[Spread-users] reliable messages

Glenn McAllister glenn at somanetworks.com
Fri Jun 6 09:37:43 EDT 2008

Torsten Curdt wrote:
> On Jun 2, 2008, at 11:21, Torsten Curdt wrote:
>> Hey there,
>> While the general concept of spread is great I am wondering about a 
>> few details.
>> What happens if a box drops out of the spread ring due to a crash or 
>> physical problem. What does that mean to the fact that some boxes in 
>> the ring are sending "reliable messages". I doubt that that box will 
>> get all the messages when it comes back online? Who would cache the 
>> messages if so?

There is no caching.  The daemons are responsible for delivery to clients, with 
the given reliability semantics.  If you want something to cache messages and 
send them to new members of a group (your dead daemon comes back and members 
have connected to it, then joined a group), you need to implement that yourself.

When a daemon drops out of the ring, the other daemons will detect this and form 
a new "ring."  Clients in the new ring that were joined to groups that had 
members from the dead box will receive a membership change message.  If I recall 
correctly, any reliable messages sent from the (now) dead client before the 
daemon died will be delivered before the membership change message.  If I don't 
recall correctly, I'm sure someone will quickly point out my error. :-)

>> Also I am wondering about the project's state. It has been a while 
>> since the last release.
> No one here to answer? That sort of answers the last question :(

I think you haven't received much support so far because everything you've asked 
is (I believe) covered in the docs and in the mailing list archives.

I'd argue that the project is quite stable, and has been for years.  There are 
commercial products built off of spread (http://spreadconcepts.com/), and the 
development team are quick to respond to bug reports or requests for help in 
figuring out what spread is doing in edge cases.

Glenn McAllister     <glenn at somanetworks.com>      +1 416 348 1594
SOMA Networks, Inc.  http://www.somanetworks.com/  +1 416 977 1414

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