A good candidate for a service to implement as a ruleset is the oBay auction service. You may recall that we looked at the oBay auction process in Chapter 16, Message Interaction Patterns. What we didn't cover in this chapter is the actual implementation of how we calculate the winning bid.
In this scenario, our facts consist of the item up for auction and a list of bids that have been submitted against the item. So we need to implement a set of rules to be applied against these bids in order to determine the winning bid.
The first step in implementing our business rules set is to define our input and output facts. We can create these using the
auction.xsd that we defined as part of ...