1. A computer program product comprising application software encoded on a tangible machine-readable information carrier, the application software being structured as process components interacting with each other through service interfaces, the software comprising: a plurality of process components, each of the process components being a package of software implementing a respective and distinct business process, the plurality of process components including: an Accounting process component that records relevant business transactions; an Internal Request Processing process component that processes internal requests; a Purchase Request Processing process component that provides a request or instruction to the purchasing department to purchase specified goods or services in specified quantities within a specified time; a Purchase Order Processing process component that processes purchase orders and purchase order confirmations; a Goods and Service Acknowledgement process component that processes goods and service acknowledgements, which state a recipient's obligation to pay a supplier for goods received or services rendered; a Supplier Invoice Processing process component that processes supplier invoices, which may be created after a goods and service acknowledgment has been confirmed, and supplier invoice requests, which are sent to invoice verification to advise that an invoice for specified quantities and prices is expected; a Payment Processing process component that handles incoming and outgoing payments as well as represent the main database for a liquidity status; an RFQ Processing process component that handles requests for quotation and corresponding quotes; and a Due Item Processing process component that manages payables and receivables from service and supply; and a plurality of service interface operations, each service interface operation being implemented for a respective process component, the operations comprising inbound and outbound operations, the outbound operation for a first process component being operable to send a message to a second process component of the plurality of process components, the second process component having an inbound operation for receiving the message, the passing of messages between an inbound and an outbound operation defining a message-based pair-wise interaction between the respective process components of the respective operations, the pair-wise interactions between pairs of the process components including interactions between: a Payment Processing process component and an Accounting process component; an Internal Request component and a Supplier Invoice component; a Supplier Invoice Processing process component and Due Item Processing process component; a Purchase Order Processing process component and an Accounting process component; a Purchase Order Processing process component and a Supplier Invoice Processing process component; a Goods and Service Acknowledgement process component and an Accounting process component; a Due Item Processing process component and a Payment Processing process component; an RFQ Processing process component and a Purchase Order Processing process component; a Purchase Request Processing process component and an RFQ Processing process component; a Supplier Invoice Processing process component and an Accounting process component; an Internal Request Processing process component and a Purchase Request Processing process component; an Internal Request Processing process component and a Goods and Service Acknowledgement process component; a Due Item Processing process component and an Accounting process component; and a Goods and Service Acknowledgement process component and a Supplier Invoice Processing process component.