Need: An XML Language to describe a sequence of XML actions

Is there an XML vocabulary for describing the sequence of actions upon
XML data?  

Example of a sequence of XML actions: suppose that I want my XML data to
first undergo a transformation using stylesheet #1, and then I want the
output to be validated using schema A, and then ...  

I would like for the desired sequence of actions to be captured in an
XML document.  I would like for there to be a COTS tool that would
orchestrate all of the actions specified in the XML document. 

Does this already exist?  [I see this as being *very* useful for Web
services.]  /Roger