Ah right, I guess there will be a ZMQ-assigned identity if you don't set
one. Wasn't able to find that in the docs right away though. I found it
in the ZGuide now though. Seems like the ROUTER itself will invent those
for each connected socket that doesn't announce its own identity.
Happy hacking!
Regards,
Patrik
On 14.02.2018 22:40, Jake wrote:
Ok, thanks for the explanation and doc reference. My A node spawns the
B nodes in the
first place, so I guess I can either (1) assign the identity
out-of-band at spawn time and
have the B use it, or (2) have B handshake once at start up to allow A
to associate the
zmq-assigned identity. After that B just receives and sends on
DEALER; without other
sockets connected there is no load balancing on B's end. Node A uses
the identity association
to send to a particular B and to recognize which B is sending when it
receives a message.
-Jake
On Wed, Feb 14, 2018 at 4:25 PM, Patrik Wenger <[email protected]
<mailto:[email protected]>> wrote:
Hi Jake
In fact, most ZMQ socket types do some sort of load balancing when
connected with multiple other sockets. See [1], especially the
"Outgoing routing strategy" and "Incoming routing strategy" in the
table for each socket type. TL;DR if the socket allows receiving
messages and is connected to multiple other sockets, it will try
to read from all of those sockets "fairly". If the socket allows
sending messages and is connected to multiple other sockets, it
will usually round-robin when sending.
Of course PUB (and RADIO) will not round-robin, but "fan out"
instead, meaning all connected sockets will receive every message.
And ROUTER is an exception too: When sending, it uses the first
message part (set by the application) to determine the correct
receiver. This allows you to send a message to one specific
connected socket. When receiving, it prepends a message part that
identifies the socket which sent the message. Your application
will have to inspect that first part to know who is its sender.
These two things will have to happen in your A node. The DEALER
sockets in your B nodes will have to set an identity to be
distinguishable in A's ROUTER socket.
Regards,
Patrik
[1] http://api.zeromq.org/4-2:zmq-socket
<http://api.zeromq.org/4-2:zmq-socket>
On 14.02.2018 20:17, Jake wrote:
Isn't ROUTER-DEALER load balancing though? I've used it in a
REQ-ROUTER-DEALER-REP set up
but in that case the REQ -> ROUTER send does not target a
particular handler on the other side, it
just goes to an arbitrary one and the ROUTER makes sure the reply
goes back to the original sender.
How would my sender (an A node) target a particular B node to
receive a message?
-Jake
On Wed, Feb 14, 2018 at 12:34 PM, Justin Azoff
<[email protected] <mailto:[email protected]>> wrote:
On Wed, Feb 14, 2018 at 12:28 PM, Patrik VV.
<[email protected] <mailto:[email protected]>> wrote:
> Hi
>
> Not sure why Justin suggested using a ROUTER-Socket on each
side.
Ah yes, I misread the original message. For "one-to-many" you
would
use router-dealer. router+router would be more for
many-to-many where
each node runs the same code and there is no obvious master node.
--
- Justin
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