  We present microscopic QCD calculation of the cross section of diffractive
DIS and of the partonic structure of the pomeron from the dipole approach to
the generalized BFKL pomeron. We show that the pomeron can not be treated as a
particle with uniquely defined structure function and flux in the proton. We
find strong factorization breaking which can approximately be described by the
two-component structure function of the pomeron, each component endowed with
the different flux of pomerons in the proton. We predict very weak $Q^{2}$
dependence of the diffractive contribution to the proton structure function.
