idnits 2.17.1 draft-ietf-netmod-geo-location-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (November 4, 2019) is 1635 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'EGM08' -- Possible downref: Non-RFC (?) normative reference: ref. 'EGM96' -- Possible downref: Non-RFC (?) normative reference: ref. 'WGS84' Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group C. Hopps 3 Internet-Draft LabN Consulting, L.L.C. 4 Intended status: Standards Track November 4, 2019 5 Expires: May 7, 2020 7 YANG Geo Location 8 draft-ietf-netmod-geo-location-02 10 Abstract 12 This document defines a generic geographical location object YANG 13 grouping. The geographical location grouping is intended to be used 14 in YANG models for specifying a location on or in reference to the 15 Earth or any other astronomical object. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at https://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on May 7, 2020. 34 Copyright Notice 36 Copyright (c) 2019 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (https://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 53 2. The Geo Location Object . . . . . . . . . . . . . . . . . . . 3 54 2.1. Frame of Reference . . . . . . . . . . . . . . . . . . . 3 55 2.2. Location . . . . . . . . . . . . . . . . . . . . . . . . 4 56 2.3. Motion . . . . . . . . . . . . . . . . . . . . . . . . . 4 57 2.4. Nested Locations . . . . . . . . . . . . . . . . . . . . 5 58 2.5. Non-location Attributes . . . . . . . . . . . . . . . . . 5 59 2.6. Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 5 60 3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 6 61 4. ISO 6709:2008 Conformance . . . . . . . . . . . . . . . . . . 11 62 5. Usability . . . . . . . . . . . . . . . . . . . . . . . . . . 12 63 5.1. Portability . . . . . . . . . . . . . . . . . . . . . . . 13 64 5.1.1. IETF URI Value . . . . . . . . . . . . . . . . . . . 13 65 5.1.2. W3C . . . . . . . . . . . . . . . . . . . . . . . . . 13 66 5.1.3. Geography Markup Language (GML) . . . . . . . . . . . 15 67 5.1.4. KML . . . . . . . . . . . . . . . . . . . . . . . . . 15 68 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 69 6.1. Geodetic System Value Registry . . . . . . . . . . . . . 16 70 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17 71 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 72 8.1. Normative References . . . . . . . . . . . . . . . . . . 18 73 8.2. Informative References . . . . . . . . . . . . . . . . . 19 74 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 19 75 Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 22 76 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 23 78 1. Introduction 80 In many applications we would like to specify the location of 81 something geographically. Some examples of locations in networking 82 might be the location of data center, a rack in an internet exchange 83 point, a router, a firewall, a port on some device, or it could be 84 the endpoints of a fiber, or perhaps the failure point along a fiber. 86 Additionally, while this location is typically relative to The Earth, 87 it does not need to be. Indeed it is easy to imagine a network or 88 device located on The Moon, on Mars, on Enceladus (the moon of 89 Saturn) or even a comet (e.g., 67p/churyumov-gerasimenko). 91 Finally, one can imagine defining locations using different frames of 92 reference or even alternate systems (e.g., simulations or virtual 93 realities). 95 This document defines a "geo-location" YANG grouping that allows for 96 all of the above data to be captured. 98 This specification conforms to [ISO.6709.2008]. 100 The YANG data model described in this document conforms to the 101 Network Management Datastore Architecture defined in [RFC8342]. 103 1.1. Terminology 105 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 106 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 107 "OPTIONAL" in this document are to be interpreted as described in 108 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, 109 as shown here. 111 2. The Geo Location Object 113 2.1. Frame of Reference 115 The frame of reference ("reference-frame") defines what the location 116 values refer to and their meaning. The referred to object can be any 117 astronomical body. It could be a planet such as The Earth or Mars, a 118 moon such as Enceladus, an asteroid such as Ceres, or even a comet 119 such as 1P/Halley. This value is specified in "astronomical-body" 120 and is defined by the International Astronomical Union 121 (), The default "astronomical-body" value is 122 "earth". 