  The main goal of this paper is to put together: a) the Whitham theory
applicable to slowly modulated $N$-phase nonlinear wave solutions to the
focusing nonlinear Schr\"odinger (fNLS) equation, and b) the Riemann-Hilbert
Problem approach to particular solutions of the fNLS in the semiclassical
(small dispersion) limit that develop slowly modulated $N$-phase nonlinear wave
in the process of evolution. Both approaches have their own merits and
limitations. Understanding of the interrelations between them could prove
beneficial for a broad range of problems involving the semiclassical fNLS.
