MessageSessionCallback

Starting with Spring Integration version 4.2, you can use a MessageSessionCallback<F, T> implementation with the <int-sftp:outbound-gateway/> (SftpOutboundGateway) to perform any operation on the Session<SftpClient.DirEntry> with the requestMessage context. You can use it for any non-standard or low-level SFTP operation (or several), such as allowing access from an integration flow definition, or functional interface (lambda) implementation injection. The following example uses a lambda:

@Bean
@ServiceActivator(inputChannel = "sftpChannel")
public MessageHandler sftpOutboundGateway(SessionFactory<SftpClient.DirEntry> sessionFactory) {
    return new SftpOutboundGateway(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-sftp:outbound-gateway/> provides a session-callback attribute that lets you specify the MessageSessionCallback bean name.

The session-callback is mutually exclusive with the command and expression attributes. When configuring with Java, the SftpOutboundGateway class offers different constructors.