Principles for coordination and composition of parallel/distributed programs are discussed. We advocate a synchronizing shared memory model (EDA) for coordination and an algebraic approach to building programs using a linking language (LL) based on module composition, restriction and renaming. A prototype system ErlEda illustrating these principles is described. The system uses the concurrent programming language Erlang and its distributed environment as a basis. We illustrate the approach using the Dirichlet problem.