  The iEBE-VISHNU code package performs event-by-event simulations for
relativistic heavy-ion collisions using a hybrid approach based on
(2+1)-dimensional viscous hydrodynamics coupled to a hadronic cascade model. We
present the detailed model implementation, accompanied by some numerical code
tests for the package. iEBE-VISHNU forms the core of a general theoretical
framework for model-data comparisons through large scale Monte-Carlo
simulations. A numerical interface between the hydrodynamically evolving medium
and thermal photon radiation is also discussed. This interface is more
generally designed for calculations of all kinds of rare probes that are
coupled to the temperature and flow velocity evolution of the bulk medium, such
as jet energy loss and heavy quark diffusion.
