The software will be distributed as open source. Increasingly web editions are the version of record and paper versions of the same titles are merely a subset of peer reviewed scholarly discourse. Librarians need an inexpensive, robust mechanism, that they control, to ensure their communities maintain long-term access to this important literature. There is no single solution to this problem. Any single solution would be perceived as vulnerable.
Diversity is essential to successful preservation.
Thus pages will be preserved even if they aren't read. Through these caches each library takes physical custody of selected Web journals it purchases. Over time, the disks holding an individual cache will fill up or fail. If a cache detects that its content is incomplete or otherwise corrupt it asks the publisher or one of the other caches to provide a replacement copy. What extra replicas can buy is interesting computer science research.