This study presents a client-server architecture adopted for solution of the Poisson equation, which is a linear equation, used in photomontage. Firstly, a general idea is given about main principle of working of the proposed approach. Secondly, an approach taking into account iterative methods in order to solve the Poisson equation based on Dirichlet boundary conditions is presented. After that it is given a general idea about remote method invocation (RMI) which is used to achieve a client-server architecture in Java programming language and how the RMI approach is put into practice for photomontage. Lastly, tests and generated results are discussed.