Metadata is data about data. It is considered an ideal and a very useful solution in describing/managing resources on the Internet. Especially, in the digital library field, metadata plays an important role for integrating digital resources and offering information service. However, from users standpoint, information service offered nowadays by any digital library is unable to satisfy their diversified needs, such as, knowledge information, individualization information, reusable and sharable information. A metadata model based on a new concept is required. As an extension of our previous research issue, we proposed the concept of Structured Digital Object (SDO is an abbreviation). SDOs are used for reorganizing/restructuring existing digital resources, because SDO set is structured data about data, this paper call it metadata. Using the metadata model based-concept of SDO, restructure various existing resources in existing digital libraries, form the so-called "Global Digital Library". The Global Digital Library can adopt Web Services for information services. It can solve not only interoperability problems among heterogeneous resources, heterogeneous systems and operating systems, but also can meet individual user need to different granularities information. We also used Topic Maps to associate SDOs with information resources that can be located in existing digital libraries or the global digital library. Furthermore, because all the metadata is described by XML, achieve reusing, sharing information. In the paper, we give some demonstrations to approve the points described above.