- - loads external filter modules used for presenting
- the recods in a search response.
- - executes search requests in PQF/RPN, which are handed over from
- the YAZ server frontend API
- - calls resorting/reranking algorithms on the hit sets
- - returns - possibly ranked - result sets, hit
- numbers, and the like internal data to the YAZ server backend API.
- </para>
+ The core Zebra module is the meat of the <command>zebraidx</command>
+ indexing maintenance utility, and the <command>zebrasrv</command>
+ information query and retrieval server binaries. Shortly, the core
+ libraries are responsible for
+ <variablelist>
+ <varlistentry>
+ <term>Dynamic Loading</term>
+ <listitem>
+ <para>of external filter modules, in case the application is
+ not compiled statically. These filter modules define indexing,
+ search and retrieval capabilities of the various input formats.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Index Maintenance</term>
+ <listitem>
+ <para> Zebra maintains Term Dictionaries and ISAM index
+ entries in inverted index structures kept on disk. These are
+ optimized for fast inset, update and delete, as well as good
+ search performance.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Search Evaluation</term>
+ <listitem>
+ <para>by execution of search requests expressed in PQF/RPN
+ data structures, which are handed over from
+ the YAZ server frontend API. Search evaluation includes
+ construction of hit lists according to boolean combinations
+ of simpler searches. Fast performance is achieved by careful
+ use of index structures, and by evaluation specific index hit
+ lists in correct order.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Ranking and Sorting</term>
+ <listitem>
+ <para>
+ components call resorting/re-ranking algorithms on the hit
+ sets. These might also be pre-sorted not only using the
+ assigned document ID's, but also using assigned static rank
+ information.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Record Presentation</term>
+ <listitem>
+ <para>returns - possibly ranked - result sets, hit
+ numbers, and the like internal data to the YAZ server backend API
+ for shipping to the client. Each individual filter module
+ implements it's own specific presentation formats.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>