The advanced state of computer networking and telecommunications technology makes it possible to view computers as parts of a global computation platform, sharing their resources in terms of hardware, software and data. The possibility of exploiting the resources on a global scale has given rise to a new paradigm - the mobile computation paradigm - for computation in large scale distributed networks. The key characteristic of this paradigm is to give programmers control over the mobility of code or active computations across the network by providing appropriate language features. The...