Thread: Monitor the progress of sending a file to client

I am using a Java module in Wowza server (rtmp protocol) to send a bytearray
to the client application (AS3).
I need to Monitor the download of this file and the client application(AS3) does not allow it: There is a known bug in AS3 that prevents access to the Loader class when uploading certain files, if the loading of the file has not completed.
Would it be possible for the server side Java script to somehow send the client some information about the "sending" of the file ?
Does someone have any other idea how I "help" the client get progress information ?
The Java wowza module is using the following line to send the bytearray:

sendResult(client, params, AMFDataByteArray.wrap(fileBytes));

I will be grateful even for a general answer such as: yes, it can be done and you should use the following mechanism, etc.