  Adapting the powerful integrability-based formalism invented previously for
the calculation of gluon scattering amplitudes at strong coupling, we develop a
method for computing the holographic three point functions for the large spin
limit of Gubser-Klebanov- Polyakov (GKP) strings. Although many of the ideas
from the gluon scattering problem can be transplanted with minor modifications,
the fact that the information of the external states is now encoded in the
singularities at the vertex insertion points necessitates several new
techniques. Notably, we develop a new generalized Riemann bilinear identity,
which allows one to express the area integral in terms of appropriate contour
integrals in the presence of such singularities. We also give some general
discussions on how semiclassical vertex operators for heavy string states
should be constructed systematically from the solutions of the Hamilton-Jacobi
equation.
