Prashant,
Well the good news is that you can certainly use Flow to build service to perform the PO-related tasks you listed (receive, acknowledge, store, compare and acknowledge more fully).
The bad news is that I can’t tell you how to do that in a discussion forum post (or even in several of them).
It sounds like you need some basic training in webMethods Developer and possibly in webMethods Trading Networks. You can find basic documentation on those products in the \IntegrationServer\Developer\Doc folder or on webMethods Advantage in the Bookshelf section. There is a pretty decent tutorial for webMethods Developer 4.6 that is still very applicable for current releases of Developer. You can also find that document on Advantage.
WMUsers is a great place to ask specific questions about obstacles you may run into. However, we can’t design your integration application for you or teach you how to use the products that you will need.
Mark
#Flow-and-Java-services#webMethods#Integration-Server-and-ESB