Hacking Google Maps and Google Earth (ExtremeTech)

60 Part I — Basics

Each individual query counts as 1 toward your 1,000-per-day limit. The limit is by query, not by

unique query string. In this case, you had to perform nine queries to get all of the results for just

one query string.

Comparing Language Samples

Google Maps examples consist of JavaScript and the HTML that makes up the page. But the

backend information that you might store or compose will probably be sourced through an

alternative language.

The Google Web API uses the Simple Object Access Protocol (SOAP), which means that it is

accessible from just about any language. This section concentrates on Perl and Java for backend

solutions, because they are two of the more common languages in use.

Perl

With Perl, you first need to download and install the SOAP::Litepackage and all the other

modules on which the SOAP::Litemodule relies (including the XML::Parserand others).

If you are familiar with CPAN, this should be a simple task. Just use the following command

(under Unix/Linux):perl -MCPAN -e ‘CPAN::Shell->install(“SOAP::Lite”)’.

Without CPAN, you’ll need to manually download the main SOAP::Litepackage and the

modules on which it relies. When using the ActivePerl distribution in Windows, use the Perl

Package Manager (PPM) or Visual Package Manager (VPM).

Once you install the SOAP::Litemodule, submitting the query to the Google search service

is relatively simple. Listing 4-1 shows a simple search (without any processing or printing of

the results).

Beyond Searches

The primary reason for using the Google Web API is to get a list of web sites that match a par-

ticular query and, thus, might be useful to you when building your Google Maps. You can, how-

ever, access two other Google systems through the Google Web API: the spelling system and

the cache system.

The spelling system provides alternate spellings for words or phrases that you supply. The same

system uses the information in the Google database to suggest sensible alternatives when you

submit a search (for example, if you searched for “Bratney Spires,” it would suggest an alter-

nate — and correct — spelling: “Britney Spears”).

The cache system returns the cached document content for a given URL. The text returned is

the raw HTML for the URL, assuming that it exists in the Google database, as it was stored from

the last Google web crawl.

Both these systems are described further in the Google Web API documentation but are not

generally useful for Google Maps applications.