Eclipse Kuksa™ Databroker

Kuksa Databroker is a gRPC service acting as a broker of vehicle data / data points / signals.
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Table of Contents

1. Intro
   • Features
2. Getting Started
   • Prerequisites
   • Starting Databroker
   • Reading and writing VSS data using the CLI
   • Usage
   • Building
   • Contributing
   • License
   • Contact

Intro

The COVESA Vehicle Signal Specification (VSS) defines the names and semantics of a large set of data entries that represent the current and/or intended state of a vehicle's sensors and actuators organized in a tree-like structure. For example, the vehicle's current speed is represented by the Vehicle.Speed entry.

However, VSS does not define how these signals are to be collected and managed within a vehicle, nor does it prescribe how other components in the vehicle can read or write signal values from and to the tree.

Kuksa Databroker is a resource efficient implementation of the VSS signal tree and is intended to be run within a vehicle on a microprocessor based platform. It allows applications in the vehicle to interact with the vehicle's sensors and actuators using a uniform, high level gRPC API for querying signals, updating values of sensors and actuators and getting notified about changes to signals of interest.

flowchart LR
    A[Application] --VSS--- DB
    DB[Kuksa Databroker] --VSS--- P
    P[Kuksa provider] --CAN frames etc---E
    E[ECU] --- Sensor
    E --- Actuator
    style DB fill:#999999,stroke:#444444,color:#ffffff

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At the right end, Kuksa providers implement the link between the Databroker and a vehicle's Electronic Control Units (ECU) to which the hardware sensors and actuators are physically attached.

Data is usually exchanged with ECUs by means of a CAN bus or Ethernet based protocols like SOME/IP. Providers translate between the low level messages used by these protocols and the Databroker's high level gRPC API calls to update a sensor's current reading or to forward a set-point value to an actuator via its controlling ECU.

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Features

• 100% Open Source (Apache 2.0 license)
• Written in Rust with an easy-to-use language agnostic gRPC interface
• Lightweight (<4 MB statically compiled), allowing it to run on even small vehicle computers

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Kuksa analysis

Extended Kuksa analysis containing functional requirements, use cases diagrams, latest and new API definition kuksa.val.v2 as well as new design discussions for future developments and improvements.

APIs supported by Databroker

Kuksa Databroker implements the following service interfaces:

• Enabled on Databroker by default kuksa.val.v2.VAL (recommended to use)
• Enabled on Databroker by default kuksa.val.v1.VAL
• Disabled on Databroker by default sdv.databroker.v1.Broker
• Disabled on Databroker by default sdv.databroker.v1.Collector

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Getting started

The quickest possible way to get Kuksa Databroker up and running.

📝 Note: The examples in this section do not use TLS nor access control. Please refer to the User Guide for more sophisticated usage examples.

Prerequisites

• Docker Engine or Podman
• A custom Docker bridge network

  docker network create kuksa

Starting Databroker

1. Start Databroker in a container attached to the kuksa bridge network using hostname Server:

   docker run -it --rm --name Server --network kuksa ghcr.io/eclipse-kuksa/kuksa-databroker:main --insecure

   💡 Tip: You can stop the container using ctrl-c.

Note that not all APIs are enabled by default, see user guide and protocols for more information!

Reading and writing VSS data using the CLI

1. Start the CLI in a container attached to the kuksa bridge network and connect to the Databroker container:

   The databroker supports the lastest new API kuksa.val.v2 and kuksa.val.v1 by default, sdv.databroker.v1 must be enabled using --enable-databroker-v1. Per default the databroker-cli uses the kuksa.val.v1 interface, which can be changed by supplying the --protocol option when starting. Choose either kuksa.val.v1 or sdv.databroker.v1, as databroker-cli still does not support kuksa.val.v2.

   # in a new terminal
   docker run -it --rm --network kuksa ghcr.io/eclipse-kuksa/kuksa-databroker-cli:main --server Server:55555

   The CLI provides an interactive prompt which can be used to send commands to the Databroker.

