Mapping Hacks

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Chapter 7, Names and Places

#80 Automatically Geocode U.S. Addresses

HACK

Geocoding with the RDF/REST Interface

REST stands for “Representational State Transfer” and is a way to treat web-

services requests as parameters to standard GET and POST requests. This

means that you enter a normal human-readable URL. To make a RESTful

request to the geocoder, you need to create a URI-safe version of the

address. The address needs to be converted to a form that can appear on the

address line of your browser (which means replacing spaces with

+ signs and

using special escape sequences). Here is an example of a RESTful call. The

advantage over the XML-RPC version is that you can paste this directly into

your browser, so there is no need for XML parsing libraries:

http://rpc.geocoder.us/service/rest?address=1005+Gravenstein+Hwy+N+

sebastopol+ca

This returns an RDF/XML document that includes the results of your

request, which will be displayed in different ways depending on your

browser. Apple’s Safari browser displays the full RDF/XML document, as

shown in Figure 7-3.

Older or non-RDF-aware browsers will ignore the tags that they don’t recog-

nize (such as

<geo:Point>), leaving just the coordinates. Opera reveals the

bare coordinates:

-122.842232 38.411908

Here’s an example of a simple program to script the REST interface with

Perl:

#!/usr/bin/perl

use LWP::Simple;

use URI::Escape;

Figure 7-3. The results of a REST-ful ...