FreeSWITCH ESL Bindings for Node.js

A Library for handling low-level FreeSWITCH ESLconnections, and associated ESLevents.

API Documentation - API Events - Event Socket Library Spec

Purpose

This library was written to implement the full Event Socket Library interface, and provide a meaningful semantic when dealing with FreeSWITCH in Node.js.

This library supports both "Inbound" (connection going into FreeSWITCH) and "Outbound" (connections coming out of FreeSWITCH). Also included is a helper Server object that manages multiple Connection objects; making it trivial to have multiple "Outbound" connections from FreeSWITCH.

Installation

The easiest way to install is via npm:

npm install modesl

As in "Mod ESL".

Usage

The most basic usage example is to open a connection, and send a status command:

const esl = require('modesl');

const connectionOptions = {
    host: '127.0.0.1',
    port: 8021,
};
const connection = esl.Connection.createInbound(connectionOptions, 'ClueCon', function ()
{
    connection.api('status', function (res)
    {
        console.log(res.getBody());
    });
});

Something to be aware of is that all functions that interact with FreeSWITCH are asynchronous on the Library side. However, there are many functions (api, execute, etc) that are synchronous on the FreeSWITCH side. Because of this the event you will get back in your callback on, for example, api and the same command on bgapi will be different.

The api command's callback will be executed immediately when the command/reply message is received, with all the returned data. However, that same command using bgapi will not call the callback when the command/reply message is received, this is because FreeSWITCH returns the command/reply message immediately for background commands before the command is run. The Library will automatically track the command, and call the callback on the BACKGROUND_JOB message that denotes a completed Background Job.

The body for the same command issued with api and bgapi should be the same; even when the headers, event type, and time it takes for the callback to execute are different. The Library attempts to smooth these differences out by providing a common interface, even though behind the scenes things are quite different.

License

This module is distributed under the MIT License.