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Short Description
Asterisk REST Interface proxy for connections over a message bus. Written in Go.
Full Description

go-ari-proxy


An implementation of the [go-ari-library][1] used to connect to the Asterisk
REST Interface for delivery of Events and Commands across a message bus.

  • publishes Events from ARI websocket to a remote client via message bus
  • consumes Commands from a client using a message bus and POSTs them to Asterisk
  • publishes Command responses back onto the message bus for the client

Overview

The go-ari-proxy is an application that makes it easier to build
external applications for the Asterisk REST
Interface (ARI). Primarily, we wrap the ARI messages in a structure that can be
easily disseminated and sent across a message bus using json. From there, the
application can decapsulate the message, act on the ARI portion, and send back a
response in a similar manner.

Installation

$ cd $GOPATH/src
$ go get github.com/nvisibleinc/go-ari-library
$ git clone https://github.com/nvisibleinc/go-ari-proxy
$ go install go-ari-proxy

Configuration

Add a config.json file to your directory you're running the application from.

{
    "origin": "http://foo.com",
    "server_id": "bar",
    "applications": [
        "foo"
    ],
    "websocket_url": "ws://localhost:8080/ari/events",
    "stasis_url": "http://localhost:8080/ari",
    "ws_user": "user",
    "ws_password": "secret",
    "message_bus": "RABBITMQ|NATS",
    "bus_config": {
        "url": "",
        "queue": ""
    }
}
  • origin - A HTTP URI of the Origin (it would normally be sent from a browser)
  • server_id - Unique server identity
  • applications - Array of ARI applications to listen for
  • websocket_url - Websocket URL to connect to
  • stasis_url - Base URL of ARI REST API
  • ws_user - username of websocket/API connection
  • ws_password - password of websocket/API connection
  • message_bus - Type of message bus to use. Options are RABBITMQ and NATS
  • bus_config - An Object containing config for the message bus
    • url - URI of the message bus
    • queue - An option only for NATS, which queue to connect to

Docker Container

TODO

How It Works

The go-ari-proxy application works by using a message bus (NATS, RabbitMQ) and
having a broadcast channel (topic, queue) that applications listen to. When a
StasisStart is recieved by the proxy, we perform an AppStart which
broadcasts this information.

The message bus then distributes this to an application listening on the topic.
From there, the application knows what topic to subscribe to in order to
continue the conversation. Currently this setup channel is unidirectional,
however in the future it may be further enhanced/designed to allow for
applications to acknowledge setup of a dialog.

The primary purpose of the broadcast channel is to distribute to one or more
application instances, and then a dialog is created over three (3) additional
topics. These topics are: Events, Commands, and CommandResponses.

NOTE: Prior revisions of the go-ari-library upon which this proxy is built had
support for the NSQ message bus. Unfortunately, as a result of the eventually
consistent semantics of NSQ's topic discovery mechanism, its use is no longer
supported and the code was removed.

Application topic

  1. proxy starts up and connects to the websocket
  2. proxy connects to the signalling topic, named for the application (configured
    via JSON)
  3. applications connect to same signalling topic based on their configuration
  4. the message bus distributes messages in a round-robin fashion to application
    (message bus dependent)

Dialog topic

  1. on StasisStart event, the proxy creates a new ProxyInstance, creating a
    unique dialogID, and connect to three new topics
  2. On new dialog setup, the proxy sends a new AppStart event across the
    signalling channel to tell the application which topics to listen for Events,
    to send Commands, and to listen for Command Responses.

Application topic distribution

Licensing

Copyright 2015-2016 N-Visible Technology Lab, Inc.

Licensed under the Apache License, Version 2.0 (the “License”); you may not
use this file except in compliance with the License. You may obtain a copy of
the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations under
the License.

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nvisibleinc
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