replication

Guys,
I am new to MS SQL server replication. As of now, I am trying to spec thngs
out. What is the difference between Multiple Publisher/Multiple subscriber
scenario and Updating Subscriber scenario? Both seem to me as a Sybase DBA
as Multiple master scenario as both have the same data and replication
happens both ways(two way replication). Also, In the Updating subscriber
scenario, server A is sending data to server B via the distribution server
but server B is sending data to server A via a SQL server Queue(Queue Reader
Agent). Why is the subscriber not sending data back to the publisher via the
distribution server? Also, what is the difference between immediate
updates and queued updates? As far as I can understand everything has to
be queued in order to send them to the other side.
Can someone please answer my questions?
Regards
Jaideep
Jaideep,
as a bit of background...
In normal transactional replication, an inserted record on the subscriber
will be replicated to the subscriber via the distribution database
(MSrepl_commands: use sp_browsereplcmds to view them). This is unidirectional
only. For queued updating subscribers the data flow is bi-directional, and
data changes are stored in a table on the subscriber (use sp_replqueuemonitor
to read this MSreplication_queue table). It has to be this way, because the
queue is available for offline access - ie there is the posibility that the
subscriber won't be able to access the publisher\distributer. In the case of
immediate updating subscribers the flow is again bidirectional, but there is
no need to save the command anywhere, because the subscriber enters a
distributed transaction.
I hope this clears up any confusion.
Regards,
Paul Ibison, SQL Server MVP