  Dual parton and quark gluon string model are the by now almost standard
theoretical techniques by which one can arrive at precision description of high
energy, soft, inclusive reactions. These reactions make the part of jets at
energies that contribute strongly to discovery channels such as H$\to$WWjj, or
search for compositeness at the highest transverse momenta. The above modeling
approach is available with Geant4 for nucleon induced reactions since the first
release. Its object oriented design and parameter set was recently extended to
allow for simulation of pion and kaon induced reactions, as well as heavy ion
reactions. We will briefly describe the theory and algorithmic approaches that
underly the modeling, show the object oriented designs and component structure
of the string parton sub-systems of Geant4, present validation/verification
results pertaining to these models, as well as results concerning their usage
in calorimeter simulation.
