1. A multi-tier inventory management data processing system comprising: an inventory management system executing in memory of a computing system and coupled to one or more e-commerce applications over an enterprise bus; and, a plurality of instances of a single tier inventory component, each of the instances corresponding to a different local inventory cache from amongst a plurality of local inventory caches, each instance of the tier inventory component comprising program code enabled upon execution in memory of a computer to prime a corresponding one of the local inventory caches with a subset of inventory data for the inventory management system, to manage a correspondingly different local inventory cache, each instance further comprising an inventory management application programming interface (API) exposing for access by other instances of the tier inventory component, a selection of inventory operations on the correspondingly different local inventory cache, the operations being defined within the program code of the instance of the tier inventory component.