Supporting broad internet access to TACOMA

The TACOMA system [JRS95] provides operating-system support for mobile processes, or agents, that traverse the hosts of a network in accomplishing some task. A TACOMA agent executing on one host moves to another host by using TCP to communicate with TACOMA software at the destination host. The presumption is that TACOMA software has been installed at any host that might launch or be visited by an agent. This presumption is questionable:• System managers are reluctant to install software that allows arbitrary imported software, like agents, to be executed on their hosts. And, there is good reason for this reluctance.• Hosts are autonomous. So, even were security not a concern, arranging for installation of a piece of non-critical software on a significant fraction of the hosts in a large network is impractical.The network-software installation-problem is not unique to agents or to TACOMA. Any provider of software will be faced with this problem if that software must be installed on autonomous sites of a large network. The speed with which WWW software spread through the Internet was an exception; architects of distributed-application support-software should not plan on having their systems disseminated in such a fashion. But, these architects better have some plan for disseminating their systems, since the utility and success of large networks will depend on offering new services in a timely way.This paper reports experiences in addressing the network-software installation-problem for TACOMA. However, we believe that the techniques employed have utility in other situations as well. The next section gives an overview of TACOMA and the applications it currently supports. Section 3 describes a WWW-based scheme for avoiding software installation at all sites that might launch TACOMA agents; section 4 discusses an email-based scheme. Section 5 concludes with a summary and some observations.