Awesome

Roon API for Javascript: An overview and tutorial

JSDoc Documentation: https://roonlabs.github.io/node-roon-api/

Getting started

This Roon API for Javascript is called node-roon-api, because it has complete functionality in the Node.js environment, but it also works in a web browser.
Install Node.js from https://nodejs.org/.
- On Windows, install from the above link.
- On Mac OS, you can use homebrew to install Node.js.
- On Linux, you can use your distribution's package manager, but make sure it installs a recent Node.js. Otherwise just install from the above link.
Make sure you are running node 5.x or higher.
```
node -v
```
For example:
```
$ node -v
v5.10.1
```

Create a new extension folder

mkdir roon-extension-test
cd roon-extension-test

Initialize your package.json file and install the dependencies:

cat << EOF > package.json
{
    "name": "roon-extension-test",
    "version": "1.0.0",
    "description": "Roon Extension to test using Roon API",
    "main": "app.js",
    "author": "Elvis Presley",
    "license": "Apache-2.0",
    "dependencies": {
        "node-roon-api": "github:roonlabs/node-roon-api"
    }
}
EOF

npm install

Create an app.js file in with the following contents:

var RoonApi = require("node-roon-api");

var roon = new RoonApi({
    extension_id:        'com.elvis.test',
    display_name:        "Elvis's First Roon API Test",
    display_version:     "1.0.0",
    publisher:           'Elvis Presley',
    email:               'elvis@presley.com',
    website:             'https://github.com/elvispresley/roon-extension-test'
});

roon.init_services({});

roon.start_discovery();

Run it!
```
node .
```
This extension does nothing right now, but it should appear in Roon now. See Settings->Setup->Extensions and you should see it in the list. If you have multiple Roon Cores on the network, all of them should see it.

Connecting to a Roon Core

The extension must declare it's own information using the RoonApi constructor. When your extension connects to Roon, it will register itself with this information.

Roon extensions are meant to discover Roon Cores, to avoid having to have the end user point them at a running Roon Core via IP address. RoonApi::start_discovery() will start watching for any Roon Cores that might be running on the network, and will connect to them automatically.

If the extension uses any services from Roon (note that our test extension above does not use any services), those services must be granted access by the user by hitting "Enable" in Roon's Settings. If it uses no services, then Roon will auto-authorize the extension.

Once the extension has been authorized (or auto-authorized), Roon will pass back a token that represents that authorization. The Roon API will automatically persist this across runs.

If Roon previously authorized the extension, the token is passed and Roon will validate that the authorization still exists.

Your extension can be connected to multiple Roon Cores at once, but if your extension really wants to be connected to only 1 Roon Core, then you should using the pairing functionality.

Services

Roon extensions can use and/or provide services. This works a bit differently than most APIs out there.

Using a service is probably what one first thinks of when using the Roon API. If an extension wants to tell Roon to change the volume or pause the music, it will use the transport service that Roon provides.

Providing a service is when an extension tells Roon that it has some functionality it can provide, and if Roon desires, it can use it.

Services provided by Roon, and used by an extension include:

browsing

This service let's an extension browse Roon's music library (and more) in a simple list orient manner, and even do common actions like play music.
image downloading

This service let's an extension download an image related to artist photos, album artwork, or other images in the Roon databases.
transport

This service let's an extension manage and control zones. This includes actions such as zone grouping, transport controls (play, pause, next, prev, etc...), volume control, standby, etc...
more...

Services provided by an extension and used by Roon:

ping

The Node.js Roon API automatically provides this API. Roon will notice this and periodically ping the extension over the network to make sure the extension is available. This helps Roon provide a better experience on less than ideal networks.
status

Implementing this service in an extension enables it to be able to provide a small status message to Roon about the status of the extension.

Roon will display this status along with the information about the extension in the extensions listing inside Roon Settings.

For example, the Roon extension for the Griffin Powermate USB knob will let Roon know if the USB device is plugged in or not plugged in using this service.
settings

Many extensions will want to have some simple actions and/or configuration. Roon can use a settings service provided by an extension to display a UI inside the Roon Settings screens that is defined by the extension.
volume control and source control

Audio devices that are Roon Ready, allow Roon's user interface on all remotes to send volume commands directly to the hardware, for the most accurate and high quality volume control. Roon will also convenience switch the inputs of Roon Ready devices with multiple source inputs, and support standby functionality in-app.

However, if you have a device that is not Roon Ready, then providing these two services in your extension can allow you to enable this functionality to Roon via Serial/RS232, Infrared, network, or some other mechanism, without hardware Roon support.

Pairing

Most extensions that use services will want to communicate with one Roon Core at a time.

Pairing works by allowing all Roon Cores on the network to show the extension in the Settings, but only one Roon Core can be "paired" to the extension.

For example, the Roon extension for the Griffin Powermate USB knob is an extension that modifies the volume of a zone when a USB knob is rotated. If you ran this extension on a network with multiple Roon Cores, it wouldn't know which Roon Core to control.

With pairing, initial authorization of the extension will automatically pair that Roon Core with this extension. Future connections to the same Roon Core will auto-pair. If you then click 'Enable' on a second Roon core, the pairing will change to the second Roon Core and the knob will begin to control it instead. If you then look at the first Roon Core, the authorization still exists, but instead of seeing an "Enable" button, the user will see a "Pair" button, which will move the pairing back to the first Roon Core.

