1. A data warehousing method, comprising: storing a plurality of transformation templates in a transformation library, each transformation template including metadata objects that describe how to transform extracted data prior to loading the data into a data warehouse; associating a unique identifier with each of the plurality of transformation templates; instantiating an instance of at least one of the plurality of transformation templates into a data transformation process via the unique identifier associated with the at least one transformation template, wherein the metadata objects of the transformation template are mapped into the instance of the transform using executable code segments; and executing the data transformation process to transform and load the extracted data into the data warehouse.