A Link-Format Attribute for Locating Things

This memo proposes a new CoAP link-format attribute, "geo", that can be used to associate positioning metadata to a CoAP resource, and make this information available to other endpoints that, directly or indirectly, participate in to CoAP link-format discovery . The ability for a consuming application to access positioning information about a sensing resource is crucial in a number of use cases, especially those in which one or more sensor networks provide input to an emergency handling service (e.g. fire, flood, etc.). This spec reuses the geo URI syntax , which is capable to describe physical locations in two or three dimensions (also supporting underground and underwater localisation using negative numbers) in a compact, simple and human readable way.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in .

Location-aware applications and location-based services like seismic networks, gas pipeline monitoring deployments, fire or flood detection systems, etc., need to precisely locate the source of sensed stimulus in order to react in a sensible way. {TODO collect other use cases}

This section defines a new Web Linking link-param, "geo", to be used within the framework, having the following syntax:

The geo attribute MUST NOT appear more than once in a link. (NOTE about Link-Format queries: non exact matches cannot be easily/effectively queried.)

A fire detector somewhere in the Pollino National Park (approx. 10cm accuracy, enough to distinguish trees from each other):

;ct=0;if="sensor;geo="40.00201,16.34007" ]]> An underwater current sampler in the sea between Ithaki and Kefallonia (approx. 10m accuracy):

;ct=0;if="sensor;geo="38.2953,20.6426,-20" ]]>

See Section 3.5. of .

TODO

The "geo" link-format attributes share the same security issues as any other attribute involved in the discovery process described in . Further to that, the privacy considerations regarding distribution, protection, usage, retention, and storage of the location information of the target resource found in fully apply.