Google Maps Enricher

Official documentation

All definitive documentation for the Semarchy xDM Google Maps Enricher is in the Plug-In Reference Guide.

Additional notes

Here are some additional points which may be helpful. These points are subject to change without notice, so be sure to validate them before relying on them.

Useful pointsReference

It's free and works out of the box subject to some limits:

2500 requests per 24 hour period.
50 client-side plus server-side requests per second.

https://developers.google.com/maps/documentation/geocoding/usage-limits

Limits are raised for "Google Maps API Premium Plan" customers:

100 000 requests per 24 hour period (default limit).
50 server-side requests per second (default limit).

https://developers.google.com/maps/documentation/geocoding/usage-limits

Pay-as-you-go billing:

$0.50 USD / 1000 additional requests, up to 100,000 daily.

https://developers.google.com/maps/documentation/geocoding/usage-limits
We use "The Google Geocoding API" v3 for geocoding.
(current as of 2015-06-09) 

Many Semarchy customers use the Google Maps JavaScript API to display a map in a form view.https://developers.google.com/maps/documentation/javascript/

Google is very clear that caching the results is allowed and recommended:
"Whenever possible, pre-geocode known addresses (using the Geocoding API described here or another geocoding service), and store your results in a temporary cache of your own design."

The Semarchy xDM Google Maps Enricher does not have caching built in. But using the Semarchy xDM Lookup Enricher, it's straightforward to implement caching if desired.

https://developers.google.com/maps/documentation/geocoding/geocoding-strategies

Authentication for Google Maps JavaScript API

Customers should add their client ID, provided by Google, when making the API call to display a geocoded Google map. Google also requires registering authorized URLs after adding the client ID, or else the map won't display.

https://developers.google.com/maps/documentation/javascript/get-api-key#client-id

Authentication for Google Maps Geocoding API

The Google Maps Geocoding API is a service that provides geocoding and reverse geocoding of addresses. This is the API used by the Semarchy xDM Google Maps Enricher.

https://developers.google.com/maps/documentation/geocoding/start

Plug-in Outputs

Most outputs returned by the plug-in are the direct results from Google and are documented in the Plug-In Reference Guide.

One exception is the attribute "Quality" which is calculated.

The exact calculation is subject to refinement over time. As of release v4.4, the algorithm is roughly the following:

If Google is able to geocode to a location type of "ROOFTOP" then the quality is 100.
If not, then base the Quality on the size of the bounding box returned by Google. A bounding box of 1 km or larger returns a Quality of 0.
If the bounding box is less than 1 km, then the Quality is a linear calculation: (1000 minus distance in meters) / 10.