Gopi,
in a map, I don't think you have direct access to the incoming document size. Here are the options as I see them:
– use a functoid to somehow get the file size (details depend on your app)
– use a pipeline component to inject the size of the file into the XML of the message (you need to have a suitable field in the incoming message schema
– get the information in an orchestration and inject it into the XML. You could pass the XML out to an assembly which could get the size and inject it for you.
John D.