124 In addition to identifying the astronomical body we also need to 125 define the meaning of the coordinates (e.g., latitude and longitude) 126 and the definition of 0-height. This is done with a "geodetic-datum" 127 value. The default value for "geodetic-datum" is "wgs-84" (i.e., the 128 World Geodetic System, [WGS84]), which is used by the Global 129 Positioning System (GPS) among many others. We define an IANA 130 registry for specifying standard values for the "geodetic-datum". 132 In addition to the "geodetic-datum" value we allow refining the 133 coordinate and height accuracy using "coord-accuracy" and "height- 134 accuracy" respectively. When specified these values override the 135 defaults implied by the "geodetic-datum" value. 137 Finally, we define an optional feature which allows for changing the 138 system for which the above values are defined. This optional feature 139 adds an "alternate-system" value to the reference frame. This value 140 is normally not present which implies the natural universe is the 141 system. The use of this value is intended to allow for creating 142 virtual realities or perhaps alternate coordinate systems. The 143 definition of alternate systems is outside the scope of this 144 document. 146 2.2. Location 148 This is the location on or relative to the astronomical object. It 149 is specified using 2 or 3 coordinates values. These values are given 150 either as "latitude", "longitude", and an optional "height", or as 151 Cartesian coordinates of "x", "y" and an optional "z". For the 152 standard location choice "latitude" and "longitude" are specified as 153 fractions of decimal degrees, and the "height" value is in fractions 154 of meters. For the Cartesian choice "x", "y" and "z" are in 155 fractions of meters. In both choices the exact meanings of all of 156 the values are defined by the "geodetic-datum" value in the 157 Section 2.1. 159 2.3. Motion 161 Support is added for objects in relatively stable motion. For 162 objects in relatively stable motion the grouping provides a 163 3-dimensional vector value. The components of the vector are 164 "v-north", "v-east" and "v-up" which are all given in fractional 165 meters per second. The values "v-north" and "v-east" are relative to 166 true-north as defined by the reference frame for the astronomical 167 body, "v-up" is perpendicular to the plane defined by "v-north" and 168 "v-east", and is pointed away from the center of mass. 170 To derive the 2-dimensional heading and speed one would use the 171 following formulas: 173 ,------------------------------ 174 speed = V v_{north}^{2} + v_{east}^{2} 176 heading = arctan(v_{east} / v_{north}) 178 For some applications that demand high accuracy, and where the data 179 is infrequently updated this velocity vector can track very slow 180 movement such as continental drift. 182 Tracking more complex forms of motion is outside the scope of this 183 work. The intent of the grouping being defined here is to identify 184 where something is located, and generally this is expected to be 185 somewhere on or relative to the Earth (or another astronomical body). 186 At least two options are available to YANG models that wish to use 187 this grouping with objects that are changing location frequently in 188 non-simple ways, they can add additional motion data to their model 189 directly, or if the application allows it can require more frequent 190 queries to keep the location data current. 192 2.4. Nested Locations 194 When locations are nested (e.g., a building may have a location which 195 houses routers that also have locations) the module using this 196 grouping is free to indicate in its definition that the "reference- 197 frame" is inherited from the containing object so that the 198 "reference-frame" need not be repeated in every instance of location 199 data. 201 2.5. Non-location Attributes 203 During the development of this module, the question of whether it 204 would support data such as orientation arose. These types of 205 attributes are outside the scope of this grouping because they do not 206 deal with a location but rather describe something more about the 207 object that is at the location. Module authors are free to add these 208 non-location attributes along with their use of this location 209 grouping. 