To perform a transaction with FPS, all the participants in the transaction must approve a set of payment instructions that will be installed in their Amazon Payments account. FPS does not allow one account holder to install tokens in an account that belongs to another entity, so all the parties involved in a transaction must install their own tokens.
If a participant in a transaction has an FPS developer account and an API client implementation, they can install tokens themselves using the techniques discussed in Install Payment Instructions (Create a Token).” In most situations, your FPS applications will be transferring money to or from third parties who do not have the expertise or inclination to interact with FPS through the API interface. The CBUI pipeline provides an easy-to-use web site for third parties to view a set of payment instructions, approve these instructions, and create a token to authorize the transaction. When your application needs to acquire a token from a third party, such as a customer, it can direct him to the CBUI pipeline with a specially crafted URI that specifies the payment instructions you are proposing.
Figure 10-1 demonstrates a sequence of events that would occur in one of the most common FPS application scenarios: a customer making a purchase from an online store application built using FPS:
The store application displays items on a web page with a “Buy” link nearby. Each URI link is specially crafted for the CBUI pipeline ...