1 ) A method (and computer process) for producing optimal purchase schedules, the method comprising the steps of, a) Creating the supply channels models, said model defining attributes of the supply channel including supply channel master data of items, requisitioning sites, vendors, vendor sites, transport modes; supply agreement parameters; and corporate business rules b) Creating the scope for planning, define optimization configurations, formulating linear programming and mixed integer linear programming models based on the created supply channel models, and run the optimizer c) Analyzing the output purchase schedules, that may consist of real and virtual planning scenarios, through analysis of the purchases costs; basic prices; contractual obligations, rebates and penalties; fulfillment; and schedule compliance to contractual terms d) Further analyzing the enterprise's own compliance on purchase quantities and flex limits; payment terms; and lead time provided for order processing, supply and transportation; costs and taxes; and basic prices; before the purchase schedules are finalized as orders and sent to the vendor