47. In a system including a server for servicing requests for resources, and a usage log including information regarding (i) an identification of clients which requested resources referenced, (ii) an identification of resources referenced, and (iii) an identification of times when the resources were referenced, a device for generating a resource transition probability model based on resources referenced by the server, the device including: a) a preprocessor for defining sessions based on the information regarding the identification of clients and the identification of the times; and b) a resource transition probability determining unit for determining resource transition probabilities based on the identification of clients, the identification of resources referenced, and the defined sessions.
52. The device of claim 47 wherein the resource transition probabilities determining unit is a process effected by a machine executing instructions.