Hacking Google Maps and Google Earth (ExtremeTech)

266 Part III — Google Map Hacks

Database Structure.

The application stores routes, and for each route there are two distinct sets of information. The

first is the basic information about the route (the name and description). A route ID will be

added so that you have a unique identifier for the route.

That route table (called ch13_routesimplefor the purposes of this example) will be linked

by the unique route ID to another table that contains the list of points. The table consists of

the route ID, the latitude and longitude of each point, and a unique sequence ID.

Basic Wrapper

The core of the CGI backend is the wrapper. The wrapper includes the interface to the

database. It also controls how communication between the JavaScript components and the

backend work to exchange information, such as route submissions, requests for lists of routes,

and individual route information.

For that there is a simple wrapper, as in previous examples, that initiates the connection to the

database and then extracts requests through the CGI interface and makes calls to the right

function to perform the desired option. The code for this follows:

#!/usr/bin/perl

use DBI;

use Math::Trig;

use strict;

use CGI qw/:standard/;

print header(-type => ‘text/xml’);

my $dbh = DBI->connect( ‘dbi:mysql:database=mapsbookex;host=db.maps.mcslp.com’,

‘mapsbookex’,

‘examples’,

);

if (!defined($dbh))

{

die “Couldn’t open connection to database\n”;

}

if (param(‘m’) eq ‘saveroute’)

{

saveroute();

}

if (param(‘m’) eq ‘delroute’)

{

delroute(param(‘routeid’));

}

elsif(param(‘m’) eq ‘listroutes’)

{

listroutes();

}