1. A computer-accessible memory medium that stores program instructions executable by a processor to: establish a network connection with a server computer over a network; send a universal resource identifier (URI) to the server computer over the network, wherein the URI indicates a graphical program (GP) or a graphical program execution engine (GPEE); and receive the GPEE from the server computer over the network in response to the URI, wherein the GPEE is executable in a web browser of a client computer to execute the graphical program in the web browser; wherein the graphical program comprises a model of a physical system, and wherein the model of the physical system comprises two or more physical domains.