mod_oai: An Apache Module for Metadata Harvesting
  We describe mod_oai, an Apache 2.0 module that implements the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). OAIPMH is the de facto standard for metadata exchange in digital libraries and allows repositories to expose their contents in a structured, application-neutral format with semantics optimized for accurate incremental harvesting. Current implementations of OAI-PMH are either separate applications that access an existing repository, or are built-in to repository software packages. mod_oai is different in that it optimizes harvesting web content by building OAI-PMH capability into the Apache server. We discuss the implications of adding harvesting capability to an Apache server and describe our initial experimental results accessing a departmental web site using both web crawling and OAIPMH harvesting techniques. 
Michael L. Nelson, Herbert Van de Sompel, Xiaoming Liu, Terry L.   Harrison, Nathan McFarland