The systems integration questions really extend beyond database and visualization aspects to include external data processing services such as numerical compute engines, statistical packages, neural networks, and the like. In constructing a system, several different design dimensions must be considered, such as ease of use, performance, size of data, coupling of systems, extensibility, heterogeneity, migration paths, distribution, etc., as outlined previously. In addition, in designing systems such as dataflow or object oriented modeled systems, it may be possible to connect two different procedures, or operations over data, but it may not be meaningful to do so.