preferred protocol unidirectional SOAP messages

Http is not the best way.

Although a One-Way SOAP message is conceptually unidirectional, but when it's sent over HTTP some type of HTTP reply will be transmitted back to the receiver. One-Way SOAP messages do not return SOAP faults or results of any kind, so the HTTP 202 Accepted response code indicates only that the message made it to the receiver—it doesn't indicate whether the message was successfully processed