You can create a publishable document and publish the document using the developer.
Create a flow service that accepts the published document. Perhaps you retrieve the message from the document and write it to the server log using pub.flow:debugLog.
Create a trigger and point it to the flow you just created. Make sure you specify the full namespace for the document name in the input signature of the flow service.
Cheers.
Ray
#webMethods#Flow-and-Java-services#Integration-Server-and-ESB