When and why is the webMethods Broker used?
This question has been asked and answered recently in this forum. The search function is your friend.
You also might find reading the Publish Subscribe Developer’s Guide to be helpful.
I know your account has been inactive for some time, so you might want to read the “sticky” posts in the New User Introductions forum. The post on how to get help at wMUsers would seem to be appropriate.
Mark