This work reviews alternative solutions for retrofitting existing legacy manufacturing information systems with modern bar code tracking hardware and software. Technologies are divided into one-tier architecturs, which include the use of screen scrapers and terminal emulation software; two-tier architectures, which include the use of standard and custom application program interfaces (API); and three-tier architectures, which discuss the application of standards such as CORBA, DCOM, XML messaging, and application protocols for seamless integration with legacy systems. A case study is provided that describes the use of a two-tier API product for implementing a wireless bar code data capture system with a proprietary warehouse management system. Concluding remarks discuss the importance of emerging three-tier architectures and wireless bar code technologies for business-to-business e-commerce applications. The approaches presented here are consonant with the modern view of considering legacy systems as also providing Web services via multiple channels serving multiple categories of clients. © 2004 Society of Manufacturing Engineers.