Well, it might not be the best way to do it, but here’s a way I found to send binary data via PHP’s SOAP extension from one place to another:

Server:

function recieveFile($data){
	$data=base64_decode($data);
	$path='/my/file/path/img_out.gif';
	$fp=fopen($path,'w+');
	if($fp){ fwrite($fp,$data); fclose($fp); }

	return strlen($data).' written';
}
$input	= file_get_contents("php://input");
$server = new SoapServer(
	'http://[my url here]/binary.wsdl',
	array('encoding'=>'ISO-8859-1')
);
$server->addFunction('recieveFile');
$server->handle();

and the Client:

ini_set("soap.wsdl_cache_enabled", "0");

//send binary data
$client=new SoapClient(
	'http://[my url here]/binary.wsdl',
	array('encoding'=>'ISO-8859-1')
);

$data=file_get_contents('/my/file/path/img_to_send.gif');
$ret=$client->recieveFile(base64_encode($data));
print_r($ret);

It’s pretty basic – the client just reads in the file’s information, runs it through a call to base64_encode before it’s sent off to the server. Once it’s there a mirror call to base64_decode gets the content back to normal and it’s written out to the “img_out.gif” file on the remote server.

It’s probably not the best way to do it, but its one that I’ve found that works quickly and easily. I tried to just send the binary data without base64 encoding it and it didn’t want to cooperate (it was only getting the first chunk of data). I don’t know how well it’ll perform with larger files, though – we shall see.