[Spread-users] Agreed Order

David Ward dward at revasystems.com
Mon Jun 21 12:10:00 EDT 2004


If I were to start using Spread I would be depending heavily on the ordered
delivery feature.  In order to give me confidence, can you help me understand
in general terms how this is implemented?

I assume after reading the documentation that ordered delivery is supported
in configurations where there is one Spread daemon per node.  True?

Assuming one daemon per node...

To summarize ordered delivery - it says that if a group contains nodes A,
B, and C, then if simultaneously A, B, and D (a non-member) send to the
group, then A, B, and C will receive the same messages in the same order.

Does the ordered delivery rely strictly on time being synchronized among
the nodes, and time stamps appended to the packets?  Or are there sequence
numbers used as well somehow?  Can you give me a feel for the techniques used?

What performance overhead is associated with the ordered delivery feature in
particular (say vs the same thing without ordered delivery)?

Thank you,
Reva Systems

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