Flower is a new kind of user programmable web service, especially well suited for applications which process, store, and query XML data sets. Clients of a flower web service interactively modify and extend the code the server runs. This is is the ordinary way to build new flower applications. Flower is a true web operating system in the sense that it forms a self-contained, web-addressable computing environment which includes:

• a file-system-like document storage system
• transactional XML database storage with XQuery support
• an interactive shell for invoking programs and editing documents
• an inter-service message passing mechanism
• a uniform naming mechanism for data and processes

The Flower server is a small, server-side program: flower's "kernel". In the current release, the server operates as a Fast CGI handler. It handles requests, manages a server-side database, and contains an interpreter for the Flower Programming Language.

The Flower Programming Language is a simple yet powerful XML notation for describing web processes. Flower web services are written in this language. Simple Flower programming resembles simple unix shell programming: components are often simply "piped" together, each processing as input the output of an earlier program.