Tasks of Class StringInputStream:
This is a Low Memory Implementation to convert a String in a InputStream
It converts only CHAR_BUFFER_SIZE chars at once
Tasks of Interface Transferable:
A Transferable is a Object, wich is Transported between the Backend and Frontend of the System
It holds a PayLoad wich could be writen to different DCPs
It holds a Set of TransferAttributes, wich describe the special aspects of the payload,
or holds other special Information for different DCPs