How to upload via SFTP with allow_url_open disabled?

I'm attempting to send a file over SFTP in PHP, but all the examples I find
online do something like this:

   $stream = @fopen("ssh2.sftp://xxxxxxxxxxxxxxxxxx", 'w');
   @fwrite($stream, $data_to_send)

This requires "allow_url_fopen" to be enabled on the server, to get a stream
for the remote file.

I maintain the server but would like to keep "allow_url_fopen" disabled. If
I do that, how can I send a file over SFTP?

Thanks for any help people can provide!!

Scott Teresi