Vehicle App Manifest

Versions

• v1
• v2
• v3 (current)

Introduction

The AppManifest defines the properties of your Vehicle App and its functional interfaces (FIs).

FIs may be:

• required service interfaces (e.g. a required gRPC service interface)
• the used vehicle model and accessed data points.
• an arbitrary abstract interface description used by 3rd parties

In addition to required FIs, provided FIs can (and need) to be specified as well.

These defined interfaces are then used by the Velocitas toolchain to:

• generate service stubs for either a client implementation (required IF) or a server implementation (provided IF) (i.e. for gRPC)
• generate a source code equivalent of the defined vehicle model

Overview

The image below depicts the interaction between App Manifest and DevEnv Configuration at -development time- The responsibilities are clearly separated; the App Manifest describes the application and its interfaces whereas DevEnv Configuration (or .velocitas.json) defines the configuration of the development environment and all the packages used by the Velocitas toolchain.

Context

To fully understand the AppManifest, let’s have a look at who interacts with it:

Purpose

• Define the requirements of a Vehicle App in an abstract way to avoid dependencies on concrete Runtime and Middleware configurations.
• Description of your applications functional interfaces(VehicleModel, services, APIs, …)
• Enable loose coupling of functional interface descriptions and the Velocitas toolchain. Some parts of the toolchain are responsible for reading the file and acting upon it, depending on the type of functional interface
• Providing an extendable syntax to enable custom functional interface types which may not provided by the Velocitas toolchain itself, but by a third party
• Providing a single source of truth for generation of deployment specifications (i.e. Kanto spec, etc…)

Example

// AppManifest.json
{
  "manifestVersion": "v3",
  "name": "SampleApp",
  "interfaces": [
    {
        "type": "vehicle-signal-interface",
        "config": {
            "src": "https://github.com/COVESA/vehicle_signal_specification/releases/download/v3.0/vss_rel_3.0.json",
            "datapoints": {
                "required": [
                    {
                        "path": "Vehicle.Speed",
                        "optional": "true",
                        "access": "read",
                    }
                ],
                "provided": [
                    {
                        "path": "Vehicle.Cabin.Seat.Row1.Pos1.Position",
                    }
                ]
            }
        }
    },
    {
        "type": "grpc-interface",
        "config": {
            "src": "https://raw.githubusercontent.com/eclipse-kuksa/kuksa-incubation/0.4.0/seat_service/proto/sdv/edge/comfort/seats/v1/seats.proto",
            "required": {
                "methods": [ "Move", "MoveComponent" ]
            },
        }
    },
    {
        "type": "pubsub",
        "config": {
            "reads":  [ "sampleapp/getSpeed" ],
            "writes": [ "sampleapp/currentSpeed", "sampleapp/getSpeed/response" ]
        }
    }
  ]
}

The VehicleApp above has an:

• interface towards our generated Vehicle Signal Interface based on the COVESA Vehicle Signal Specification . In particular, it requires read access to the vehicle signal Vehicle.Speed since the signal is marked as optional the application will work, even if the signal is not present in the system. Additionally, the application acts as a provider for the signal Vehicle.Cabin.Seat.Row1.Pos1.Position meaning that it will take responsibility of reading/writing data directly to vehicle networks for the respective signal.

• interface towards gRPC based on the seats.proto file. Since the direction is required a service client for the seats service will be generated who interacts with the Velocitas middleware.

• interface towards the pubsub middleware and is reading to the topic sampleapp/getSpeed and writing the topics sampleapp/currentSpeed, sampleapp/getSpeed/response.

The example has no provided interfaces.

Structure

Describes all external properties and interfaces of a Vehicle Application.

Properties

Interfaces

Properties

Config

The configuration of the functional interface type. Content may vary between all types.

Refer to the JSON Schema of the current AppManifest here .

Visualization

graph TD
    manifest(AppManifest.json)
    manifest --> manifestVersion[manifestVersion]
    manifest --> name[name]
    manifest -.-> interfaces[interfaces]

    interfaces -- "0..n" --> interfaces.item(object)
    interfaces.item --> interfaces.item.type[type]
    interfaces.item -.-> interfaces.item.config[config]

Functional interface types supported by Velocitas

Here is a list of functional interface types directly supported by the Velocitas toolchain and which Velocitas CLI packages are exposing the support:

• Vehicle Signal Interface
• gRPC interface
• Publish and subscribe

Support for additional interface types may be added by providing a 3rd party CLI package .

Planned, but not yet available features

Some FIs are dependent on used classes, methods or literals in your Vehicle App’s source code. For example the vehicle-model FI requires you to list required or provided datapoints. At the moment, these attributes need to be filled manually. There are ideas to auto-generate these attributes by analyzing the source code, but nothing is planned for that, yet.

Further information

• Tutorial: Quickstart
• Tutorial: Vehicle Model Creation
• Tutorial: Vehicle App Development
• Concept: Lifecycle Management