Status of This Memo

This memo describes an Internet background file transfer service that is built upon the third-party transfer model of FTP. No new protocols are involved. The purpose of this memo is to stimulate discussion on new Internet service modes. Distribution of this memo is unlimited.

1 Introduction

For a variety of reasons, file transfer in the Internet has generally been implemented as an interactive or "foreground" service. That is, a user runs the appropriate local FTP user interface program as an interactive command and requests a file transfer to occur in real time. If the transfer should fail to complete for any reason, the user must reissue the transfer request. Foreground file transfer is relatively simple to implement -- no subtleties of queuing or stable storage -- and in the early days of networking it provided excellent service, because the Internet/ARPANET was lightly loaded and reasonably reliable.

More recently, the Internet has become increasingly subject to congestion and long delays, particularly during times of peak usage. In addition, as more of the world becomes interconnected, planned and unplanned outages of hosts, gateways, and networks sometimes make it difficult for users to successfully transfer files in foreground.

Performing file transfer asynchronously (i.e., in "background"), provides a solution to some of these problems, by eliminating the requirement for a human user to be directly involved at the time that a file transfer takes place. A...