Geocoding - finding the geographical location of a given address - is one of the most popular features of the Google Maps API. Both the JavaScript Maps APIs and the Maps API for Flash include classes that enable applications to perform geocoding, and there is also a RESTful web service that offers the option of making geocoding requests from server side applications with output in both XML and JSON.
The Google Maps JavaScript API v3 introduced a new format for geocoding responses that offers a number of improvements over the format used in the v2 API:
The Geocoding Web Service is intended to enable precaching of geocoder results that you know your application will need in the future. For example, if your application displays property listings, you can geocode the address of each property, cache the results on your server, and serve these locations to your API application. This ensures that your application does not need to geocode the address of a property every time it is viewed by a user. However we do ask that you regularly refresh your cache of geocoder results.
Note however that it is a requirement of the Maps API Terms of Service that you use the Geocoding Web Service in conjunction with a Google map. This means that when it comes time to use cached geocoder results in an application, the application must display the results or any data derived from them on a map generated using one of the Google Maps APIs or Google Earth API.
If your application needs to geocode arbitrary addresses that are entered by your users while they wait we recommend that you use the classes in the appropriate client API. This ensures that the requests your application generates reach Google directly from your users, which will improve the performance of your application and ensure it is resilient to unexpected spikes in use. For more details, I highly recommend this excellent blog post by our very own Mano Marks.
In addition to an improved response format you will notice some other changes in the new Geocoding Web Service. Requests no longer require a Maps API key, and Maps API Premier customers must sign their requests. In addition CSV output is not supported because we found that the minimal amount of data in a CSV response makes it is difficult to identify false positive results.
2,500 requests may be sent to the Geocoding Web Service per day from a single IP address. This is independent of any geocoding activity generated by applications using one of the client Maps APIs for geocoding. Maps API Premier quotas remain unchanged.
A forward geocoding request to the new Geocoding Web Service with XML output looks like:
http://maps.google.com/maps/api/geocode/xml?address=sydney&sensor=false
A reverse geocoding request with JSON output looks like:
http://maps.google.com/maps/api/geocode/json?latlng=-33.873038,151.20563&sensor=false
Check out the Geocoding Web Service documentation for more details on the options available for language and biasing of results.
In conjunction with the launch of the new Geocoding Web Service we are also announcing the deprecation of the current service, now retroactively named the "Geocoding V2 Web Service". Existing applications using the V2 Web Service need not worry though. Deprecation indicates that we no longer intend to pursue any further feature development, but we will continue to maintain and support the service in accordance with the deprecation policy set out in the Maps API Terms of Service.
We hope that you find the new Geocoding Web Service easier to use and useful. As always we encourage you to check out the Google Maps API Google Group if you have any questions or comments relating to the APIs. We look forward to adding more great features to the Geocoding Web Service in future.
Posted by Thor Mitchell, Maps API Product Manager
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