YAZ Proxy can be used in a number of different applications.
Edit by : The YAZ Proxy is highly configurable and can be used in a number of different applications, ranging from debugging Z39.50-based applications and protecting overworked servers, to improving the performance of stateless WWW/Z39.50 gateways. Among other features, it includes:

* Configurable logging
* SRU/SRW server function, to allow any Z39.50 server to also support the Zing protocols
* Load balancing across multiple backend servers
* Session-sharing and pre-initialization to Improve performance in servers with expensive session initialization
* Configurable request filtering, to keep bad requests from reaching the server
* XML support -- MARC records can be converted to MARCXML, and XSLT-transformations allow the proxy to support arbitrary retrieval schemas in XML
* Load governor function limits requests from aggressive Batch-mode clients
* Efficient multiplexing software enables small memory footprint and very high performance you can free download YAZ Proxy 1.3.4 now.