Most existing commercial packages, such as Product Data Management (PDM), Enterprise Resource Planning (ERP), and Commerce at the Light Speed (CALS), are likely to have some problems; the cost of each package can be rather high and sometimes it can be hard to apply general packages to the specific tasks of companies. This paper presents a resource planning system (RPS) for small- and medium-sized companies that produce compound semiconductor wafers. The RPS adopts a concurrent paradigm to provide customers with credible delivery information in the ordering stage, as well as addresses lots of issues arising from a shop floor. The system is composed of five modules including Order Management, Production Scheduling, Work-in-process Management, Warehouse Management, and Product Inventory Management. These modules are implemented by web applications using Active Server Pages coded in Visual Basic Script. They are managed by an SQL database server on a Windows NT environment.