4.3 How PayPal works

Once defined our business model theoretically we have to pass into it's implementation using the PayPal libraries. In this e-book it will be shown to you the PDT approach which is recommended by PayPal for digital product merchandise.

fig:18 PDT Diagram proposed by PayPal

As you can see at the figure fig:18 there are five steps.

• Customers pays you on PayPal site
This is really easy to be done because PayPal give you the code to add it on your site ('Buy Now' link).
• PayPal sends to you a trandaction ID
This is done by PayPal is not included to our business plan.
• You send transaction Id and your identity token to PayPal.
This is a problem that you, web developer, have to solve. This must be included to our business plan.
• PayPal sends you transactrions details
Ok this is done by PayPal for us. Nothing to do here.
• You display the transactions details of your customer.
This must be included to our business reality.

As you can see the steps 3 and 5 are part of our business reality, so we must code/program them. Not only that but at the step 5 we have to do some controls before giving to our clients the option to download our digital products from our site. This must be a secret controlled link based on the transaction ID with download limitations and lot more security options. So the proposed business plan of Paypal should be modified to something like the figure fig:19

fig:19 PDT Diagram for our business plan

These are really BAD NEWS for the newbies, don't you think? You have to have programming skills in order to make this realization. Do not worry, this e-book will do all the coding for you. You only have to set some settings in order to get a fully functional solution. As far as you can see you only have to set attributes and no coding is needed to get your site up and running. The complete solution of the interfacing of your site with PayPal is given by the figure fig:20.

fig:20 Solution proposed and applied by this e-book

As you can see the step 3 is done by pdthtml.php and the step 5 is done by the DownloadManager.php. All these diagrams are only trying to give you an idea of the internal structure of our site. Even if you do not understand them, the solution proposed in this e-book will work for you. We just want to give to the reader a general view of the architecture of the final web site.