Trickle

TRICKLE was a file-forwarding service on the BITNET (EARN/NetNorth/GulfNet) network.

When it was created, many sites in Europe only had access to BITNET or compatible networks, and not to the Internet. Therefore, there was a great need to access files that were available only on the Internet. The TRICKLE server allowed anyone on the BITNET-compatible networks to access hundreds of thousands of files from many popular FTP servers around the world.

The TRICKLE server was a 'concentrator' of FTP sites into central servers. Each server had its own (large) cache disk to store files that have been recently ordered by users, and was in communication with all other TRICKLE servers about the contents of its cache. When a user ordered a file that is not in local cache, TRICKLE could usually forward this command to one other TRICKLE server that was known to hold the file. In some cases, "broadcasts" to all other TRICKLEs for this file is necessary, and if the file is new, or accessed very infrequently, it was requested from one of the 3 FTP slave-servers it had. These 3 were special servers who fetch the file via FTP and send it via NJE to TRICKLE.

TRICKLE servers reduced load on FTP sites substantially: Their incoming-to outgoing file rate was usually 1/5. Meaning, each cached file was usually sent out five times during its lifetime in the cache disk.

TRICKLE supported a wide range of delivery methods to the user. Besides the usual email+(UUE, XXE, BTOA, etc.), it could also FTP the files to the user, or use NJE SENDFILE where possible and desired.

It was possible to subscribe to file patterns, such as <MSDOS.VIRUS>SCAN and to have the server deliver you a new copy of the file each time it is made available. A special keyword, '*' could be used instead of the pattern to subscribe to an entire subdirectories, like: <OS2.NEW>*

At its heyday, TRICKLE processed thousands of requests daily, delivering many gigabytes of software to its users.

The server allowed users anywhere around the world to request files from an FTP server on the Internet via a gateway server which was connected to both networks. It was intended to enable the more widespread distribution of (what was then referred to as) Public Domain software from the SIMTEL20 and about a dozen other repositories (hence the command /PDGET, see below).

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