Success Message in CHANGESET_END Method

Hi,

I am new to Gateway. We are currently working on BATCH process. In the BATCH process , i have written some code in the CHANGESET_END method. This method doesn't have the export parameter. It has only exception. The thing is i want to return a variable as export. How can it be achieved.

1. I tried set_header , but it is not working in that method. But it works in all other methods like get_entity , get_entityset etc.

Kindly guid how it can be achieved. I want to return back the invoice number from CHANGESET_END method.

Thanks in advance