Summary

Since the Internet becomes widely available and popular, metadata models for the Web have evolved over time from simple attribute-value pairs to expressive and powerful languages. The simplicity of the Dublin Core MetaData Set paved the way for Resource Description Framework (RDF) and complementary specifications, and finally the concept of the Semantic Web. In the Semantic Web, metadata and metadata generation is essential to construct document relationships, however, storage and accessibility of the metadata is even more crucial. Vast amount of metadata is generated minute by minute, and new technologies must be investigated and discovered to handle new forms of information flow.

In the following section, we identify common features of metadata repositories and explore related research projects. We have surveyed several projects, and compare them in terms of their features.