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Bifravst

Gvðín gerþu bru af iorþu til himins, er heitir Bifravst. Bifravst is a term from the Nordic mythology and it refers to the bridge built by the gods between earth and heaven. Read more about it.

Vision

Bifravst aims to provide a concrete end-to-end example for an ultra-low power cellular IoT product in the asset tracker space, namely a Cat Tracker.

Bifravst enables the developers to set up a real world IoT solution using the respective cloud provider and adapt the example firmware and software quickly for a specific use case. Bifravst aims to provide answers and recommend best practices to the following questions:

• How can you connect Nordic’s cellular IoT chips to your cloud provider?

• How do devices send data into the cloud?*

• How can the data be sent to the devices?

• How can users and other services interact with the devices?

• How can you upgrade the application firmware of your devices while they are deployed in the field?

• How can you develop a cellular IoT product that maximizes battery life, minimizes data usage, and handles unreliable connectivity gracefully?

Note

In the coming weeks, we will establish the best path to provide this project through nRF Connect SDK, Nordic Semiconductor Infocenter and other established channels. For more information, see the GitHub issue.

Core principles

Bifravst is built on the following principles:

• Teach by showing

  • All examples are designed to solve a concrete use case (a Cat Tracker) instead of providing generic or abstract solutions.

  • Bifravst is not a framework, but it is a real application.

• Err on the side of security

  • Bifravst follows the most robust security recommendations of the respective cloud provider.

• Single tenancy

  • Bifravst implements a scenario in which all the authenticated users can be trusted to access all the devices.

  • It is a typical scenario for cellular IoT products, and it simplifies the onboarding of new devices.

• Serverless

  • Bifravst uses a serverless architecture as much as possible to have near-zero costs for the operation during the development, and to provide horizontal scaling of resources to be used in a production system if needed.

• Cloud native

  • Bifravst examples are designed by following the best practices of the respective cloud provider to reduce development efforts due to abstraction.

• Being offline is not an exception

  • Highly mobile cellular IoT products need to handle unreliable connections gracefully, by implementing mechanisms to retry the failed sending of data. This also means that the sensor measurements need to be timestamped when they are created, and not when they arrive at the cloud.

• Maximize power saving

  • The firmware examples should highlight power saving features of the nRF9160 DK because this is critical for developing very small form-factor devices.

Note

Bifravst is not a multi-cloud solution. The concrete implementation will differ for each cloud provider.

Bifravst does not aim to provide a solution where you can switch in a seamingless manner between cloud providers. Such a solution will require the implementation of additional abstraction layers, which instead of becoming a meaningful benefit for the majority of users, mandate a constant translation between the vendor specific concepts and the abstraction. Instead, in Bifravst, the best practices of the respective cloud-vendor for building a serverless IoT solution are followed.

Project overview

Bifravst is licensed under the 3-clause BSD license (software) and the Nordic 5-clause BSD license (firmware). Below table shows the characteristics of Bifravst project:

Characteristic	Principle
Development model	Open
License	Open source
Cloud vendor support	Multiple
Feature set	Specialized, small
Hosting	Self-hosted
User Interface	Mobile-first web-app
Cloud Tenancy	Single
Integration of Cloud resources	Native
Device paradigm	Offline mostly
Sensor timestamping	Device-side

Note

Development progress is managed in the Bifravst GitHub Project.

System overview and technical considerations

Devices connect to the message broker using TLS over TCP. The messaging protocol is JSON over MQTT. The TLS certificates are generated offline by the developer to simplify the provisioning during production.

See below for an overview of system components:

System overview

The cloud and the web application are developed using TypeScript (a typed superset of JavaScript). JavaScript is the most popular language according to the 2019 Stack Overflow survey. Most of the cloud providers provide their SDKs in JavaScript.

It provides tools to configure the developer’s cloud account for use with the developer’s devices and the single-page application (SPA). After the cloud account has been configured, it provides the resources necessary for the asset trackers to connect to the message broker and to send and receive messages. It also provides the appropriate APIs for the SPA to interact with the developer’s devices.

The mobile-first SPA is developed using create-react-app and it provides a reference implementation of a user interface to control and interact with the devices.

The web application offers the following features:

• User registration including password recovery

  • Optional feature

  • Requires user approval by an admin

• Listing of asset trackers

• Viewing of asset trackers

  • Current and historical device data

    • GPS location

    • Battery voltage

    • Accelerometer

  • Configure asset tracker

    • Update interval

    • Sensor threshold

• Managing of asset trackers

  • Delete asset tracker

  • Firmware upgrade

Supported cloud providers

See the below table for a list of supported cloud providers:

	Amazon Web Services	Google Cloud	Microsoft Azure	Alibaba Cloud
LTE-M: TCP+MQTT	feature complete	on hold	in progress	Planned
NB-IoT: UDP+LWM2M	Planned	Planned	Planned	Planned

For cloud providers having no native UDP+LWM2M support, using a bridge such as Eclipse Californium, was evaluated. For more information see Leshan LwM2M AWS IoT Gateway.

IoT Cloud vendor survey results

Below table shows the IoT Cloud vendor survey results:

	Nordic internal (2019)	Eclipse Foundation (2019)
AWS	1. 100%	1.100%
Google	2. 79%	3. 73%
Azure	3. 66%	2. 84%
ARM Pelion	4. 25%
IBM	5. 20%

Documentation

• Bifravst on AWS
  • Getting started
  • Upgrading an existing installation
  • Device credentials
  • Connect using the simulator
  • Continuous deployment
  • Authentication
  • AWS IoT Shadow and Topics
  • Limiting the Shadow Document size
  • Storage of historical data
  • Continuous integration
  • Unwired Labs API
  • Uninstalling Bifravst from AWS
  • SNI
• Bifravst on Azure
  • Getting started
  • Running the application locally with Docker
  • Upgrading an existing installation
  • Device credentials
  • Connect using the simulator
  • Continuous deployment
  • Continuous integration
  • Unwired Labs’ LocationAPI
  • Azure IoT Shadow and Topics
  • Using Azure AD B2C to secure your Azure Functions Apps
• Cat Tracker Web Application
  • Getting started
  • Upgrading an existing installation
  • Deploying Cat Tracker to AWS
  • Deploying Cat Tracker to Azure
  • Cell geolocation
  • Customizing the Cat Tracker web application
• Cat Tracker firmware
  • Functional Overview
  • Using pre-build images
  • Configuration
  • Building using Docker
  • Building using your local system
  • Building using GitHub actions
  • Continuous Integration of Firmware
  • Device-Cloud-Protocol
  • Device Data and Configuration
  • LED schema
• Connect using a real device
  • Provisioning the certificate
  • Troubleshooting
  • Firmware over-the-air (FOTA)

Guides

• Automate building of HEX files for your nRF Connect SDK application
• Cell Geolocations
• Cloud connectivity and protocols for the Internet of Things
• Cloud Differences
• Cyber Security for Consumer Internet of Things: Baseline Requirements
• Versioning

Resources

• GitHub
• DevZone
• Support
• Architecture Decision Records
  • 2. Use NPM registry
  • 3. Use saga as the name for the main branch
• Code of Conduct

Acknowledgments

Pin Icon created by Nun from the Noun Project. Cat Icon created by Focus Lab from the Noun Project. Amazon Web Services, the AWS logo are trademarks of Amazon.com, Inc. or its affiliates in the United States and/or other countries. Google and the Google logo are registered trademarks of Google LLC. Microsoft and Azure are registered trademarks of Microsoft Corporation in the United States and/or other countries.