  In this paper, we present a detailed analysis of the diagonalization of the
higher spin Heisenberg model using its quantum affine symmetry
$U_q(\hat{sl(2)})$. In particular, we describe the bosonizations of the latter
algebra, its highest weight representations, vertex operators and screening
operators. Finally, we use this bosonization method to compute the
vacuum-to-vacuum expectation values and the form factors of any local operator.