     ⠀⠀⠀⢀⣤⣶⣾⣿⢸⣿⣿⣷⣶⣤⡀
     ⠀⠀⣴⣿⡿⠋⣿⣿⠀⠀⠀⠈⠙⢿⣿⣦
     ⠀⣾⣿⠋⠀⠀⣿⣿⠀⠀⣶⣿⠀⠀⠙⣿⣷
     ⣸⣿⠇⠀⠀⠀⣿⣿⠠⣾⡿⠃⠀⠀⠀⠸⣿⣇⠀⠀⣶⠀⣠⡶⠂⠀⣶⠀⠀⢰⡆⠀⢰⡆⢀⣴⠖⠀⢠⡶⠶⠶⡦⠀⠀⠀⣰⣶⡀
     ⣿⣿⠀⠀⠀⠀⠿⢿⣷⣦⡀⠀⠀⠀⠀⠀⣿⣿⠀⠀⣿⢾⣏⠀⠀⠀⣿⠀⠀⢸⡇⠀⢸⡷⣿⡁⠀⠀⠘⠷⠶⠶⣦⠀⠀⢠⡟⠘⣷
     ⢹⣿⡆⠀⠀⠀⣿⣶⠈⢻⣿⡆⠀⠀⠀⢰⣿⡏⠀⠀⠿⠀⠙⠷⠄⠀⠙⠷⠶⠟⠁⠀⠸⠇⠈⠻⠦⠀⠐⠷⠶⠶⠟⠀⠠⠿⠁⠀⠹⠧
     ⠀⢿⣿⣄⠀⠀⣿⣿⠀⠀⠿⣿⠀⠀⣠⣿⡿
     ⠀⠀⠻⣿⣷⡄⣿⣿⠀⠀⠀⢀⣠⣾⣿⠟    databroker-cli
     ⠀⠀⠀⠈⠛⠇⢿⣿⣿⣿⣿⡿⠿⠛⠁     v0.4.1
   
   Successfully connected to http://Server:55555/
   sdv.databroker.v1 >

   💡 Tip: The client retrieves metadata about the data entries that the Databroker knows about during startup. This allows for using TAB-completion of data entry names at the prompt.

2. Display help for supported commands

   help

   connect [URI]            Connect to server
   get <PATH> [[PATH] ...]  Get signal value(s)
   set <PATH> <VALUE>       Set actuator signal
   subscribe <QUERY>        Subscribe to signals with QUERY
   feed <PATH> <VALUE>      Publish signal value
   metadata [PATTERN]       Fetch metadata. Provide PATTERN to list metadata of signals matching pattern.
   token <TOKEN>            Use TOKEN as access token
   token-file <FILE>        Use content of FILE as access token
   help                     You're looking at it.
   quit                     Quit

3. Get the vehicle's current speed

   get Vehicle.Speed

   [get]  OK
   Vehicle.Speed: ( NotAvailable )

   📝 Note When Databroker starts up, all data entries are initialized to empty values. Thus, the vehicle speed is being reported as NotAvailable.

4. Set the vehicle's current speed

   publish Vehicle.Speed 100.34

   [set]  OK

5. Get the vehicle's current speed

   get Vehicle.Speed

   [get]  OK
   Vehicle.Speed: 100.34

Run the cli with:

4. Exit the client

   quit

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Usage

Please refer to the User Guide for details regarding how to run and interact with Kuksa Databroker.

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Building

Building Kuksa Databroker from source code requires

• a Rust tool chain
• a local workspace containing the source code

  git clone https://github.com/eclipse-kuksa/kuksa-databroker.git

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Building Examples and Binaries

# in ${WORKSPACE}
cargo build --examples --bins

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Building release Binaries

# in ${WORKSPACE}
cargo build --bins --release

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Runing Databroker Test Cases

# in ${WORKSPACE}
cargo test --all-targets

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Performance

The Kuksa team has released an official tool to measure the latency and throughput of the Databroker for all supported APIs: kuksa-perf

The use case measures the time it takes for a signal to be transferred from the Provider to the Signal Consumer Signal Consumer(stream subscribe) <- Databroker <- Provider(stream publish)

Feel free to use it and share your results with us!

Contributing

Please refer to the Kuksa Contributing Guide.

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License

Kuksa Databroker is provided under the terms of the Apache Software License 2.0.

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Contact

Please feel free to create GitHub Issues for reporting bugs and/or ask questions in our Gitter chat room.

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