  Initial applications of the GriPhyN Chimera Virtual Data System have been
performed within the context of CMS Production of Monte Carlo Simulated Data.
The GriPhyN Chimera system consists of four primary components: 1) a Virtual
Data Language, which is used to describe virtual data products, 2) a Virtual
Data Catalog, which is used to store virtual data entries, 3) an Abstract
Planner, which resolves all dependencies of a particular virtual data product
and forms a location and existence independent plan, 4) a Concrete Planner,
which maps an abstract, logical plan onto concrete, physical grid resources
accounting for staging in/out files and publishing results to a replica
location service. A CMS Workflow Planner, MCRunJob, is used to generate virtual
data products using the Virtual Data Language. Subsequently, a prototype
workflow manager, known as WorkRunner, is used to schedule the instantiation of
virtual data products across a grid.
