Using `MessageSessionCallback`

Starting with Spring Integration 4.2, you can use a MessageSessionCallback<F, T> implementation with the <int-ftp:outbound-gateway/> (FtpOutboundGateway in Java) to perform any operations on the Session<FTPFile> with the requestMessage context. It can be used for any non-standard or low-level FTP operations and allows access from an integration flow definition and functional interface (Lambda) implementation injection, as the following example shows:

@Bean
@ServiceActivator(inputChannel = "ftpChannel")
public MessageHandler ftpOutboundGateway(SessionFactory<FTPFile> sessionFactory) {
    return new FtpOutboundGateway(sessionFactory,
         (session, requestMessage) -> session.list(requestMessage.getPayload()));
}

Another example might be to pre- or post-process the file data being sent or retrieved.

When using XML configuration, the <int-ftp:outbound-gateway/> provides a session-callback attribute to let you specify the MessageSessionCallback bean name.

The session-callback is mutually exclusive with the command and expression attributes. When configuring with Java, different constructors are available in the FtpOutboundGateway class.

Using MessageSessionCallback

Using `MessageSessionCallback`