This article is an introduction to the "brother and sister" Web Service protocols named Search/Retrieve Web Service (SRW) and Search/Retrieve URL Service (SRU) with an emphasis on the later.
The Z39.50 Target Directory contains all the ANSI/NISO Z39.50 (ISO 23950) and SRU/SRW targets known to us. The tables show the name, address, port, reliability info, search attributes and other data useful for achieving interoperability.
Working through this tutorial you will:
* gain an overview of the history behind the OAI-PMH and an overview of its key features;
* achieve a deeper technical insight into how the protocol works;
* learn something about some of the main implementation issues;
* find some useful starting points and hints that will help you as an implementer.
"SRU (Search/Retrieve via URL) is a standard search protocol for Internet search queries, utilizing CQL (Common Query Language), a standard query syntax for representing queries."
"SRW/U sends a single URL to a remote computer and the remote computer sends back an XML stream. (...) since Web browsers are able to "transform" XML into HTML with a built-in technology called XSLT, the search results are displayed to the user."