durable client after failure?

[Paul Tomsic]

How do i set up a topic such that it has "knowledge"
of who has received what message?
The reason for this, is, say a consumer is grabbing
msgs from topic[a], and gets 1,2,3,4 then dies.
when that consumer reconnects, i don't want it to
re-retrieve 1-4, but rather start at 5 and proceed
from there.
?