  In this paper, we introduce a weak maximum principle-based approach to
input-to-state stability (ISS) analysis for certain nonlinear partial
differential equations (PDEs) with boundary disturbances. Based on the weak
maximum principle, a classical result on the maximum estimate of solutions to
linear parabolic PDEs has been extended, which enables the ISS analysis for
certain {}{nonlinear} parabolic PDEs with boundary disturbances. To illustrate
the application of this method, we establish ISS estimates for a linear
reaction-diffusion PDE and a generalized Ginzburg-Landau equation with
{}{mixed} boundary disturbances. Compared to some existing methods, the scheme
proposed in this paper involves less intensive computations and can be applied
to the ISS analysis for a {wide} class of nonlinear PDEs with boundary
disturbances.
