All,

I just posted a first draft of my geolocate extension: https://tools.ietf.org/html/draft-murchison-tzdist-geolocate-00

I switched to using the existing geo URI format for specifying location at the suggestion of one of the authors of TZDIST.  The draft includes an example of doing a query using an uncertainty value.

You can give my test implementation a test drive here:

https://cyrus-test.andrew.cmu.edu/tzdist/zones?location=geo:36.01596,-114.73748;u=25

That server is using Evan Siroky's new shapefiles.  Note that the implementation is not perfect yet as I'm not checking for holes in timezones, nor doing any calculations when a location is in international waters.  Also note that the calculations for finding time zones within an uncertainty range are based on the earth being a sphere (using mean radius), not a spheroid.  I may change this later, but I'm not sure that it matters over short distances.  Finally, there is no data for Antarctica.

All,

(sending to tz@iana.org since tzdist@ietf.org appears to be dead)

I was bored today (actually avoiding "real" work) and was playing around with the ESRI shapefile for timezones

I hacked up a quick extension to my tzdist implementation using the tz_world shapefile and basic ray tracing to be able to query a time zone by geo coordinates, similar to what Google offers in their Time Zone API.  Note that I have yet to spend any time writing code to account for "holes" in time zones like the Navajo Reservation in Arizona.

I modeled the extension after the "find" action in RFC 7808 but with lat/long query params rather than a glob pattern.  A request and response for the timezone in which my home is located looks something like this:


GET /tzdist/zones?latitude=43.070833&longitude=-78.831667 HTTP/1.1

{
  "synctoken": "890939292-1466089793",
  "timezones": [
    {
      "tzid": "America/New_York",
      "etag": "6602582-1466089793",
      "last-modified": "2016-06-16T15:09:53Z",
      "publisher": "IANA Time Zone Database",
      "version": "2016e",
      "aliases": [
        "US/Eastern"
      ]
    }
  ]
}

The definition of the extension looks like this in the capabilities response:

    {
      "name": "geolocate",
      "uri-template": "/zones{?latitude,longitude}",
      "parameters": [
        {
          "name": "latitude",
          "required": true
        },
        {
          "name": "longitude",
          "required": true
        }
      ]
    }

Currently my code only accepts coordinates in decimal degrees, but I think it should probably support ISO 6709 formats.

Is this something that folks would like to see documented as a formal extension to tzdist, either as specified above or with some modification?  If so, I'd be willing to write it up as a draft and then move it through IETF in whatever fashion the ADs recommend.

-- 
Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University

-- 
Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University