Wonka Rules Engine : Intermediate Example : Prevalidation of Purchase (Biz Rules)

<?xml version="1.0"?>
<RuleTree xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

   <if description="Start a new sales transaction">
      <criteria op="AND">
         <eval id="pop1">(N.NewSalesTransSeq) POPULATED</eval>
      </criteria>

      <if description="Checking Input Values">
           <criteria op="AND">
               <eval id="pop2">(N.ProductEAN) POPULATED</eval>
               <eval id="pop3">(N.ProductSalesRightsList) POPULATED</eval>
               <eval id="pop4">(N.Buyer) POPULATED</eval>
               <eval id="pop5">(N.BuyerResidentCountry) POPULATED</eval>
           </criteria>

           <validate err="severe">
               <criteria op="OR">
                   <eval id="eq1">(N.ProductSalesRightsList) == ('WORLD')</eval>
                   <eval id="in1">(N.BuyerResidentCountry) IN (N.ProductSalesRightsList)</eval>
               </criteria>

               <failure_message>ERROR!  Sales rights for item do not exist in buyer's country of residence.</failure_message>
               <success_message/>
           </validate>           
       </if>

   </if>    
    
</RuleTree>