Advanced Messaging & Queuing Protocol (AMQP)

The amqp node-type exchanges messages over the AMQP protocol with a broker such as RabbitMQ.

A typical publish/subscribe pattern is used: The node automatically declares a direct exchange and dedicated queues for each subscriber.

Prerequisites

This node-type requires rabbitmq-c (>= 0.8.0).

Implementation

The source code of the node-type is available here: https://github.com/VILLASframework/node/blob/master/lib/nodes/amqp.cpp

Configuration

	Format Object (object) or Format Name (string) (format_spec)
uri	string <uri> See also: https://www.rabbitmq.com/uri-spec.html
exchange	string The name of the AMQP exchange the node will publish the messages to.
routing_key	string The routing key of published messages as well as the routing key which is used to bind the subcriber queue.
	object Note: These settings are only used if the uri setting is using the amqps:// schema.
	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",
• "uri": "http://example.com",
• "exchange": "string",
• "routing_key": "string",
• "ssl": {

  • "verify_hostname": "true,",
  • "verify_peer": "true,",
  • "ca_cert": "/path/to/ca.crt",
  • "client_cert": "/path/to/client.crt",
  • "client_key": "/path/to/client.key"

  },
• "in": {

  • "signals": [

    • {

      • "name": "tap_position",
      • "type": "integer",
      • "init": 0

      },
    • {

      • "name": "voltage",
      • "type": "float",
      • "unit": "V",
      • "init": 230

      }

    ],
  • "vectorize": 1,
  • "hooks": [

    • "print",
    • {

      • "type": "limit_rate",
      • "rate": 1000

      }

    ]

  },
• "vectorize": 1,
• "hooks": [

  • "print",
  • {

    • "type": "limit_rate",
    • "rate": 1000

    }

  ],
• "builtin": true,
• "out": {

  • "vectorize": 0,
  • "hooks": [

    • "print",
    • {

      • "type": "limit_rate",
      • "rate": 1000

      }

    ]

  }

}

Example

node/etc/examples/nodes/amqp.conf

nodes = {
    amqp_node = {
        type = "amqp"
        format = "json"

        # Use 'amqps://' to enable SSL/TLS
        uri = "amqp://username:password@example.com:1234/vhost"

        # Alternatively connection settings can be specified individually
        username = "guest"
        password = "guest"
        host = "localhost"
        vhost = "/"
        port = 5672

        exchange = "mytestexchange"
        routing_key = "abc"

        ssl = {
            verify_hostname = true
            verify_peer = true

            ca_cert = "/path/to/ca.crt"
            client_cert = "/path/to/client.crt"
            client_key = "/path/to/client.key"
        }
    }
}