vCard – the first spec to use “geo:”?

The first specification that is using the “geo:” scheme seems to be the revision of the vCard format. vCards are “virtual business cards”, and contain a multitude of contact information about a person or an organization.

vCard GEO property

The geographic location of a person’s office is of course one of those properties – even the original specification of vCard (RFC 2426) contained an “GEO” property (defined in Section 3.4.2). That property has a range of shortcomings:

• There’s no way to specify altitude
• the Coordinate Reference System is not defined (see here [PDF] why you should care)
• Recommends to always use six decimal places (roughly one meter) rather than allowing for uncertainty values

New revision of vCard includes “geo:” URI

The current revision of the vCard specification (currently worked on in the IETF’s VCARDDAV working group) has changed the format of the “GEO” property. The new definition requires a URI rather than the lat/lon tupel as value, and notes in an example that the “geo:” URI scheme is “particularly well-suited”, although other URI schemes are allowed too. A example vCard using the “geo:” URI looks like this (edited for brevity):

BEGIN:VCARD
VERSION:4.0
FN:Simon Perreault
...
GEO;TYPE=work:geo:46.772673,-71.282945
...
CLASS:PUBLIC
END:VCARD

As outlined above, the structure of vCards allows to supply parameters for properties – in the example above, the GEO property is specified for the “work” location of the contact.

vCard applications become geo: aware

The integration of the URI scheme into the very popular vCard format means that very likely future revisions of vCard applications will be able to parse and use “geo:” URIs. Looking at the list of applications that support vCards, it looks like a bright future for our newly-born URI scheme.

Andy Armstrong of hexten has created yet another implementation of the “geo” URI scheme – this time it’s CPAN module for all the Perl fans out there: URI::geo provides a class to create and parse “geo” URIs from within Perl scripts – a simple example to create a URI from latitude and longitude information looks like this:

use URI::geo;

my $guri = URI::geo->new( { lat => 55, lon => -1 } );

The current module version 0.0.4 is available from CPAN here, API documentation can be found here.

Andy, thanks for implementing and getting the module into CPAN!

As another proof of concept I wrote a little “geo:” URI JavaScript parser.
Basically it scans all anchors in a given text for “geo:” links, extracts location and meta information (e.g. coordinates and corresponding text), places them on a map and appends the map to the text.

I choose to go with a Google Map because I already knew the API, so it was the easiest way. Of course one could modify the script to use any other mapping API’s, create a KML or even transfer the data to a GIS application. If I can free some time in the next weeks I’ll spice the script a little up, some more user defined parameters (e.g. map dimension, marker symbols) and the interpretation of query arguments would be nice though.

See a quick example here: the locations of a few cultural venues are marked with “geo:” anchors, scanned by the script and dynamically shown in the map below.

However, if you’re interested you can download the JavaScript file here. You’ll need a copy of jQuery (I used version 1.1.2) and a valid Google Maps key for your domain too. Then just add the corresponding 3 script elements (Google key, jQuery and geouriparser.js) into the head of your document and let the script find and display the geoURIs in your text.

The idea is heavily inspired by Gutenkarte, a presentation of MetaCarta Labs I remembered from last year’s Where 2.0 conference. Gutenkarte is based on MetaCarta’s Geoparser API, which is of course far more complex than my few lines JavaSrcipt code.

The first version of a firefox extension to handle geo-URIs is now available. The plugin uses a proxy to forward ‘geo:’ requests to a mapping service (currently Google Maps, we’re planning to make this configurable RSN).

(click screenshot to install)

The extension should be compatible with Firefox 1.5 and above – You might need to allow software installations from “p.geouri.org”, and firefox will need to be restarted.

After installation, clicking on the following link should bring up a map of Vienna’s city centre:

geo:48.208333,16.372778

As usual, feedback is appreciated – please note that this extension is currently at a “proof of concept” level, subsequent versions will provide more choice of mapping services via a configuration option. The extension should detect new versions automatically as we release them.