  We study the composition operators on an algebra of Dirichlet series, the
analogue of the Wiener algebra of absolutely convergent Taylor series, which we
call the Wiener-Dirichlet algebra. The central issue is to understand the
connection between the properties of the operator and of its symbol, with
special emphasis on the compact, automorphic, or isometric character of this
operator. We are led to the intermediate study of algebras of functions of
several, or countably many, complex variables.
