path: root/signaling/high-level-viwi-service.md

# AGL VIWI HIGH-CAN binding architecture

This binding is intended to act between low-level binding(s) and clients. It
builds ViWi resources as defined in a json configuration file. It implements
subscribe/unsubscribe/get verbs for the clients accordingly with protocol
specification.

Each ViWi resource can be composed of several elements, for which subscriptions
will be made to the low-level binding with configurable frequencies or filters.

![ViWi High Level binding architecture](images/high-level-arch.png)

# BRIEF VIWI DESCRIPTION

ViWi (Volkswagen Infotainment Web Interface) protocol defines a serie of
objects, which can be queried or updated via JSon messages.

Each object is assigned with a unique URI.

The depth of the URI tree is limited to 3, i.e.
_/service/resource>/element/_, for instance
**/car/doors/3901a278-ba17-44d6-9aef-f7ca67c04840**.

To retrieve the list of elements for a given resource, one can use the get
command, for instance **get /car/doors/**.

It is also possible to subscribe to elements or group of elements, for
instance **subscribe /car/doors/3901a278-ba17-44d6-9aef-f7ca67c04840**.
Requests can also have various filters, or specify a frequency.

More details in the [ViWi general documentation](https://www.w3.org/Submission/viwi-protocol/)
and in the [ViWi.service.car documentation](https://www.w3.org/Submission/viwi-service-car/)

# Installation

## Prerequisites

Low level CAN service (>=4.0) must be installed. Prerequisites are the same.
Follow instructions from **Low level CAN service Guide**.

```bash
git clone --recursive https://gerrit.automotivelinux.org/gerrit/apps/low-level-can-service
```

## Clone

```bash
export WD=$(pwd)
git clone --recusive https://github.com/iotbzh/high-level-viwi-service.git
```

## Build

Use the classic build flow:

```bash
cd $WD/high-level-viwi-service
mkdir build
cd build
cmake ..
make
```

# Usage

## JSON configuration file

This file must be named *high.json*, and must accessible from afb-daemon.

The json configuration file consists in 2 sections:

### Definitions section

This section describes each resources defined in the high-level binding. Each
resource is composed with different properties having a name, a type and a
description.

Type can be boolean, double, string, or int. Properties "id", "uri" and "name"
are compulsory.

For instance:

```json
{
	"name": "/car/demoboard/",
	"properties": {
		"id": {
			"type": "string",
			"description": "identifier"
		},
		"uri": {
			"type": "string",
			"description": "object uri"
		},
		"name": {
			"type": "string",
			"description": "name"
		},
		"unit": {
			"type": "string",
			"description": "units"
		},
		"speed": {
			"type": "double",
			"description": "vehicle centerpoint speed as shown by the instrument cluster"
		},
		"rpm": {
			"type": "double",
			"description": "engine rotations per minute"
		},
		"level": {
			"type": "double",
			"description": "level of tankage"
		},
		"load": {
			"type": "double",
			"description": "engine load"
		}
	}
}
```

### Resources section

This section defines which values should be assigned to resource's properties
as defined in the definitions section. The link to the definitions section is
made through the name of the resource.

Some values are static, some are linked to low-level requests.

In case a value is linked to a low-level request, the value will start with
"${" and end with "}". In that case the value will consist in the name of the
low-level signal, followed with the frequency of the signal in ms. -1 in the
frequency means that high level binding should subscribe to low level binding
for all changes, without specifying a frequency.

For instance:

```json
{
	"name": "/car/demoboard/",
	"values": [{
		"name": "vehicleSpeed",
		"unit": "km/h",
		"speed": "${diagnostic_messages.vehicle.speed,1000}"
	}, {
		"name": "engineSpeed",
		"unit": "rpm",
		"rpm": "${diagnostic_messages.engine.speed,1000}"
	}, {
		"name": "fuelLevel",
		"unit": "litre",
		"level": "${diagnostic_messages.fuel.level,1000}"
	}, {
		"name": "engineLoad",
		"unit": "Nm",
		"load": "${diagnostic_messages.engine.load,1000}"
	}]
}
```

## Running and testing

### Launch the binder together with the two bindings

The Json high level configuration file *high.json* must be placed in the
directory where you launch afb-daemon.

```bash
cp $WD/high-level-viwi-service/high.json $WD
 cd $WD
```

Then you can natively under linux you can launch afb-daemon with the low-level
and high-level bindings with a command like:

```bash
cd $WD
afb-daemon --rootdir=$WD/low-level-can-service/CAN-binder/build/package --binding=$WD/low-level-can-service/CAN-binder/build/package/lib/afb-low-can.so --binding=$WD/high-level-viwi-service/build/package/lib/afb-high-can.so --port=1234 --tracereq=common --token=1 --verbose
```

### Use afb-client-demo to test high level binding

On another terminal, connect to the binding using previously installed
_**AFB Websocket CLI**_ tool:

```bash
$ afb-client-demo ws://localhost:1234/api?token=1
```

You will be on an interactive session where you can communicate directly with
the binding API.

The binding provides at this moment 3 verbs, _get_, _subscribe_ and
_unsubscribe_, which can take a JSON object as an argument.

To use the _**AFB Websocket CLI**_ tool, a command line will be like the
following:

```
<api> <verb> <arguments>
```

Where:

* API : _**high-can**_.
* Verb : _**get**_, _**subscribe**_ or _**unsubscribe**_
* Arguments : _**{ "name": "/car/doors/" }**_

You can therefore use commands such as:

```
high-can subscribe {"name":"/car/doors/","interval":10000}
high-can unsubscribe {"name":"/car/doors/","interval":10000}
high-can get {"name":"/car/demoboard/"}
high-can get {"name":"/car/demoboard/","fields":["fuelLevel","engineLoad"]}
```

For instance the output of the third command should be:

```
high-can get {"name":"/car/demoboard/"}
ON-REPLY 1:high-can/get: {"response":{"\/car\/demoboard\/2159e2-5b638a-39e242-7a2f5":{"id":"2159e2-5b638a-39e242-7a2f5","name":"vehicleSpeed","speed":0.000000,"unit":"km\/h","uri":"\/car\/demoboard\/2159e2-5b638a-39e242-7a2f5"},"\/car\/demoboard\/22ad2c-5a3c2b-50fabb-324c82":{"id":"22ad2c-5a3c2b-50fabb-324c82","level":0.000000,"name":"fuelLevel","unit":"litre","uri":"\/car\/demoboard\/22ad2c-5a3c2b-50fabb-324c82"},"\/car\/demoboard\/3a3ab9-2bd52c-11d30-689acf":{"id":"3a3ab9-2bd52c-11d30-689acf","name":"engineSpeed","rpm":0.000000,"unit":"rpm","uri":"\/car\/demoboard\/3a3ab9-2bd52c-11d30-689acf"},"\/car\/demoboard\/5ae808-8093cb-99716-30a605":{"id":"5ae808-8093cb-99716-30a605","load":0.000000,"name":"engineLoad","unit":"Nm","uri":"\/car\/demoboard\/5ae808-8093cb-99716-30a605"}},"jtype":"afb-reply","request":{"status":"success","uuid":"44ce03f9-a7ca-49e1-a62a-40c74db0caa0"}}
```

As you can see for the moment all values are 0, because we didn't inject any
CAN data in the binder. To do this, you can use **canplayer** to feed the
bindings with some data.

You can find an example of data in high level binding, "samples" directory.

For instance, on a third terminal:

```bash
$ canplayer -I candata
```