[zeromq-dev] publisher side filtering

[Martin Sustrik]

Matt Weinstein wrote:

> Data coloring: Publish on multiple ports, one for each type of data.

Right.

However, this won't work if there's infinite number of topics.

> Crypto: Multicast can go anywhere. If you really have a security  
> issue, you could encrypt the payload and use REQ-REP to get the  
> current keys (and age them out)

Yes. This is the algorithm that makes sense even on Internet scale: 
There can be as many devices in the middle (i.e. distribution tree can 
have as many levels as needed), the devices don't have to be trusted and 
the the delivery still works.

On a different topic: There's definitely a need for forwarding 
subscriptions up the stream in 0MQ (from subscriber to publisher).

As Pieter noted this can be done only for bidirectional transports (TCP, 
inproc and alike), not for uni-directional ones like PGM.

The design for the functionality is ready, the implementation is 
missing. There have been some guys who volunteered for implementing it 
lately, but I haven't heard from them since.

Martin