YAZ is a programmers’ toolkit supporting the development of Z39.50/SRW/SRU clients and servers. Z39.50-2003 (version 3) as well as SRW/SRU version 1.1 are supported in both the client and server roles.
Zebra is a high-performance, general-purpose structured text indexing and retrieval engine. It reads structured records in a variety of input formats (eg. email, XML, MARC) and allows access to them through exact boolean search expressions and relevance-ranked free-text queries.
... [More] large databases (more than ten gigabytes of data, tens of millions of records). It supports incremental, safe database updates on live systems. You can access data stored in Zebra using a variety of Index Data tools (eg. YAZ and PHP/YAZ) as well as commercial and freeware Z39.50 clients and toolkits. [Less]