ZeroMQ

The ZeroMQ node-type exchanges messages via the ZMTP protocol. It is similiar to the nanomsg node-type.

ZeroMQ (also known as ØMQ, 0MQ, or zmq) looks like an embeddable networking library but acts like a concurrency framework. It gives you sockets that carry atomic messages across various transports like in-process, inter-process, TCP, and multicast. You can connect sockets N-to-N with patterns like fan-out, pub-sub, task distribution, and request-reply. It's fast enough to be the fabric for clustered products. Its asynchronous I/O model gives you scalable multicore applications, built as asynchronous message-processing tasks. It has a score of language APIs and runs on most operating systems. ZeroMQ is from iMatix and is LGPLv3 open source.

The ZeroMQ node-type implements the publish/subscribe and radio/dish protocols.

Prerequisites

This node-type requires libzmq (>= 2.2.0).

Implementation

The source code of the node-type is available here: https://git.rwth-aachen.de/acs/public/villas/node/blob/master/lib/nodes/zeromq.cpp

Configuration

format (string)

The payload format which is used to encode and decode exchanged messages.

filter (string: "pubsub" | "radiodish")

publish (string: uri)

subscribe (string / array of strings: uri)

ipv6 (bool) = false

CurveZMQ cryptography

Note: This feature is currently broken.

You can use the villas zmq-keygen command to create a new keypair for the following configuration options:

ipv6 (bool) = false

Whether or not the encryption is enabled.

curve.public_key (string: Z85 encoded)

The public key of the server.

curve.public_key (string: Z85 encoded)

The private key of the server.

Example

nodes = {
        zeromq_node = {
                type = "zeromq"

                pattern = "pubsub"                      # The ZeroMQ pattern. One of pubsub, radiodish
                ipv6 = false                            # Enable IPv6 support

                curve = {                               # Z85 encoded Curve25519 keys
                        enabled = false,
                        public_key = "Veg+Q.V-c&1k>yVh663gQ^7fL($y47gybE-nZP1L"
                        secret_key = "HPY.+mFuB[jGs@(zZr6$IZ1H1dZ7Ji*j>oi@O?Pc"
                }

                in = {
                        subscribe = "tcp://*:1234"      # The subscribe endpoint.
                                                        # See http://api.zeromq.org/2-1:zmq-bind for details.
                        filter = "ab184"                # A filter which is prefix matched for each received msg
                }
                out = {
                        publish = [                     # The publish endpoints.
                                "tcp://localhost:1235", # See http://api.zeromq.org/2-1:zmq-connect for details.
                                "tcp://localhost:12444"
                        ]

                        filter = "ab184"                # A prefix which is prepended to each send message.
                }
        }
}