mailarchive.ietf.org/arch/browse/asdf/

Group page: https://datatracker.ietf.org/group/asdf/

Charter: https://datatracker.ietf.org/doc/charter-ietf-asdf/

## Background

Data and interaction models of IoT devices today exhibit unneeded diversity
between different industry ecosystem standards development organizations
(SDOs), hindering interoperability across these ecosystems with little
discernible benefit from the diversity. Early 2019, One Data Model (OneDM)
was started to bring several IoT SDOs and IoT device and platform vendors
together under a broad, multi-party liaison agreement, with a goal of
arriving at a common set of data and interaction models that describe IoT
devices. Ideally, for every class of IoT device, there is just a single model
selected/created by the participating organizations, which everyone can adopt.

As a common language for writing down these models, the Semantic Definition
Format (SDF, draft-onedm-t2trg-sdf) was created, which can represent IoT
Things, their composition from reusable Objects, their Interaction
Affordances (Properties, Actions, Events), and the data models relevant to
describe these Affordances.  SDF represents these models in JSON, enabling
re-use of specification formats such as CDDL (RFC8610) and the formats
proposed at json-schema.org and their tooling, for describing both the SDF
format itself and the structure of the data to be modelled in SDF.

By July 2020, some 200 models in SDF format have been contributed by
participating ecosystems; new models are being submitted continually. Version
1.0 of the SDF specification was published on the OneDM github repository and
as an Internet-Draft. OneDM is now focusing on consolidating the body of
submitted models and developing processes for arriving at harmonized models
that span different industry ecosystems in a common way; as expressed at the
IETF 108 ASDF BoF, they look to the IETF for developing SDF 1.0 further into
a high-quality specification.

The IETF also defines the YANG data modelling language (RFC 7950). YANG has a
strong focus on modelling the management interface for network devices, using
a fairly small set of network management protocols, whereas SDF is designed
to span (and transitively unify) many existing interaction models already
present. While data associated with a YANG schema can be serialized to a
variety of wire formats (e.g., XML, JSON, CBOR, and others), the
serialization is driven directly by the structure of the data models defined
in YANG; there is no separate "protocol binding" step as in the use of SDF.

Conversely, SDF does not deal directly with serialization at all, modelling
only the structure and semantics of the data being interchanged, hence
leaving data serialization (and RPC semantics) to other standards, most
likely defined by existing IoT SDOs.

## The ASDF Working Group

The objective of the ASDF working group is to develop SDF into a
standards-track specification for thing interaction and data modelling. In
the process of developing this specification, further functional requirements
that emerge in the usage of SDF for model harmonization will be addressed.

The ASDF WG will work with experts from OneDM and its contributing
organizations. In the IETF, it will work closely with the CBOR WG, home of
the CDDL specification.  It will also engage the still active mailing list of
the concluded JSON WG.  Recent proposals to form an IRTF formal description
techniques (FDT) Research Group might lead to another collaboration partner. 
ASDF will work with Thing-to-Thing Research Group (T2TRG) and its WISHI (Work
on IoT Semantic/Hypermedia Interoperability, http://wishi.space) program to
engage researchers and other SDOs in this space, such as W3C Web of Things,
which is working on Thing Models and related specifications.

Milestones:

  Oct 2020 - SDF specification, WG document adopted

  Sep 2021 - SDF specification, publication requested