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: a due item processing process component that collects, manages, and monitors trade receivables or payables and corresponding sales tax or withholding tax; a project processing process component that structures, plans, and executes simple, short-term measures and complex projects; a balance of foreign payment management process component that collects, processes, and reports receivables and payables according to foreign trade regulations to create a balance of payments of a country; a payment processing process component that processes and manages payments and conducts communications with financial institutions; a customer invoice processing process component that processes invoicing of customers for delivery of goods or provision of services; and an accounting process component that processes business transactions for valuation and profitability analysis; and a plurality of service operations, each service 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: the due item processing process component and a due item processing at business partner process component; the accounting coding block distribution processing process component and the project processing process component; the payment processing process component and the due item processing process component; the customer invoice processing process component and the accounting process component; a bank statement creation at bank process component and the payment processing process component; the due item processing process component and the customer invoice processing process component; the customer invoice processing process component and the balance of foreign payment management process component; the payment processing process component and a payment processing at business partner process component; the payment processing process component and a payment order processing at house bank process component; and the customer invoice processing process component and a supplier invoice processing at customer process component.