Dirichlet to Neumann operator for abelian Yang-Mills gauge fields

We consider the Dirichlet to Neumann operator for abelian Yang- Mills boundary conditions. We treat the case for space-time manifolds with general smooth boundary components. The aim is constructing a complex structure for the symplectic space of boundary conditions of Euler-Lagrange solutions modulo gauge. Thus we prepare a suitable scenario for geometric quantization of abelian gauge fields following a symplectic reduction procedure in a Lagrangian setting.