Methods, systems, and apparatus, including computer program products, for implementing a software architecture design for a software application implementing plan-driven procurement. The application is structured as multiple process components interacting with each other through service interfaces, and multiple service operations, each being implemented for a respective process component. The process components include The process components include an RFQ Processing process component, a Purchase Request Processing process component, a Purchase Order Processing process component, a Purchasing Contract Processing process component, a Supplier Invoice Processing process component, a Supply and Demand Matching process component, an External Procurement Trigger and Response process component, and a Customer Requirement Processing process component.