We present a case study where a mission-critical legacy hierarchical database, EWIRDB (Electronic Warfare Integrated Reprogramming Database), and its application software are migrated onto a service-oriented web architecture that is based on an XML-based database. EWIRDB stores its data in an extensible tree structure and serves many purposes of supporting EW systems reprogramming, research, development, test, and evaluation; modeling, and simulation, acquisition; and training. We present the historical stages of this migration that helped us to understand the issues and converge to the most appropriate solution eventually. We conclude that recently emerging web service technologies together with native XML database support meet the unique migration requirements of the EWIRDB and its legacy database application. We believe that the proposed solution addresses an almost 20-year old problem in the EW domain problem and forms an appropriate base for porting some other applications with similar requirements in other domains. © Springer-Verlag Berlin Heidelberg 2006.