[erlang-questions] Distributed publish/subscribe system

[jay@REDACTED]

Kaiduan is looking for a PubSub solution:

> 1) ... support tens to hundreds of millions
> users spreading around the world ...

> 2) ... no limit on the number of subscribers in each group ...

> 3) The number of topics/groups in the system is unlimited.

> 4) User is not always connected to the system...

> 5) ... latency ... of 1 minute if subscriber is connected.

> I am doing research on this topic now, the other requirements
> are not sorted out yet.

CouchDB is a possibility, and you could test it out using
a service such as http://www.cloudant.com/ which uses
quorum reads and writes to ensure data accuracy.  The
requirements I left in above are the ones that Couch would
purport to satisfy, although on the scale of users you
are talking about you would definitely need services
distributed to different continents.

jay