211 2.6. Tree 213 The following is the YANG tree diagram [RFC8340] for the geo-location 214 grouping. 216 module: ietf-geo-location 217 grouping geo-location 218 +-- geo-location 219 +-- reference-frame 220 | +-- alternate-system? string {alternate-systems}? 221 | +-- astronomical-body? string 222 | +-- geodetic-system 223 | +-- geodetic-datum? string 224 | +-- coord-accuracy? decimal64 225 | +-- height-accuracy? decimal64 226 +-- (location)? 227 | +--:(ellipsoid) 228 | | +-- latitude? degrees 229 | | +-- longitude? degrees 230 | | +-- height? decimal64 231 | +--:(cartesian) 232 | +-- x? decimal64 233 | +-- y? decimal64 234 | +-- z? decimal64 235 +-- velocity 236 | +-- v-north? decimal64 237 | +-- v-east? decimal64 238 | +-- v-up? decimal64 239 +-- timestamp? types:date-and-time 241 Figure 1: Geo Location YANG tree diagram. 243 3. YANG Module 245 file "ietf-geo-location@2019-02-17.yang" 246 module ietf-geo-location { 247 namespace "urn:ietf:params:xml:ns:yang:ietf-geo-location"; 248 prefix geo; 249 import ietf-yang-types { prefix types; } 251 organization 252 "IETF NETMOD Working Group (NETMOD)"; 253 contact 254 "Christian Hopps "; 256 // RFC Ed.: replace XXXX with actual RFC number and 257 // remove this note. 259 description 260 "This module defines a grouping of a container object for 261 specifying a location on or around an astronomical object (e.g., 262 The Earth). 264 Copyright (c) 2019 IETF Trust and the persons identified as 265 authors of the code. All rights reserved. 267 Redistribution and use in source and binary forms, with or 268 without modification, is permitted pursuant to, and subject to 269 the license terms contained in, the Simplified BSD License set 270 forth in Section 4.c of the IETF Trust's Legal Provisions 271 Relating to IETF Documents 272 (https://trustee.ietf.org/license-info). 274 This version of this YANG module is part of RFC XXXX 275 (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself 276 for full legal notices. 278 // RFC Ed.: replace XXXX with actual RFC number and 279 // remove this note. 281 The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL 282 NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED', 283 'MAY', and 'OPTIONAL' in this document are to be interpreted as 284 described in BCP 14 (RFC 2119) (RFC 8174) when, and only when, 285 they appear in all capitals, as shown here."; 287 revision 2019-02-17 { 288 description "Initial Revision"; 289 reference "RFC XXXX: YANG Geo Location"; 290 } 292 typedef degrees { 293 type decimal64 { 294 fraction-digits 16; 295 } 296 units "decimal degrees"; 297 description "Coordinate value."; 298 } 300 feature alternate-systems { 301 description 302 "This feature means the device supports specifying locations 303 using alternate systems for reference frames."; 304 } 306 grouping geo-location { 307 description 308 "Grouping to identify a location on an astronomical object."; 310 container geo-location { 311 description 312 "A location on an astronomical body (e.g., The Earth) 313 somewhere in a universe."; 315 container reference-frame { 316 description 317 "The Frame of Reference for the location values."; 319 leaf alternate-system { 320 if-feature alternate-systems; 321 type string; 322 description 323 "The system in which the astronomical body and 324 geodetic-datum is defined. Normally, this value is not 325 present and the system is the natural universe; however, 326 when present this value allows for specifying alternate 327 systems (e.g., virtual realities). An alternate-system 328 modifies the definition (but not the type) of the other 329 values in the reference frame."; 330 } 331 leaf astronomical-body { 332 type string { 333 pattern '[ -@\[-\^_-~]*'; 334 } 335 default "earth"; 336 description 337 "An astronomical body as named by the International 338 Astronomical Union (IAU) or according to the alternate 339 system if specified. Examples include 'sun' (our star), 340 'earth' (our planet), 'moon' (our moon), 'enceladus' (a 341 moon of Saturn), 'ceres' (an asteroid), 342 '67p/churyumov-gerasimenko (a comet). The value should 343 be comprised of all lower case ASCII characters not 344 including control characters (i.e., values 32..64, and 345 91..126). Any preceding 'the' in the name should not 346 be included."; 347 } 348 container geodetic-system { 349 description 350 "The geodetic system of the location data."; 351 leaf geodetic-datum { 352 type string { 353 pattern '[ -@\[-\^_-~]*'; 354 } 355 default "wgs-84"; 356 description 357 "A geodetic-datum defining the meaning of latitude, 358 longitude and height. The default is 'wgs-84' which is 359 used by the Global Positioning System (GPS). The value 360 SHOULD be comprised of all lower case ASCII characters 361 not including control characters (i.e., values 32..64, 362 and 91..126). The IANA registry further restricts the 363 value by converting all spaces (' ') to dashes ('-')"; 364 } 365 leaf coord-accuracy { 366 type decimal64 { 367 fraction-digits 6; 368 } 369 description 370 "The accuracy of the latitude longitude pair. When 371 coord-accuracy is specified it overrides the 372 geodetic-datum implied accuracy. If Cartesian 373 coordinates are in use this accuracy corresponds to 374 the X and Y components"; 375 } 376 leaf height-accuracy { 377 type decimal64 { 378 fraction-digits 6; 379 } 380 units "meters"; 381 description 382 "The accuracy of height value. When specified it 383 overrides the geodetic-datum implied default. If 384 Cartesian coordinates ar in use this accuracy 385 corresponds to the Z component."; 386 } 387 // May wish to allow for height to be relative. 388 // If so need to decide if we have a boolean (to ground) 389 // or an enumeration (e.g., local ground, sea-floor, 390 // ground floor, containing object, ...) or even allow 391 // for a string for most generic but least portable 392 // comparable 393 // leaf height-relative { 394 // } 395 } 396 } 397 choice location { 398 description 399 "The location data either in lat/long or Cartesian values"; 400 case ellipsoid { 401 leaf latitude { 402 type degrees; 403 description 404 "The latitude value on the astronomical body. The 405 definition and precision of this measurement is 406 indicated by the reference-frame value."; 407 } 408 leaf longitude { 409 type degrees; 410 description 411 "The longitude value on the astronomical body. The 412 definition and precision of this measurement is 413 indicated by the reference-frame."; 414 } 415 leaf height { 416 type decimal64 { 417 fraction-digits 6; 418 } 419 units "meters"; 420 description 421 "Height from a reference 0 value. The precision and '0' 422 value is defined by the reference-frame."; 423 } 424 } 425 case cartesian { 426 leaf x { 427 type decimal64 { 428 fraction-digits 6; 429 } 430 description 431 "The X value as defined by the reference-frame."; 432 } 433 leaf y { 434 type decimal64 { 435 fraction-digits 6; 436 } 437 description 438 "The Y value as defined by the reference-frame."; 439 } 440 leaf z { 441 type decimal64 { 442 fraction-digits 6; 443 } 444 units "meters"; 445 description 446 "The Z value as defined by the reference-frame."; 447 } 448 } 449 } 450 container velocity { 451 description 452 "If the object is in motion the velocity vector describes 453 this motion at the the time given by the timestamp."; 455 leaf v-north { 456 type decimal64 { 457 fraction-digits 12; 458 } 459 units "meters per second"; 460 description 461 "v-north is the rate of change (i.e., speed) towards 462 truth north as defined by the ~geodetic-system~."; 463 } 465 leaf v-east { 466 type decimal64 { 467 fraction-digits 12; 468 } 469 units "meters per second"; 470 description 471 "v-east is the rate of change (i.e., speed) perpendicular 472 to truth-north as defined by the ~geodetic-system~."; 473 } 475 leaf v-up { 476 type decimal64 { 477 fraction-digits 12; 478 } 479 units "meters per second"; 480 description 481 "v-up is the rate of change (i.e., speed) away from the 482 center of mass."; 483 } 484 } 485 leaf timestamp { 486 type types:date-and-time; 487 description "Reference time when location was recorded."; 488 } 489 } 490 } 491 } 492 494 4. ISO 6709:2008 Conformance 496 [ISO.6709.2008] provides an appendix with a set of tests for 497 conformance to the standard. The tests and results are given in the 498 following table along with an explanation of non-applicable tests. 