<?xml version="1.0" encoding="UTF-8"?>
<rfc version="3" docName="draft-kartha-grd-01" category="info" submissionType="IETF" ipr="trust200902">

  <front>
    <title abbrev="Geospatial Resource Discovery">Geospatial Resource Discovery (GRD): Problem Statement and Conceptual Architecture</title>

    <author fullname="Gokul Sivasankaran Kartha" surname="Kartha" initials="G. S.">
      <organization>Independent</organization>
      <address>
        <email>kartha.gokul@gmail.com</email>
      </address>
    </author>

    <date year="2026" month="January" day="20" />

    <abstract>
      <t>The Internet provides standardized mechanisms for resolving
      identifiers, such as domain names, to network locations. These
      mechanisms assume that a client already knows the identifier of the
      resource it wishes to access. Emerging classes of applications,
      including augmented reality, autonomous systems, robotics, and
      spatial computing, operate under a different assumption. In these
      systems, discovery begins with physical presence and observer context
      rather than with a predefined name.</t>

      <t>This document describes the architectural gap addressed by a
      Geospatial Resource Discovery service. It defines the problem space,
      explains why existing standards are insufficient, and outlines a
      conceptual architecture for spatial discovery. This document is
      informational and architectural in nature. It does not define a
      protocol, data format, or implementation.</t>
    </abstract>
  </front>

  <middle>
    <section title="Introduction">
      <t>Internet architecture has historically focused on resolving semantic
      identifiers into network endpoints. Systems such as the Domain Name
      System enable scalable communication by assuming that clients already
      know the name of the resource they are attempting to reach.</t>

      <t>Emerging spatial systems invert this assumption. In augmented
      reality, autonomous navigation, and smart environments, discovery
      begins with physical location and context. A user or machine
      operating at a specific coordinate needs to ask what digital
      information is associated with the surrounding space and visible
      volume.</t>

      <t>At present, this type of discovery occurs inside closed ecosystems.
      Each platform maintains its own spatial maps, registries, and access
      mechanisms. While effective within individual systems, these
      approaches do not interoperate. This document argues that spatial
      discovery represents a missing architectural layer and describes the
      requirements for an open Geospatial Resource Discovery capability.</t>

      <t>This document is intended to inform future work on interoperable
      spatial discovery mechanisms, potentially including protocol
      specifications.</t>
    </section>

    <section title="Scope and Non-Goals">
      <section title="Scope">
        <t>This document focuses on the application layer. It describes a
        discovery pattern that can operate over existing transports such as
        HTTP/3 or CoAP. It intentionally avoids assumptions about rendering
        engines, device capabilities, or user interface models.</t>
      </section>

      <section title="Non-Goals">
        <t>This document does not propose changes to IP routing or DNS
        semantics. It does not define legal ownership of physical space,
        geometric rendering standards, or a global governance model for
        spatial authority.</t>
      </section>
    </section>

    <section title="Terminology">
      <t>Spatial Resource: A digital asset associated with a physical
      location or volume, such as an augmented reality annotation,
      navigation marker, or machine-readable instruction.</t>

      <t>Spatial Cell: A discrete geospatial region used for indexing and
      lookup, typically derived from a hierarchical grid system.</t>

      <t>Frustum: A three-dimensional volume defined by an observer's
      position, orientation, and field of view.</t>

      <t>Trust Anchor: A cryptographic root of trust (e.g., a Public Key) 
      configured on the client and used to validate data associated with a 
      specific Semantic Layer (e.g., "Safety" or "Transit") within a given 
      context.</t>
    </section>

    <section title="Problem Statement">
      <t>The Internet lacks a standardized mechanism to discover digital
      resources based on physical location and observer context.</t>

      <t>Existing discovery mechanisms resolve names rather than locations.
      While geographic identifiers exist (e.g., <xref target="RFC5870"/>), 
      there is no standard protocol that allows a client to query a location 
      and receive a list of available spatial resources.</t>

      <t>Spatial data is also highly application-specific. Autonomous
      vehicles, wearable devices, and smart infrastructure systems
      operating in the same physical environment cannot discover or consume
      each other's data unless they share a proprietary backend.</t>

