WIP: Common constraints - identifiers #271
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@@ -956,6 +956,56 @@ <h2>Default Language</h2> | |
| (e.g., en, de-AT, gsw-CH, zh-Hans, zh-Hant-HK, sl-nedis).</span> | ||
| </span> | ||
| </section> | ||
| <section id="sec-identifiers"> | ||
| <h2>Identifiers</h2> | ||
| <p> | ||
| Web resources are identified by uniform resource identifiers (URIs). | ||
| The Thing Description defines the field <a href="https://w3c.github.io/wot-thing-description/#thing><code>id</code></a> | ||
| for that purpose, which is in the format "anyURI". | ||
| </p> | ||
| <p> | ||
| In deployments of multiple devices in the same application context, things must be distinguished by the consumer. | ||
| In these cases, these identifiers must be <em>unique</em>. | ||
| Use cases with worldwide deployments typically require <em>globally</em> unique identifiers. | ||
| </p> | ||
| <section id="sec-identifiers-format"> | ||
| <h3>Format</h3> | ||
| <p> | ||
| A common and well defined format for these identifiers enables easy implementation | ||
| and simplifies handling across manufacturers through the use of libraries. | ||
| It also ensures that there are no name clashes of devices from different manufacturers. | ||
| The [[UUID]] format has been developed to satisfy these requirements. | ||
| </p> | ||
| <p> | ||
| <span class="rfc2119-assertion" id="common-constraints-identifiers-uuid"> | ||
| It is RECOMMENDED to use Universally Unique IDentifier (UUID) [[RFC4122]] as common format for identifers. | ||
| </span> | ||
| </p> | ||
| <span class="rfc2119-assertion" id="common-constraints-identifiers-random"> | ||
| It is RECOMMENDED to use [[UUIDv4]] as common format for unique identifers, where random identifiers are required. | ||
| </span> | ||
| </p> | ||
| </section> | ||
| <section id="sec-identifiers-mutability"> | ||
| <h3>Mutable and Immutable Identifiers</h3> | ||
| <p> | ||
| Many use cases require that identifiers do not change during the lifecycle of the thing in the application context. | ||
| However there are cases, where the IDs must change due to legal or privacy obligations. | ||
| IDs should be changed when a device is offboarded and onboarded on a new system (e.g. for change | ||
| of ownership). | ||
| In these cases, or when a device is moved to a new usage context, identifiers usually must change. | ||
| </p> | ||
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| <p><span class="rfc2119-assertion" id="common-constraints-identifiers-mutable"> | ||
| In certain use cases where privacy is a factor or legal obligations mandate changing identifiers, | ||
| the use of a <em>mutable UUID</em> is RECOMMENDED.</span> | ||
| </p> | ||
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| <p><span class="rfc2119-assertion" id="common-constraints-identifiers-immutable-ids"> | ||
| If possible and allowed by law, required immutable IDs SHOULD be made available through a | ||
| property rather than used as the id for the TD itself. | ||
| </span></p> | ||
| </section> | ||
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There was a problem hiding this comment. This is already covered in section 11.2 Immutable Identifiers of TD 1.1. I don't think this text really adds anything to that text. There was a problem hiding this comment. This goes beyond what the TD describes in section 11.2. The proposed text talks specifically about UUIDs, i.e. a format this is well-defined, whereas the TD does not have any format description for identifiers. |
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| </section> | ||
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I'm pleased to see that this is only a recommendation, however:
In WebThings we still use the URL of the Thing Description as its ID, which has many benefits.
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The URL is not stable in scenarios where things may transition between different networks. Think of roaming scenarios in fleet management, IP reassignment cases etc.