There are plenty of blogs for using requestresponsebean and responseonewaybean modules to use async sync bridge. You can do it you might have to map the soap response to some psuedo interface at the end. like
file -> SOAP ->file.
If you want to ignore the soap response, you can also do it. Design level you keep the response synchronous... That is file to soap (request mapping) and soap to file (response mapping). But you can configure the soap channel as EO instead of BE to avoid the response (if you dont need). This is an another technique to ignore synchronous response by setting configuration object changes.