DLXS Programmers & Technical Workshop February, 2002

Middleware Overview

  • Object Oriented Perl CGI programs
  • Set of DLPS-written Perl applications that also use:
    • DLPS-written class, subclass and library modules
    • Perl modules found in the standard distribution
    • Perl modules freely available through CPAN
    • HTML pages and HTML templates
  • Interacts, through DBI, with various DLXS-related databases
  • Basic flow of middleware:
    • Take user input for search
    • Fork off an XPat process
    • Creates as many XPat queries as needed to retrieve results
    • Gather up SGML results
    • Process HTML templates; that is, replace parts of templates with the search results after filtering them to HTML. This creates the final server delivered HTML
  • Through the above modules and databases, the middleware keeps track of collection and user information (either through a session object or a database):
    • search history
    • bookbag / portfolio
    • collection information needed for single collection or cross-collection searching and display behavior