FXP Server To Server

API

• TransferFile()

• TransferDirectory()

Settings

• FXPDataType - Controls if the FXP server-to-server file transfer API uses Binary or ASCII mode. Default: Binary.

How does FXP server to server transfer work?

FXP works by creating a data connection between two FTP servers. FluentFTP can then instruct the source server to start transferring the file and instruct the target server to receive and store it.

You need to call the API in this order:

1. You need to create an FtpClient instance and connect to the source server
2. You need to create an FtpClient instance and connect to the target server
3. Call source.TransferFile or source.TransferDirectory on the source FTP client and provide the target server's FtpClient to make an FXP connection between them

How does FXP server to server transfer work internally?

The order of FTP commands is as follows:

1. We connect to the source server
2. We clone the connection of the target server and reconnect to it
3. Internally, we open a passive FXP connection between the source server and target server by calling OpenPassiveFXPConnection()
4. We maintain an FtpFxpSession object used to track the active FXP connection between 2 servers
5. Internally, we instruct the source server to send the file, using the RETR FTP command
6. Internally, we instruct the target server to store the file, using the STOR FTP command
7. If there are any connection issues, we resume transfer by instructing the source server to resume using REST and RETR FTP command and the target server to store append the file using APPE FTP command
8. We can only check the file transfer progress by constantly sending the SIZE command on the target server to check how many bytes have transferred
9. At the end of transferring the file we optionally verify the file using any mutually supported hash method and then call GetChecksum() on the source and target server and check if the hash matches
10. Finally, we disconnect from source and target servers and the FtpFxpSession is disposed off