SRU (Search and Retrieve via URL) is a standard search protocol developed by the Library of Congress to allow web-based access to libraries. SRU uses a fairly simple query language called CQL (Contextual Query Language). Any program that can send a HTTP GET request to a remote site and receive the resulting XML document is basically suited as a SRU client. This is especially true for your web browser and for command-line utilities like wget, but a dedicated client like YAZ may be more convenient for all but the most simple queries. Also, some software packages read bibliographic data from databases via SRU (e.g. citeproc).

RefDB implements SRU server capabilities through a CGI script that you can optionally install in your web server. This will allow anyone with access to your web server to search and retrieve bibliographic data in your RefDB databases. Alternatively, a standalone web server for single-user access is available too. This chapter explains how to use SRU access. See the installation chapter for the instructions how to set up SRU support in your RefDB installation.