  We present a new framework for the modelling of hard diffraction in pp and
ppbar collisions. It starts from the the approach pioneered by Ingelman and
Schlein, wherein the single diffractive cross section is factorized into a
Pomeron flux and a Pomeron PDF. To this it adds a dynamically calculated
rapidity gap survival factor, derived from the modelling of multiparton
interactions. This factor is not relevant for diffraction in ep collisions,
giving non-universality between HERA and Tevatron diffractive event rates. The
model has been implemented in Pythia 8 and provides a complete description of
the hadronic state associated with any hard single diffractive process.
Comparisons with ppbar and pp data reveal improvement in the description of
single diffractive events.
