8. A non-transitory computer-readable storage medium comprising: a medium configured to store computer-readable instructions thereon; and the computer-readable instructions that, when executed by is processing device cause the processing device to perform a method, comprising: sending a recursive rules engine to a client device, wherein the rules engine comprises a set of discount rules configured for automatically de fining a purchase order discount from a coupon code when a purchase order is made and when a purchase order is modified, and wherein execution of the rules engine comprises: recursively evaluating the first set of rules for determining an applicability of the purchase order discount; recursively evaluating a second set of rules for determining a discount value relating to an applicable discount; recursively evaluating the first set of rules and the second set of rules by performing an automatic process that recursively calls itself; receiving a purchase order placed by a user of the client device along with a coupon code; receiving the purchase order discount from the client device for the purchase order as automatically determined by the rules engine upon placement of a purchase order; relying on the determination of the rules engine; applying the discount without independently determining the purchase order discount; and processing the purchase order along with purchase order discount.
8. A non-transitory computer-readable storage medium comprising: a medium configured to store computer-readable instructions thereon; and the computer-readable instructions that, when executed by is processing device cause the processing device to perform a method, comprising: sending a recursive rules engine to a client device, wherein the rules engine comprises a set of discount rules configured for automatically de fining a purchase order discount from a coupon code when a purchase order is made and when a purchase order is modified, and wherein execution of the rules engine comprises: recursively evaluating the first set of rules for determining an applicability of the purchase order discount; recursively evaluating a second set of rules for determining a discount value relating to an applicable discount; recursively evaluating the first set of rules and the second set of rules by performing an automatic process that recursively calls itself; receiving a purchase order placed by a user of the client device along with a coupon code; receiving the purchase order discount from the client device for the purchase order as automatically determined by the rules engine upon placement of a purchase order; relying on the determination of the rules engine; applying the discount without independently determining the purchase order discount; and processing the purchase order along with purchase order discount. 9. The not computer-readable storage medium of claim 8 , wherein the purchase order discount comprises a discount type and a discoing value relating to the discount type for the purchase order.