On a network with 1 Roon Core, this pairing mechanism is very simple and completely transparent to the user. But on a network with multiple Roon Cores, it provides a mechanism that is easy to use, while relieving the extension author of the responsibility of having to create a user interface to select a Roon Core.

Providing a service

Let's make our test extension report a status to Roon.

Make sure your package.json file's dependencies section looks like this now:

"dependencies": {
    "node-roon-api":        "github:roonlabs/node-roon-api",
    "node-roon-api-status": "github:roonlabs/node-roon-api-status"
}

and be sure to install the module:

npm install

Let's modify the app.js to provide the status service.

var RoonApi       = require("node-roon-api"),
    RoonApiStatus = require("node-roon-api-status");

var roon = new RoonApi({
    extension_id:        'com.elvis.test',
    display_name:        "Elvis's First Roon API Test",
    display_version:     "1.0.0",
    publisher:           'Elvis Presley',
    email:               'elvis@presley.com',
    website:             'https://github.com/elvispresley/roon-extension-test',
});

var svc_status = new RoonApiStatus(roon);

roon.init_services({
    provided_services: [ svc_status ]
});

svc_status.set_status("All is good", false);

roon.start_discovery();

The provided_services field when calling the RoonApi::init_services() let's Roon know you have are providing service. Above, we pass an instance of RoonApiStatus, which enables Roon to show a status message below the extension information in Roon Settings.

The RoonApiStatus::set_status() method notifies the connected Roon Cores know of the new status. The second argument is true if the status is an error, and false if it is neutral or good.

Using a service

Let's make our test extension list all the zones.

Make sure your package.json file's dependencies section looks like this now:

"dependencies": {
    "node-roon-api":           "github:roonlabs/node-roon-api",
    "node-roon-api-status":    "github:roonlabs/node-roon-api-status",
    "node-roon-api-transport": "github:roonlabs/node-roon-api-transport"
}

and be sure to install the module:

npm install

Let's modify the app.js to use the transport service.

var RoonApi          = require("node-roon-api"),
    RoonApiStatus    = require("node-roon-api-status"),
    RoonApiTransport = require("node-roon-api-transport");

var roon = new RoonApi({
    extension_id:        'com.elvis.test',
    display_name:        "Elvis's First Roon API Test",
    display_version:     "1.0.0",
    publisher:           'Elvis Presley',
    email:               'elvis@presley.com',
    website:             'https://github.com/elvispresley/roon-extension-test',

    core_paired: function(core) {
        let transport = core.services.RoonApiTransport;
        transport.subscribe_zones(function(cmd, data) {
                                      console.log(core.core_id,
                                                  core.display_name,
                                                  core.display_version,
                                                  "-",
                                                  cmd,
                                                  JSON.stringify(data, null, '  '));
                                  });
    },

    core_unpaired: function(core) {
                   console.log(core.core_id,
                           core.display_name,
                           core.display_version,
                           "-",
                           "LOST");
               }
});

var svc_status = new RoonApiStatus(roon);

roon.init_services({
    required_services: [ RoonApiTransport ],
    provided_services: [ svc_status ],
});

svc_status.set_status("All is good", false);

roon.start_discovery();

In addition to providing the status service, we also specify here that we require the transport service.

Additionally, you see above that the RoonApi constructor can be passed core_paired and core_unpaired members, which will be called when Roon Cores are paired or unpaired.

When you get a hold of a core, you can use the transport service's functionality via core.services.RoonApiTransport.

In this example, we subscribe to the zone listing and print the subscription messages sent to us from the Roon Core. This will print a list of zones at subscription time, and any modification to the zones listing that happen while we are connected.

Working with multiple Roon Cores

In the above examples, the extension provided the core_paired function to get access to the Roon Cores that it was paired with.

When you provide core_paired and core_unpaired, you are notified only of the Roon Core you are paired with.

If you want to be notified of all the Roon Cores, and disable the pairing functionality, you can provide core_found and core_lost instead.

Those functions will be called with every Roon Core discovered (after the extension is authorized or auto-authorized), and no "Pair" button will ever be shown by Roon.

Normally, you don't want to use core_found and core_lost, and instead you want to use Roon API's pairing functionality.

Using Roon API in a Web Browser

The Roon API for Javascript uses web browser friendly networking to speak to Roon, so the API works inside a web browser like Chrome, Safari, IE, and FireFox.

The big exception in functionality is discovery. Roon's discovery protocol uses UDP networking packets, and the web browsers don't have access to that. To get around this, instead of using RoonApi:start_discovery(), you can use RoonApi::ws_connect({ host, port, [onclose] }). You will have to pass the IP address or hostname, plus the websocket port of your Roon Core to this method, and optionally you can pass a callback to call upon disconnection (for retrying the connection). Unfortunately, this means your web app will probably need an input for the IP address of the Roon Core.

The best way to use this API is to use a bundler (like parcel or browserify or webpack) to combine your html/js/css and the entire Roon API into 1 large javascript file.

For an example, see the web test app.