There are three main communications software programs that I have some experience with. These are FTP, XCOM, and Netmaster FTS.
Netmaster is mostly used on mainframes but a pc version is available. Netmaster uses SNA as a communications channel to transfer files between the systems.
XCOM is a Computer Associates product that is available for MVS, Unix, AS/400, Windows NT, OS/2 and several other operating systems. It uses either SNA or TCP/IP to communicate between the systems. All file transfers via XCOM are logged and transfers can be scheduled to run at a later date and time. The XCOM system will continue to attempt to send a scheduled file transmission until the transmission is either successful or it is cancelled. An inquire facility allows the submitting system to monitor the success of the transmission and to log an error if the transmission has not occurred within a given amount of time.
Almost all operating systems these days come with some basic FTP support and programs are also available to provide enhanced functionality. FTP uses TCP/IP to communicate between systems. FTP itself does not log transmissions and does not have the capability to schedule transmissions to occur at a later time. A single FTP session that is performing multiple transmissions is not able to report the failure of one of the transmissions without also abandoning all of the subsequent transmissions.
This article written by Stephen Chapman, Felgall Pty Ltd.