Did you specify a Content Type in the file polling port definition? If so, the content handler for that type will be used for all files found in the directory.
If no Content Type is specified then IS maps the file extension using MIME types to the appropriate content type and uses that handler. For XML, the service will be passed a node object. For other extensions, you’ll get an input applicable to the corresponding MIME type (there isn’t a mapping for .csv files).
Hope this helps to point in the right direction.
#Flow-and-Java-services#Integration-Server-and-ESB#webMethods