Google Hacks

5.2 Why an API?

When search engines first appeared on the scene, they were more open to being spidered, scraped, and aggregated. Sites like Excite and AltaVista didn't worry too much about the odd surfer using Perl to grab a slice of page, or meta-search engines including their results in their aggregated search results. Sure, egregious data suckers might get shut out, but the search engines weren't worried about sharing their information on a smaller scale.

Google never took that stance. Instead, they have regularly prohibited meta-search engines from using their content without a license, and they try their best to block unidentified web agents like Perl's LWP::Simple module or even wget on the command line. Google has further been known to block IP-address ranges for running automated queries.

Google had every right to do this; after all, it is their search technology, database, and computer power. Unfortunately, however, these policies meant that casual researchers and Google nuts, like you and I, don't have the ability to play their rich data set in any automated way.

In the Spring of 2002, Google changed all that with the release of the Google Web API (http://api.google.com/). The Google Web API doesn't allow you to do every kind of search possible, for example, it doesn't support the phonebook: [Hack #17] syntax, but it does make the lion's share of Google's rich and massive database available for developers to create their own interfaces and use Google search results to their liking.

API stands for "Application Programming Interface," a doorway for programmatic access to a particular resource or application, in this case, the Google index.

So how can you participate in all this Google API goodness?

You'll have to register for a developer's key, a login of sorts to the Google API. Each key affords its owner 1,000 Google Web API queries per day, after which you're out of luck until tomorrow. In fact, even if you don't plan on writing any applications, it's still useful to have a key at your disposal. There are various third-party applications built on the Google API that you may wish to visit and try out; some of these ask that you use your own key and alotted 1,000 queries.