      <t>In addition, current application protocols do not natively support
      volumetric queries. Requests such as retrieving resources within a
      three-dimensional viewing volume are not commonly supported in 
      interoperable discovery mechanisms.</t>

      <t>Finally, many spatial resources are dynamic and time-sensitive.
      Real-time spatial information, such as hazards or temporary
      instructions, requires low latency and short validity periods.
      Traditional caching assumptions are poorly suited to these
      constraints.</t>
    </section>

    <section title="Design Guidelines">
      <t>Any future specification for Geospatial Resource Discovery should
      follow a small set of architectural principles. The design should
      remain independent of transport and operate over existing Internet
      protocols. Complex geometric calculations should be performed by the
      client to preserve resolver scalability. Discovery should support
      semantic filtering so that clients can request only relevant
      categories of information. Privacy considerations need to be integral 
      to the design and should limit the precision of location data exposed 
      to discovery services.</t>
    </section>

    <section title="Conceptual Architecture">
      <t>This section outlines a conceptual architecture referred to as
      Geospatial Resource Discovery (GRD).</t>

      <t>The physical world is divided into discrete spatial cells using a
      standard hierarchical indexing system. Representing space in this way
      allows spatial discovery to be reduced to key-based lookups rather
      than continuous geospatial computation.</t>

      <figure anchor="fig_grid" title="Hierarchical Spatial Grid">
        <artwork><![CDATA[
        +---------+---------+---------+
        | Cell A  | Cell B  | Cell C  |
        |         |         |         |
        +---------+---------+---------+
        | Cell D  | Cell E  | Cell F  |
        | (Index) | (Index) | (Index) |
        +---------+---------+---------+
        | Cell G  | Cell H  | Cell I  |
        |         |         |         |
        +---------+---------+---------+
        ]]></artwork>
      </figure>

      <t>A GRD resolver functions as a directory service. The term "resolver" 
      is used descriptively and does not imply a standardized network role. 
      It maintains references to spatial resources indexed by cell identifier 
      and returns pointers to the actual assets. The resolver does not host 
      large content objects such as three-dimensional models.</t>

      <t>Authority over physical space is not strictly hierarchical. Multiple
      independent entities may publish resources associated with the same
      spatial cell. This introduces a fundamental architectural choice
      between client-side aggregation of multiple authorities and resolver-
      side federation of records.</t>

      <t>For example, a federated resolver simplifies client logic and can
      vouch for aggregated data integrity, but requires coordination among
      authorities. Client-side aggregation offers greater autonomy and
      avoids a central point of coordination but places the burden of trust
      evaluation and result merging on each client.</t>
    </section>

    <section title="Volumetric Query Concept">
      <t>To balance scalability and privacy, GRD follows a coarse query and
      fine filter model.</t>

      <t>The client computes its precise view frustum locally and determines
      which standard spatial cells intersect that volume. It then queries
      the resolver for resources associated with those cells, optionally
      filtered by semantic category. This translation from a continuous
      geometric volume to discrete cell identifiers allows spatial
      discovery to leverage standard, cache-friendly HTTP request
      semantics for what is inherently a spatial query.</t>

      <figure anchor="fig_frustum" title="Frustum-to-Cell Intersection">
        <artwork><![CDATA[
                / \
               /   \  <-- View Frustum
              /     \
             /       \
      +-----/---------/-----+
      | Cell X | Cell Y |   |  <-- Client requests Cell X + Y
      +--------+--------+---+      (Standard HTTP GET)
        ]]></artwork>
      </figure>

      <t>The client performs final filtering locally and discards resources
      that fall outside the exact viewing volume. This approach ensures
      that the resolver does not learn the client's precise orientation or
      gaze direction.</t>
    </section>

    <section title="Relationship to Existing Work">
      <section title="IETF Standards">
        <t>RFC 5870 ('geo' URI) defines a method to identify a physical 
        location but does not define a mechanism to retrieve resources 
        associated with that location. GRD complements RFC 5870 by 
        providing the resolution layer.</t>
        
        <t>RFC 9176 (CoRE Resource Directory) enables resource discovery 
        on constrained networks but relies on network endpoints rather 
        than geodetic context. It does not support volumetric or 
        spatial-context queries (e.g., "what is visible from this coordinate").</t>

