  The dc Josephson effect is considered from the thermodynamic point of view.
Universal thermodynamic equations, relating both bound and continuum
contributions to the Josephson current with the normal electron scattering
amplitudes are derived for the single mode case. To derive these equations we
use and further develop the method of spatial separation between the
superconducting and normal parts of the junction. We also use this method to
find the Andreev bound states in structures containing superconducting
components. The general thermodynamic formulas are applied to the calculation
of the current in various Josephson-type structures. In particular, the crucial
role of the continuum contribution is demonstrated, even for short junctions
(where it is usually neglected). We also find structures where the bound states
supporting the giant currents are well separated; thus they can, hopefully, be
populated nonuniformly and such current can be measured.