500 +---------+-----------------------------------+---------------------+ 501 | Test | Description | Pass Explanation | 502 +---------+-----------------------------------+---------------------+ 503 | A.1.2.1 | elements reqd. for a geo. point | CRS is always | 504 | | location | indicated | 505 | | | | 506 | A.1.2.2 | Description of a CRS from a | CRS register is | 507 | | register | defined | 508 | | | | 509 | A.1.2.3 | definition of CRS | N/A - Don't define | 510 | | | CRS | 511 | | | | 512 | A.1.2.4 | representation of horizontal | lat/long values | 513 | | position | conform | 514 | | | | 515 | A.1.2.5 | representation of vertical | height value | 516 | | position | conforms | 517 | | | | 518 | A.1.2.6 | text string representation | N/A - No string | 519 | | | format | 520 +---------+-----------------------------------+---------------------+ 522 Conformance Test Results 524 For test "A.1.2.1" the YANG geo location object either includes a CRS 525 ("reference-frame") or has a default defined ([WGS84]). 527 For "A.1.2.3" we do not define our own CRS, and doing so is not 528 required for conformance. 530 For "A.1.2.6" we do not define a text string representation, which is 531 also not required for conformance. 533 5. Usability 535 The geo-location object defined in this document and YANG module have 536 been designed to be usable in a very broad set of applications. This 537 includes the ability to locate things on astronomical bodies other 538 than The Earth, and to utilize entirely different coordinate systems 539 and realities. 541 Many systems make use of geo-location data, and so it's important to 542 be able describe this data using this geo-location object defined in 543 this document. 545 5.1. Portability 547 In order to verify portability while developing this module the 548 following standards and standard APIs and were considered. 550 5.1.1. IETF URI Value 552 [RFC5870] defines a standard URI value for geographic location data. 553 It includes the ability to specify the "geodetic-value" (it calls 554 this "crs") with the default being "wgs-84" [WGS84]. For the 555 location data it allows 2 to 3 coordinates defined by the "crs" 556 value. For accuracy it has a single "u" parameter for specifying 557 uncertainty. The "u" value is in fractions of meters and applies to 558 all the location values. As the URI is a string, all values are 559 specifies as strings and so are capable of as much precision as 560 required. 562 URI values can be mapped to and from the YANG grouping, with the 563 caveat that some loss of precision (in the extremes) may occur due to 564 the YANG grouping using decimal64 values rather than strings. 566 5.1.2. W3C 568 See . 570 W3C Defines a geo-location API in [W3CGEO]. We show a snippet of 571 code below which defines the geo-location data for this API. This is 572 used by many application (e.g., Google Maps API). 574 interface GeolocationPosition { 575 readonly attribute GeolocationCoordinates coords; 576 readonly attribute DOMTimeStamp timestamp; 577 }; 579 interface GeolocationCoordinates { 580 readonly attribute double latitude; 581 readonly attribute double longitude; 582 readonly attribute double? altitude; 583 readonly attribute double accuracy; 584 readonly attribute double? altitudeAccuracy; 586 readonly attribute double? speed; 587 }; 589 Figure 2: Snippet Showing Geo-Location Definition 591 5.1.2.1. Compare with YANG Model 593 +------------------+--------------+-----------------+-------------+ 594 | Field | Type | YANG | Type | 595 +------------------+--------------+-----------------+-------------+ 596 | accuracy | double | coord-accuracy | dec64 fr 6 | 597 | | | | | 598 | altitude | double | height | dec64 fr 6 | 599 | | | | | 600 | altitudeAccuracy | double | height-accuracy | dec64 fr 6 | 601 | | | | | 602 | heading | double | heading | dec64 fr 16 | 603 | | | | | 604 | latitude | double | latitude | dec64 fr 16 | 605 | | | | | 606 | longitude | double | longitude | dec64 fr 16 | 607 | | | | | 608 | speed | double | speed | dec64 fr 12 | 609 | | | | | 610 | timestamp | DOMTimeStamp | timestamp | string | 611 +------------------+--------------+-----------------+-------------+ 613 accuracy (double): 614 Accuracy of "latitude" and "longitude" values in meters. 