Composable and Reusable Business Rules Using AspectJ*

public class BRPriceDiscount{ private Float percentage; abstract public boolean condition(); public Float action(Float price){...} public Float apply(Float price){ if (condition()){ return action(price); else{return price}; } } } Suppose we consider two concrete price personalization business rules: BR1 if today is Christmas then a customer gets a 5% discount and BR2 if the customer has bought more than 10 products then he or she gets a 10% discount on the current purchase. The implementation in JavaTM of these rules, BRChristmasDiscount and BRPurchasedItemsDiscount respectively is shown below. They define concrete implementations for the inherited method condition(). public class BRChristmasDiscount extends BRPriceDiscount{ private boolean isChristmas(){...} public boolean condition(){ return isChristmas(); } } public class BRPurchasedItemsDiscount extends BRPriceDiscount{ Customer customer; public void setCustomer(Customer c){ customer = c; } public boolean condition(){ // returns if customer purchased more than 10 products } } As part of the connectivity layer we need to define the following aspects: An aspect EPricePersonalisation identifies the event in the core application that defines the application time of both business rules