At the Information Systems Research Network (FORWIN), Nuremberg, Germany we have prototypically implemented a lean and flexible available-to-promise application which is integrated with a framework of software components fulfilling the functions of supply chain management (SCM). This project is to demonstrate that it is possible to implement cost-effective and flexible software tailored to the needs of small businesses providing reliable information about product availability. To suit a large variety of companies, the way in which the component influences decisions or automates processes can be adjusted through different parameters, such as timeout, substitution, automatic processing or prioritization of suppliers. In order to integrate all sorts of existing MRP or legacy systems along the supply chain the information flow is organized through a transaction-based exchange of standardized XML documents via the Internet.