This chapter illustrates the impact on a well{known digital library system { Greenstone { when it is moved from fixed modules and simple metadatabased structures, to open semantic digital library modules. This change has profound effects on the tools available to end-users to retrieve relevant content from the library, and an equally significant impact on the digital library (DL) architecture. Most current DL systems contain protocols for internal communication that define information exchange solely in terms of searching, browsing, and document retrieval. These communications reect traditional user interactions in the library. However, this regimented approach results in inexible systems that are difficult to extend to support other retrieval techniques. Furthermore, simple field-based metadata limits the ability of the DL to connect or disambiguate key items of information, impeding the precision of retrieval.