Policy Model

As was said in Chapter 1, the redirection policy defines the method of replica selection. It takes as input the address of a client and the list of replica addresses (which are assumed to belong to the same service). Having this information the policy chooses a specific number of addresses of replicas that are likely to service the client most efficiently. Although this task may seem simple (if not primitive), the optimal set of addresses can be very hard to identify. As we will see later in this chapter, the selection algorithm can be very sophisticated.