Uttam,
It all depends on how you design the complete solution. On the source side how you are getting the flat files you need to make sure the files from source are following some naming conventions (eg: order.txt )
Ask the business group if this is possible. Then you can use ftp (different server) or file polling (mapped network drive).
For archiving you need to make sure that the file is processed correctly.
Follow the webMethods best practices approach of try/catch.
Many people in this group has implemented solutions around it. Try searching for other posts and see if you could figure it out.
RK
#Flow-and-Java-services#webMethods#Integration-Server-and-ESB