Sun's Java popularized the technique of mobile programs, that is, which travel on an internetwork. Network communications have enable to extend the subroutine call mechanism up to use, in addition to local, remote ancillary processing power through an internetwork. Now they enable local execution of programs upon their downloading from some place on the network web. We examine several aspects of this evolution from the point of view of practical design of distributed applications, from which we extract some basic characteristics. With these characteristics in mind, we examine a two main alternative propositions for designing mobile applications. The conclusion of this study points out six landmarks in the whirling landscape of networked software technology.