Semantic Definition Format (SDF) Extension for Non-Affordance Information

The Semantic Definition Format (SDF) has been instrumental in standardizing the representation of affordances - properties, actions, and events - of Things . However, there exists a gap in representing non-affordance information, such as location, contextual metadata, and other descriptive elements that do not directly pertain to device interactions. Addressing this gap is crucial for comprehensive device modeling, especially in applications like digital twins where holistic representations are essential. This document describes a framework to extend the SDF by incorporating non-affordance information. Integrating these extensions allows SDF to provide a more comprehensive representation of Things, thereby enhancing semantic descriptions.

Terminology and Conventions 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 when, and only when, they appear in all capitals, as shown here. Non-Affordance: attributes of a Thing that are not directly related to its interactive capabilities. This includes descriptive metadata such as location, manufacturer details, and other contextual information.

The integration of non-affordance information into the Semantic Definition Format (SDF) addresses several critical needs in the modeling of Internet of Things (IoT) devices. The key motivations and corresponding use cases in the following subsections illustrate the importance of this extension:

In the current SDF framework, the primary focus is on defining affordances - interactive elements such as Properties, Actions, and Events. While this approach effectively captures the interactive capabilities of a Thing, it overlooks essential non-interactive attributes that are vital for a comprehensive device representation. These non-affordance attributes encompass contextual information and descriptive metadata, including dimensions, weight, location, manufacturer details, and operational constraints. The absence of standardized representation for such information can lead to fragmented device models, hindering interoperability and the seamless integration of devices across diverse IoT ecosystems.

3.2.1. Asset Management and Tracking Scenario: A logistics company utilizes IoT-enabled containers equipped with sensors to monitor shipments. Requirement: To effectively manage and track these assets, it's crucial to have standardized data on each container's physical dimensions, weight capacity, and current location. Solution: Incorporating non-affordance information into SDF allows for the uniform representation of these attributes, facilitating efficient asset tracking, optimizing load planning, and ensuring compliance with transportation regulations. 3.2.2. Environmental Context Awareness Scenario: A smart building management system integrates various sensors and devices to monitor and control environmental conditions. Requirement: Understanding the installation environment of each device, such as room location, mounting position, and surrounding materials, is essential for accurate data interpretation and optimal system performance. Solution: By extending SDF to include environmental context as non-affordance information, the system can dynamically adjust operations based on device placement and environmental factors, enhancing occupant comfort and energy efficiency. 3.2.3. Regulatory Compliance and Certification Scenario: Medical devices deployed in healthcare facilities must adhere to stringent regulatory standards and certifications. Requirement: Detailed documentation of each device's manufacturer, model number, serial number, and certification information is necessary for compliance audits and maintenance schedules. Solution: Embedding this non-affordance information within SDF ensures that all relevant metadata is consistently available, simplifying compliance reporting and facilitating timely maintenance and recalls when necessary. By integrating non-affordance information into SDF, these use cases demonstrate how a more holistic device model enhances interoperability, operational efficiency, and compliance across various IoT applications.

In the SDF, the primary focus has been on defining affordances - interactive elements such as Properties, Actions, and Events - that specify how external entities can interact with a Thing. However, to achieve a more comprehensive representation of a Thing, it's essential to include non-affordance information, which encompasses attributes not directly related to interaction but crucial for understanding the Thing's context and characteristics. To address this need, we propose introducing a new class named sdfNonAffordance within the SDF architecture. This class allows for the inclusion of metadata such as physical dimensions, location, environmental context, and manufacturer details.

The sdfNonAffordance is defined with attributes such as: name: Identifier for the non-affordance attribute. description: Textual explanation of the attribute. type: Data type (e.g., string, number, object, boolean, array) of the attribute value. unit: Applicable measurement unit, if relevant.

Structure of sdfNonAffordance in SDF { "sdfObject": { "device": { "sdfNonAffordance": { "attribute-name": { "description": "Attribute description", "type": "data type", "unit": "unit if applicable" } } } } } This structure ensures clarity and consistency in representing non-affordance information.

4.3.1. Geospatial information

Example of geospatial information { "sdfObject": { "tracker-device": { "sdfNonAffordance": { "location": { "description": "Geographical coordinates", "type": "object", "wgs84": { "latitude": 60.1676, "longitude": 24.9514 } } } } } } 4.3.2. TBD 4.3.3. TBD

Security Considerations TBD

IANA Considerations TBD