respond to different format

Hi,

I am now developing an application that require a function that output the format corrspending to the request required, such as if browser request html, it respond the data in html format, and output the csv formated file when client is requesting the csv presentation of data.

I am currently using the respond_to block to enclose this dispatching of the different output requested from client. On Rails, it support to specify the html as parse from rhtml, but how to let rails to specify csv for output? and how to make a template for outputting csv like rhtml output html ?

Thank, Patrick