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ZeroMQ

The zeromq node-type exchanges messages via the ZMTP protocol. It is similar 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://github.com/VILLASframework/node/blob/master/lib/nodes/zeromq.cpp

Configuration​

Format Object (object) or Format Name (string) (format_spec)
destinations
Array of strings <uri> [ items <uri > ]

During startup connect to those WebSocket servers as a client.

Each URI must use the following scheme:

protocol://host:port/nodename

It starts with a protocol which must be one of ws (unencrypted) or wss (SSL). The host name or IP address is separated by ://. The optional port number is separated by a colon :. The node name is separated by a slash /.

object (Input configuration (received by VILLASnode))
vectorize
integer
Default: 1

This setting allows to send multiple samples in a single message to the destination nodes.

The value of this setting determines how many samples will be combined into one packet.

Array of Hook Object (object) or Hook Name (string) (hook_list)
builtin
boolean (Builtin hook functions)
Default: true

By default, each node and paths has a couple of default hooks attached to them. With this setting the attachment of built-in hooks can be disabled.

object (Output configuration (sent out by VILLASnode))
{
  • "format": "villas.human",
  • "destinations": [],
  • "in": {
    },
  • "vectorize": 1,
  • "hooks": [
    ],
  • "builtin": true,
  • "out": {
    }
}

Example​

node/etc/examples/nodes/zeromq.conf
nodes = {
    zeromq_node = {
        type = "zeromq"

        # The ZeroMQ pattern. One of pubsub, radiodish
        pattern = "pubsub"

        # Enable IPv6 support
        ipv6 = false

        # Z85 encoded Curve25519 keys
        curve = {
            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 = {
            # The subscribe endpoint
            # See http://api.zeromq.org/2-1:zmq-bind for details
            subscribe = "tcp://*:1234"

            # A filter which is prefix matched for each received msg
            filter = "ab184"
        }
        out = {
            # The publish endpoints
            # See http://api.zeromq.org/2-1:zmq-connect for details
            publish = [

                "tcp://localhost:1235",
                "tcp://localhost:12444"
            ]

            # A prefix which is pre-pended to each message
            filter = "ab184"
        }
    }
}