Hacking Google Maps and Google Earth (ExtremeTech)

The Google

Maps API

T

he Google Maps API is based on a very simple suite of classes that

you use, within a JavaScript container, directly within an HTML

page. All of the functionality of a Google Map is based on this simple

premise of an embedded JavaScript object built into a web page.

The interface to the API is surprisingly straightforward, but the simplicity

hides some powerful classes, objects, and interfaces that enable you to manip-

ulate the Google Map. By combining this interface with the data that you

want to display, you can support interactive elements on the web page without

having to reload the page or redisplay portions of the map: The entire process

is handled within the JavaScript and Google Maps application.

Using the API Key.

Before you start using the API, you must register with Google and obtain a

Web API key. You cannot use the Google Maps API without a key; Google

will return an error and display nothing if you do not use a key or if you use

the wrong key when you try to use the Google Maps API. For this reason,

the Google Maps API key needs to be referenced in every Google Maps

application you create.

To obtain a Google Maps API key, you must already have an account on

the Google system. If you do not already have an account with Google, you

will need to register with Google first. You will be asked to supply an e-mail

address (which will be used to supply you with your API key).

Once you have you have registered with Google, go to the Google Maps

API web site (http://www.google.com/apis/maps/) and request a

key. The key only works when Google can verify the web site on which your

applications will work. This means that the web site on which you build

your applications must be publicly available on the Internet. Unfortunately,

this also means that you cannot develop applications locally within a net-

work that is not shared directly with the Internet. This includes most

servers in organizations behind firewalls and servers at small businesses and

homes connected to the Internet through a standard xDSL connection such

as ADSL.

̨Learn how to use

the API key

̨Basic components

̨Become familiar

with the API’s main

elements

̨Learn about the

Google Maps

classes

chapter

in this chapter