The XTF Text Engine is responsible for parsing and executing queries against
the Lucene index. The actual work of building an index is done by the textIndexer
tool.
Here's a breakdown of the Texdt Engine's major functions, and the classes associated
with each function:
Query Parsing
Takes care of calling the queryParser stylesheet to transform a URL query request
into a strictly structured, XML-formatted query. Also accumulates a list of terms
present in the query (useful later for term highlighting.)
Query Processing
These classes implement the main logic of the package, taking a structured query
and applying it to the Lucene indexes. They handle stop-word (n-gram) query pre-processing,
and scoring and sorting the hits
Limiting Work Performed by a Query
To help ease server load problems due to unwitting or malicious queries, XTF has
added an extensive layer of work limiting on top of Lucene.
Retrieving Query Results
Once a query has been performed, the following classes provide access to the document
hits, and to text snippets within each document.
Utility classes
These classes don't fit into any other category.