  We develop a model to compute high-energy reactions of hadrons and photons.
The perturbative interaction is described by gluon exchange and the
non-perturbative interaction by the stochastic vacuum model which leads to
quark-confinement in dipoles via a string of color fields. We study the QCD
structure of the dipole-dipole scattering in momentum space focussing
especially on interactions between strings. We represent the string as a
collection of stringless dipoles, show confinement effects in high-energy
scattering and calculate unintegrated gluon distributions of hadrons and
photons. In the impact parameter space of the scattering process we investigate
the unitarity limit of the S-matrix. We calculate the impact parameter profiles
for proton-proton and photon-proton scattering, determine the energy values at
which the profiles saturate at the black disc limit, estimate the impact
parameter dependent gluon distribution of the proton and discuss gluon
saturation. We compare the model results for p p, pi p, K p, gamma p and gamma
gamma reactions with experimental data and identify saturation effects in
experimental observables.
