At the present time the electronic library supports a number of data management and access tools (discussed below) to provide access to the database. Some of these tools, such as Gopher and simple FTP rely on the hierarchic structuring of the page image and text files to provide access. The World-Wide-Web server provides access to the technical report via indexes maintained by a set of perl scripts and ``c'' programs.
However, the primary electronic library server under development at Berkeley is a POSTGRES-based system that can communicate using the Z39.50 protocol. POSTGRES is a next-generation DBMS that supports user-defined abstract data types, user-defined functions, a rules system, and many of the features of Object-Oriented DBMS (including inheritance and methods via functions in both the query language and conventional programming languages). Details on the use of POSTGRES for indexing and retrieval in the CSTR electronic library are provided in the next section.
Further extensions to the POSTGRES system are underway. Of particular importance is the development of a Z39.50 compliant interface to the POSTGRES system. Our server will function by mapping requests in the standard Z39.50 protocol into queries the POSTGRES query language. We are also in the planning stage of development to include additional database support for a new class of DBMS access methods that will provide both effective and efficient indexing and retrieval in support of advanced IR methods.