616 altitude (double): 617 Optional height in meters above the [WGS84] ellipsoid. 619 altitudeAccuracy (double): 620 Optional accuracy of "altitude" value in meters. 622 heading (double): 623 Optional Direction in decimal deg from true north increasing 624 clock-wise. 626 latitude, longitude (double): 627 Standard lat/long values in decimal degrees. 629 speed (double): 630 Speed along heading in meters per second. 632 timestamp (DOMTimeStamp): 633 Specifies milliseconds since the Unix EPOCH in 64 bit unsigned 634 integer. The YANG model defines the timestamp with arbitrarily 635 large precision by using a string which encompasses all 636 representable values of this timestamp value. 638 W3C API values can be mapped to the YANG grouping, with the caveat 639 that some loss of precision (in the extremes) may occur due to the 640 YANG grouping using decimal64 values rather than doubles. 642 Conversely, only YANG values for The Earth using the default "wgs-84" 643 [WGS84] as the "geodetic-datum", can be directly mapped to the W3C 644 values, as W3C does not provide the extra features necessary to map 645 the broader set of values supported by the YANG grouping. 647 5.1.3. Geography Markup Language (GML) 649 ISO adopted the Geography Markup Language (GML) defined by OGC 07-036 650 as [ISO.19136.2007]. GML defines, among many other things, a 651 position type "gml:pos" which is a sequence of "double" values. This 652 sequence of values represent coordinates in a given CRS. The CRS is 653 either inherited from containing elements or directly specified as 654 attributes "srsName" and optionally "srsDimension" on the "gml:pos". 656 GML defines an Abstract CRS type which Concrete CRS types derive 657 from. This allows for many types of CRS definitions. We are 658 concerned with the Geodetic CRS type which can have either 659 ellipsoidal or Cartesian coordinates. We believe that other non- 660 Earth based CRS as well as virtual CRS should also be representable 661 by the GML CRS types as well. 663 Thus GML "gml:pos" values can be mapped directly to the YANG 664 grouping, with the caveat that some loss of precision (in the 665 extremes) may occur due to the YANG grouping using decimal64 values 666 rather than doubles. 668 Conversely, YANG grouping values can be mapped to GML as directly as 669 the GML CRS available definitions allow with a minimum of Earth-based 670 geodetic systems fully supported. 672 GML also defines an observation value in "gml:Observation" which 673 includes a timestamp value "gml:validTime" in addition to other 674 components such as "gml:using" "gml:target" and "gml:resultOf". Only 675 the timestamp is mappable to and from the YANG grouping. Furthermore 676 "gml:validTime" can either be an Instantaneous measure 677 ("gml:TimeInstant") or a time period ("gml:TimePeriod"). Only the 678 instantaneous "gml:TimeInstant" is mappable to and from the YANG 679 grouping. 681 5.1.4. KML 683 KML 2.2 [KML22] (formerly Keyhole Markup Language) was submitted by 684 Google to Open Geospatial Consortium (OGC) 685 and was adopted. The latest 686 version as of this writing is KML 2.3 [KML23]. This schema includes 687 geographic location data in some of it's objects (e.g., objects). This data is provided in string format and 689 corresponds to the [W3CGEO] values. The timestamp value is also 690 specified as a string as in our YANG grouping. 692 KML has some special handling for the height value useful for 693 visualization software, "kml:altitudeMode". These values for 694 "kml:altitudeMode" include indicating the height is ignored 695 ("clampToGround"), in relation to the locations ground level 696 ("relativeToGround"), or in relation to the geodetic datum 697 ("absolute"). The YANG grouping can directly map the ignored and 698 absolute cases, but not the relative to ground case. 700 In addition to the "kml:altitudeMode" KML also defines two seafloor 701 height values using "kml:seaFloorAltitudeMode". One value is to 702 ignore the height value ("clampToSeaFloor") and the other is relative 703 ("relativeToSeaFloor"). As with the "kml:altitudeMode" value, the 704 YANG grouping supports the ignore case but not the relative case. 706 The KML location values use a geodetic datum defined in Annex A by 707 the GML Coordinate Reference System (CRS) [ISO.19136.2007] with 708 identifier "LonLat84_5773". The altitude value for KML absolute 709 height mode is measured from the vertical datum specified by [WGS84]. 