[Spread-users] delivery w/ no listener?

John Lane Schultz jschultz at spreadconcepts.com
Tue Feb 20 13:07:10 EST 2007

Spread is an ephemeral messaging system.  Spread delivers a message only to 
those receivers that are directly connected when the message first becomes 
deliverable.  Messages and "group subscriptions" are not persistent.  This means 
that if a receiver crashes (or partitions) it will miss messages sent while it 
is crashed (or partitioned) and Spread will not automatically recover those 
messages for it.

The usual way people address this problem is by having more redundancy in the 
number of receivers performing the same task.

Alternatively, Spread Concepts has a commercial product called Congruity that 
extends Spread to also perform persistent messaging, which ensures that no 
messages are lost due to crashes or partitions.  If you are interested in 
exploring using Congruity in your product, then you can contact us at 
info at spreadconcepts.com.

Congruity: http://www.spreadconcepts.com/replication_info.html


Jim Spath wrote:
> I am wondering what happens to messages received by Spread when there is 
> no listener connected to "receive" the message.
> We want to use Spread for logging various frontend activity to a backend 
> machine from multiple web servers, some or all of which will end up in 
> the database.
> Writing the code to send a message and receive messages is easy enough, 
>  but we are concerned about what happens to these messages if the 
> listener were to crash for whatever reason.  As far as I can tell, these 
> messages are lost, which isn't an ideal solution, as some of these 
> messages are absolutely critical.
> I guess I'd like to know what happens to these messages, and, if they 
> really are "lost", how to best handle the possibility of our Spread 
> listener(s) crashing.  If it matters, we will be using Perl w/ Spread.
> Thanks!
> Jim
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> Spread-users mailing list
> Spread-users at lists.spread.org
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John Schultz
Spread Concepts LLC
Phn: 443 838 2200
Fax: 301 560 8875

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