One of the main issues in developing a digital library is how to implement an open digital library which can be interoperable, and diverse concepts, technology and protocols have been introduced to deal with this issue. In this study, it is analysed in terms of 'metadata interoperability', and based on the analysis, 5 basic component technologies are defined as follows: application profiles, modeling, implementation, resource discovery, portal service. Therefore it explains concepts of those core features, characteristics, cases in point, standardization and technical trends.