711 Thus the YANG grouping and KML values can be directly mapped in both 712 directions (when using a supported altitude mode) with the caveat 713 that some loss of precision (in the extremes) may occur due to the 714 YANG grouping using decimal64 values rather than strings. For the 715 relative height cases the application doing the transformation is 716 expected to have the data available to transform the relative height 717 into an absolute height which can then be expressed using the YANG 718 grouping. 720 6. IANA Considerations 722 6.1. Geodetic System Value Registry 724 This registry allocates names for standard geodetic systems. Often 725 these values are referred to using multiple names (e.g., full names 726 or multiple acronyms values). The intent of this registry is to 727 provide a single standard value for any given geodetic system. 729 The values SHOULD use an acronym when available, they MUST be 730 converted to lower case, and spaces MUST be changed to dashes "-". 732 Each entry should be sufficient to define the 3 coordinate values (2 733 if height is not required). So for example the "wgs-84" is defined 734 as WGS-84 with the geoid updated by at least [EGM96] for height 735 values. Specific entries for [EGM96] and [EGM08] are present if a 736 more precise definition of the data is required. 738 It should be noted that [RFC5870] also creates a registry for 739 Geodetic Systems (it calls CRS); however, this registry has a very 740 strict modification policy. The authors of [RFC5870] have the stated 741 goal of making CRS registration hard to avoid proliferation of CRS 742 values. As our module defines alternate systems and has a broader 743 (beyond earth) scope, the registry defined below is meant to be more 744 easily modified. 746 TODO: Open question, should we create a new registry here or attempt 747 to modify the one created by [RFC5870]. It's worth noting that we 748 include the ability to specify any geodetic system including ones 749 designed for astronomical bodies other than the earth, as well as 750 ones based on alternate systems. These requirements may be too broad 751 for adapting the existing [RFC5870] registry. 753 TODO: Open question, is FCFS too easy, perhaps expert review would 754 strike a good balance. If expert review is acceptable, would it also 755 be acceptable to update the policy on [RFC5870] and use it instead? 757 The allocation policy for this registry is First Come First Served, 758 [RFC8126] as the intent is simply to avoid duplicate values. 760 The initial values for this registry are as follows. 762 +------------+------------------------------------------------------+ 763 | Name | Description | 764 +------------+------------------------------------------------------+ 765 | me | Mean Earth/Polar Axis (Moon) | 766 | | | 767 | mola-vik-1 | MOLA Height, IAU Viking-1 PM (Mars) | 768 | | | 769 | wgs-84-96 | World Geodetic System 1984 [WGS84] w/ EGM96 | 770 | | | 771 | wgs-84-08 | World Geodetic System 1984 [WGS84] w/ [EGM08] | 772 | | | 773 | wgs-84 | World Geodetic System 1984 [WGS84] (EGM96 or better) | 774 +------------+------------------------------------------------------+ 776 7. Security Considerations 778 This document defines a common geo location grouping using the YANG 779 data modeling language. The grouping itself has no security or 780 privacy impact on the Internet, but the usage of the grouping in 781 concrete YANG modules might have. The security considerations 782 spelled out in the YANG 1.1 specification [RFC7950] apply for this 783 document as well. 785 8. References 787 8.1. Normative References 789 [EGM08] Pavlis, N., Holmes, S., Kenyon, S., and J. Factor, "An 790 Earth Gravitational Model to Degree 2160: EGM08.", 2008, 791 . 794 [EGM96] Lemoine, F., Kenyon, S., Factor, J., Trimmer, R., Pavlis, 795 N., Chinn, D., Cox, C., Klosko, S., Luthcke, S., Torrence, 796 M., Wang, Y., Williamson, R., Pavlis, E., Rapp, R., and T. 797 Olson, "The Development of the Joint NASA GSFC and the 798 National Imagery and Mapping Agency (NIMA) Geopotential 799 Model EGM96.", 1998, 800 . 802 [ISO.6709.2008] 803 International Organization for Standardization, "ISO 804 6709:2008 Standard representation of geographic point 805 location by coordinates.", 2008. 