It seems Apache::DDI doesn't know what database to connect to. It looks like the DSN is incomplete. Where do you assign a value to $db in db.pl?

The next thing I see is that you're using a single word as your $dsn. By convention a $dsn string takes the form

dbi::driver::dbname;host=$host;port=$port;
[download]

So once you fix the error in the connect_on_init arguments then setPingTimeout might not like the $dsn you're giving it.