dynamically create directories with file:outbound-channel-adapter

I am writing an application that handles messages coming in thru a webservice. For auditing all incoming messages have to be saved to disk. Because a potential large amount of messages will be handled, and they should be easily found back later, I would like to be able to save my messages into different directories based on the date.

Currently I can set a filename per message. In addition to that I would like to be able to set a directory relative to the base-directory specified in the outbound-channel-adapter. If this directory doesn't exist, it should be created.

To remain backwards compatible I image the filename header can contain a String - use the current behaviour - or a File - use the proposed behaviour.

In addition, the FilenameGenerator should be enhanced to be able to return a full (relative) path.