Twenty years in CADAL: What we achieved and what comes next

This report reviewed the development of CADAL in the past 20 years, and was divided into three parts. Based on China-US Million Book Digital Library Project, CADAL was developed following the route for digital libraries to evolve into wise libraries, further into knowledge center, and for literature service to transform into knowledge service, raised by academician Mr. Pan Yunhe. Basing on abundant resources, advanced technologies, as well as excellent service, CADAL has signed with almost one thousand libraries home and abroad for resource sharing and joint construction. This report was going to recall the establishment of  Digital Knowledge Service sharing alliance in recent years as a case study, also look forward to the future of CADAL.