        <t>RFC 6763 (DNS-SD) is effective for local service discovery via 
        multicast or administrative domains but cannot scale to global, 
        location-based queries required for open spatial computing.</t>
      </section>

      <section title="OGC and GIS Standards">
        <t>OGC standards (e.g., WFS, OGC API - Features) are designed for 
        complex querying of heavy geospatial databases. GRD is designed as 
        a lightweight, low-latency resolution service (conceptually 
        similar to DNS in its indirection role) for real-time spatial 
        computing, handing off the heavy data transfer to 
        application-specific protocols.</t>
      </section>
    </section>

    <section title="Security and Trust Challenges">
      <t>A primary risk in spatial discovery is reality poisoning: the
      injection of false or malicious information that directly alters a
      user's perception of the physical world. The safety implications are
      significant--consider the effect of a counterfeit right-of-way
      marker for an autonomous vehicle or a hallucinated safe path over a
      physical hazard for a first responder.</t>

      <section title="Trust Model">
        <t>GRD cannot rely on a single global root of trust. Instead, trust 
        must be contextual and scoped by semantic layer. A "Safety" layer 
        might rely on a government Trust Anchor, while a "Commercial" layer 
        might rely on a different registry. The architecture is expected 
        to require that Spatial Resource Records (SRRs) carry cryptographic 
        signatures verifiable against the client's configured Trust Anchors 
        for that specific layer.</t>
      </section>
    </section>

    <section title="Privacy Considerations">
      <section title="Attacker Model">
        <t>The GRD Resolver is modeled as an Honest-but-Curious adversary. 
        It is trusted to return correct spatial records but is assumed to 
        log queries in an attempt to reconstruct client trajectories.</t>
      </section>

      <section title="Measurable Privacy Goals">
        <t>Privacy risks are mitigated by enforcing minimum cell granularity 
        (k-anonymity), intended to ensure that a query does not uniquely 
        identify a user within a small physical area. Additionally, the 
        architecture is expected to avoid reliance on persistent session 
        identifiers that allow the Resolver to correlate separate queries 
        to a single device (Unlinkability).</t>
      </section>
    </section>

    <section title="IANA Considerations">
      <t>This document does not request any IANA actions.</t>
    </section>

  </middle>

  <back>
    <references title="References">
      <reference anchor="RFC5870">
        <front>
          <title>A Uniform Resource Identifier for Geographic Locations ('geo' URI)</title>
          <author initials="A." surname="Mayrhofer" fullname="A. Mayrhofer"><organization/></author>
          <author initials="C." surname="Spanring" fullname="C. Spanring"><organization/></author>
          <date year="2010" month="June" />
        </front>
        <seriesInfo name="RFC" value="5870" />
      </reference>

      <reference anchor="RFC9176">
        <front>
          <title>Constrained RESTful Environments (CoRE) Resource Directory</title>
          <author initials="Z." surname="Shelby" fullname="Z. Shelby"><organization/></author>
          <author initials="M." surname="Koster" fullname="M. Koster"><organization/></author>
          <author initials="C." surname="Bormann" fullname="C. Bormann"><organization/></author>
          <date year="2022" month="April" />
        </front>
        <seriesInfo name="RFC" value="9176" />
      </reference>

      <reference anchor="RFC6763">
        <front>
          <title>DNS-Based Service Discovery</title>
          <author initials="S." surname="Cheshire" fullname="S. Cheshire"><organization/></author>
          <author initials="M." surname="Krochmal" fullname="M. Krochmal"><organization/></author>
          <date year="2013" month="February" />
        </front>
        <seriesInfo name="RFC" value="6763" />
      </reference>
    </references>

    <section title="Illustrative Data Model">
      <t>This appendix is non-normative and illustrates the type of data a
      resolution service might return.</t>
      <figure>
        <artwork><![CDATA[
{
  "cell_id": "8928308280fffff",
  "resources": [
    {
      "id": "res-12345",
      "type": "safety.warning",
      "location": { "lat": 52.3, "lon": 4.9, "alt": 10 },
      "layer": "infrastructure",
      "uri": "https://city-assets.example.com/signs/stop.glb",
      "validity_ms": 60000,
      "signature": "ab382...[cryptographic proof]"
    }
  ]
}
        ]]></artwork>
      </figure>
    </section>
  </back>

</rfc>