807 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 808 Requirement Levels", BCP 14, RFC 2119, 809 DOI 10.17487/RFC2119, March 1997, 810 . 812 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 813 Writing an IANA Considerations Section in RFCs", BCP 26, 814 RFC 8126, DOI 10.17487/RFC8126, June 2017, 815 . 817 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 818 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 819 May 2017, . 821 [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., 822 and R. Wilton, "Network Management Datastore Architecture 823 (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, 824 . 826 [WGS84] National Imagery and Mapping Agency., "National Imagery 827 and Mapping Agency Technical Report 8350.2, Third 828 Edition.", 1 2000, . 831 8.2. Informative References 833 [ISO.19136.2007] 834 International Organization for Standardization, "ISO 835 19136:2007 Geographic information -- Geography Markup 836 Language (GML)". 838 [KML22] Wilson, T., Ed., "OGC KML (Version 2.2)", 4 2008, 839 . 842 [KML23] Burggraf, D., Ed., "OGC KML 2.3", 8 2015, 843 . 846 [RFC5870] Mayrhofer, A. and C. Spanring, "A Uniform Resource 847 Identifier for Geographic Locations ('geo' URI)", 848 RFC 5870, DOI 10.17487/RFC5870, June 2010, 849 . 851 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 852 RFC 7950, DOI 10.17487/RFC7950, August 2016, 853 . 855 [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", 856 BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, 857 . 859 [W3CGEO] Popescu, A., "Geolocation API Specification", 11 2016, 860 . 863 Appendix A. Examples 865 Below is a fictitious module that uses the geo-location grouping. 867 module example-uses-geo-location { 868 namespace 869 "urn:example:example-uses-geo-location"; 870 prefix ugeo; 871 import ietf-geo-location { prefix geo; } 872 organization "Empty Org"; 873 contact "Example Author "; 874 description "Example use of geo-location"; 875 revision 2019-02-02 { reference "None"; } 876 container locatable-items { 877 description "container of locatable items"; 878 list locatable-item { 879 key name; 880 description "A of locatable item"; 881 leaf name { 882 type string; 883 description "name of locatable item"; 884 } 885 uses geo:geo-location; 886 } 887 } 888 } 890 Figure 3: Example YANG module using geo location. 892 Below is a the YANG tree for the fictitious module that uses the geo- 893 location grouping. 895 module: example-uses-geo-location 896 +--rw locatable-items 897 +--rw locatable-item* [name] 898 +--rw name string 899 +--rw geo-location 900 +--rw reference-frame 901 | +--rw alternate-system? string {alternate-systems}? 902 | +--rw astronomical-body? string 903 | +--rw geodetic-system 904 | +--rw geodetic-datum? string 905 | +--rw coord-accuracy? decimal64 906 | +--rw height-accuracy? decimal64 907 +--rw (location)? 908 | +--:(ellipsoid) 909 | | +--rw latitude? degrees 910 | | +--rw longitude? degrees 911 | | +--rw height? decimal64 912 | +--:(cartesian) 913 | +--rw x? decimal64 914 | +--rw y? decimal64 915 | +--rw z? decimal64 916 +--rw velocity 917 | +--rw v-north? decimal64 918 | +--rw v-east? decimal64 919 | +--rw v-up? decimal64 920 +--rw timestamp? types:date-and-time 922 Below is some example YANG XML data for the fictitious module that 923 uses the geo-location grouping. 925 926 927 928 Gaetana's 929 930 40.73297 931 -74.007696 932 933 934 935 Pont des Arts 936 937 2012-03-31T16:00:00Z 938 48.8583424 939 2.3375084 940 35 941 942 943 944 Saint Louis Cathedral 945 946 2013-10-12T15:00:00-06:00 947 29.9579735 948 -90.0637281 949 950 951 952 Apollo 11 Landing Site 953 954 1969-07-21T02:56:15Z 955 956 moon 957 958 me 959 960 961 0.67409 962 23.47298 963 964 965 966 Reference Frame Only 967 968 969 moon 970 971 me 972 973 974 975 976 977 979 Figure 4: Example XML data of geo location use. 981 Appendix B. Acknowledgements 983 We would like to thank Peter Lothberg for the motivation as well as 984 help in defining a more broadly useful geographic location object. 986 We would also like to thank Acee Lindem and Qin Wu for their work on 987 a geographic location object that led to this documents creation. 989 Author's Address 991 Christian Hopps 992 LabN Consulting, L.L.C. 994 Email: chopps@chopps.org