Dear Sunderman,
Thank you for your reply, What I meant here is not the GeoEvent Definition, I will give you an example to more explain my question,
Suppose I have a Csv file output, and the following input
My Definition Schema as follow
TrackID, Speed, XY, DateTime, etc..
Now the output will save the coming input to some file, say AVL2014-1-1.csv
the AVL is the file name prefix,
I just want to make the file name prefix dynamic and it will be taken from the input data, in my case the TrackID.
if I have TrackID=TRC123Y, the the file name will be TRC123Y-2014-1-1.csv
or if I have TrackID=TRC444X, the the file name will be TRC444X-2014-1-1.csv
The prefix of the output file is dynamic and taken from the Input it self.
this will help to find the output data for TrackID TRC123 in one and separate file.