Contemporary analogous systems for SDI services include alerts, current awareness tools or trackers.
Software was developed in many companies and in government to provide this service in the 1950s and 60s, which allowed distribution of items recently published in abstract journals to be routed to individuals who are likely to be interested in the contents.
For example, the system at Ft. Monmouth automatically sent out (by mail) a different set of abstracts to each of about 1,000 scientists and engineers in the army depending on what they were working on.
Librarians or information professionals conducted extensive interviews with their clients to establish a fairly complex profile for each individual.
The software was developed by Edward Housman at the Signal Corps Laboratories Technical Information Division.