Appending the Original File Name as Suffix to Receiver File Name

Question

Been searching and I've seen Michael's blog about creating a UDF to place the original file name in the payload.    Since this is a file->file scenario, I have no mapping. 
I have the Adapter-Specific Attributes turned on on the Sender to pass the file name in the DynamicConfiguration of the message header and I can see it in the message.
What I want to do it to have a target file name in the form of:   XXXXX_<i>originalfilename</i>.
So I have turned on variable substitution and created a variable called 'file'.
In the File Name Scheme Parameter I have entered: XXXXXX_%file%
If I set the variable substitution refererance for 'file' to message:message_id, my file name is created as XXXXX_message_id,  or any of the other options from -> <a href="http://help.sap.com/saphelp_nw04/helpdata/en/bc/bb79d6061007419a081e58cbeaaf28/content.htm">SAP Adapter Help Page</a>
How can I get the value of FileName as the value for my variable %file%?

Answer 1

> Actually, what I meant was the mapping will not know
> the value I have entered in the receiver
> communication channel - File Name Scheme parameter
> value.   For example in CC for Target System 1  the
> FNS = FMRECEIVER1, the CC for Target System 2 the FNS
> = FM_RECEIVER2 and so on.  
>
> Are you saying in the mapping I could access the
> value of FNS from the communication channel in the
> mapping?   
No, you cant read in mapping what you set in CC.
However, you can ignore the parameter FileName scheme in CC and just set it in mapping runtime.
The way you are using, you'll have to maintain the prefix for each receiver adapter you have. If you had it in mapping, you could just do something like:
String receiver = container
    .getTransformationParameters().
    .get(StreamTransformationConstants.SENDER_SERVICE);
DynamicConfiguration conf = (DynamicConfiguration) container
    .getTransformationParameters()
    .get(StreamTransformationConstants.DYNAMIC_CONFIGURATION);
DynamicConfigurationKey key = DynamicConfigurationKey.create(
    “http://sap.com/xi/XI/System/File”,
    “FileName”);
String orgFileName = conf.get(key);
String tgtFileName = receiver + "_" + orgFileName;
conf.put(key, tgtFileName);
and then you wouldn't have to maintain the file name scheme in CC.
Regards,
Henrique.