Eventually, we would like to develop a full system of remote software maintenance. Conventional maintenance (a support group which mails tapes) has many well-known disadvantages. brooks mythical man month 1975 There are distribution errors and delays, resulting in old software running at remote sites and old bugs continually reappearing. These difficulties are aggravated when there are 100 different small systems, instead of a few large ones.
The availability of file transfer on a network of compatible operating systems makes it possible just to send programs directly to the end user who wants them. This avoids the bottleneck of negotiation and packaging in the central support group. The ``stockroom'' serves this function for new utilities and fixes to old utilities. However, it is still likely that distributions will not be sent and installed as often as needed. Users are justifiably suspicious of the ``latest version'' that has just arrived; all too often it features the ``latest bug.'' What is needed is to address both problems simultaneously:
To do this, we recommend systematic regression testing both on the distributing and receiving systems. Acceptance testing on the receiving systems can be automated and permits the local system to ensure that its essential work can continue despite the constant installation of changes sent from elsewhere. The work of writing the test sequences should be recovered in lower counseling and distribution costs.
Some slow-speed network services are also being implemented. We now have inter-system ``mail'' and ``diff,'' plus the many implied commands represented by ``uux.'' However, we still need inter-system ``write'' (real-time inter-user communication) and ``who'' (list of people logged in on different systems). A slow-speed network of this sort may be very useful for speeding up counseling and education, even if not fast enough for the distributed data base applications that attract many users to networks. Effective use of remote execution over slow-speed lines, however, must await the general installation of multiplexable channels so that long file transfers do not lock out short inquiries.