COM/OLE Operational Overview

Under normal operation, FileLink reads a script command from a designated file, performs the command, sets a result code that the script may interrogate, and then FileLink reads the next command from the file. The script can make decisions based on the value of the result code and therefore control the course of a file transfer session.

This works great. But as robust as the FileLink script language may be, it still falls short of what can be done using a true programming language like C++ and Visual Basic.

With FileLink in a COM/OLE environment, there is no script file per se. The application program launches FileLink, establishes a named session, and then sends script commands by way of the COM/OLE interface. FileLink performs a command and returns the result code to the application. (The application may block and get the result code when FileLink completes the command, or it may issue the command and continue, and receive the result via an event call. There is never more than a single command pending at one time.)

Upon return, the application program interrogates the result code and determines what to do next. As necessary, more commands are directed to FileLink until the file transfer session is complete -- the session is complete according to the application program's criteria, not FileLink's. At that point, the application closes the session and FileLink terminates.

One of the options when creating a sesson with FileLink is to keep it completely hidden from view so end users see the user-written application, not FileLink. Each session is uniquely named, so it is possible to invoke multiple, independent FileLink sessions.