One clickthrough per IP per day

The first idea I implemented was to only count one clickthough per IP address per day. I didn't want to use a database or file to store the IP addresses, and then search for them - that's a little over the top. So I had the idea that I'd use an Application variable - which would get emptied each day.

The BrandNewDay ( ) function

First I initialized some variables. This code was added to global.asa's Application_OnStart function - IIS calls this function automatically when the server starts up...

function Application_OnStart ( ) {    Application.Lock ( );    // remember todays date    var d = new Date;    Application ( 'Today' ) = d.getDate ( );    // initialize new stuff in utils/Init.asp    Application ( 'BrandNewDay' ) = 1;    // a list of IP addresses that have clicked an ad    Application ( 'ClickFromIP' ) = '';    Application.Unlock ( ); }

...then I reset the BrandNewDay when the date rolled over (incidentally, I can also reset it manually by calling the BrandNewDay.asp page, which is sometimes handy. I'll leave you to look at that page):

function Session_OnStart ( ) {    Application.Lock ( );    // is it a new day?    var d = new Date;    if ( Application ( 'Today' ) != d.getDate ( ) )       Application ( 'BrandNewDay' ) = 1;    Application.Unlock ( ); }

Now I know when the day changed I modified utils/Init.asp so that a new BrandNewDay ( ) function gets called when this Application variable is set. I also cleared the Application ( 'ClickFromIP' ) variable that I'll use in a minute:

// ============================================ // anything that needs doing once per day! // ============================================ function BrandNewDay ( ) {    if ( Application ( 'BrandNewDay' ) == 1 )    {       Application.Lock ( );       // clear the list if IP addresses that are ignored       Application ( 'ClickFromIP' ) = '';       Application ( 'BrandNewDay' ) = 0;       Application.Unlock ( );    } }

Part 3: Application ( 'ClickFromIP' )...