  The key reactions to study the Generalised Parton Distributions are Deeply
Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP).
At COMPASS, these processes are investigated using a high intensity muon beam
with a momentum of 160\,GeV/c and a 2.5\,m-long liquid hydrogen target. In
order to optimize the selection of exclusive reactions at these energies, the
target is surrounded by a new barrel-shaped time-of-flight system to detect the
recoiling particles. COMPASS-II covers the up to now unexplored $x_{B}$ domain
ranging from 0.01 to 0.15. From the sum of cross sections measured with
positive and negative beam polarities, the pure DVCS cross-section and its
$t$-dependence have been extracted resulting in a first model-independent
determination of the transverse size of the partonic distribution of the
nucleon $\sqrt{<r_{\perp}^2>}= (0.578 \ \pm \ 0.042\ _{- \ 0.018}^{+ \
0.006})\,\textsf{fm} $ at a mean $x_{B}$ value of 0.056.
