  A new method to compute the symplectic structure of a quantum field theory
with non trivial boundary conditions is proposed. Following the suggestion in
\cite{ho:gnus, ardalan}, we regard that the boundary conditions are second
class constraints in the sense of the Dirac's method. However, we show that
this proposal is more useful if we consider an inverse of the Holographic map
between a theory defined in the boundary to another with constraints but
without boundary.
