The swish extension provides the bindings for Swish-e API. Swish-e stands for "Simple Web Indexing System for Humans - Enhanced" and is an open source system for indexing and search. Swish-e itself is licensed under GPL license, but uses a clause that allows applications to link against the library if every copy of the combined work is accompanied by the URL to Swish-e source code. Here it is: ยป http://swish-e.org.
This extension is EXPERIMENTAL. The behaviour of this extension including the names of its functions and any other documentation surrounding this extension may change without notice in a future release of PHP. This extension should be used at your own risk.