1. A method of allocating data processing across a first data processing system and a second data processing system, where the amount of processing allocated to each data processing system is dynamically adjusted depending on remaining resources available to the second data processing system based on a service level that at a user of the second data processing system has subscribed to, the method comprising: the first data processing system receiving information defining how a result associated with a data processing task will be rendered at the second data processing system; the first data processing system accessing information indicating a service level that at a user of the second data processing system has subscribed to, and that defines an allocation of processor resources of the first data processing system granted for use on behalf of the second data processing system; the first data processing system determining, based on the service level, an amount of processor resources of the first data processing system that remain from the allocation of processor resources of the first data processing system granted for use on behalf of the second data processing system; the first data processing system determining needed data processing to be performed for providing the result at the second data processing system; and the first data processing system dynamically allocating the needed data processing between the first data processing system and the second data processing system, based on the service level, wherein the needed data processing includes a first portion allocated to the first data system and a second portion allocated to the second data processing system, the first portion being larger compared to the second portion when the needed data processing requires less than the amount of processor resources that remain from the allocation of processor resources, and the first portion being smaller compared to the second portion when the needed data processing requires more than the amount of processor resources that remain from the allocation of processor resources.