[zeromq-dev] zmq fundamental clarification

[Joachim Worringen]

Greetings,

we are considering to use zmq for our very latency-sensitive distributed 
application. zmq offers very compelling features. I searched the web and 
skimmed through the excellent zmq book, but still have some fundamental 
issues:

1. Is there a way to actually send messages in the context of the 
application thread? Something like "direct send" (or call it synchronously).

Background: The additonal hop between the application thread and zmq i/o 
thread add latency and, most of all, jitter esp. on loaded machines. 
Sending the data directly will improve this, esp. with solutions as 
Solarflare/OpenOnload or similar.

The benchmark data in the Wiki with pingpong/2 of around 30us supports 
this, as we certainly target latencies <10us for this kind of test (and 
we do achieve them easily with direct socket access).

2. Does zmq support source-specific multicast?

Background: we do not want to set up and maintain global VLANs between 
our data centers. We are forced into doing this for certain reasons now, 
but it's a PITA and we want to get rid of this.

3. The transparent connection management, and buffering of messages that 
can currently not be sent, is something we need to avoid in certain 
situations. Instead, we'd like to get immediate notification on a failed 
connectione ("remote peer went disconnected"). Is this possible?

thanks, Joachim