This tutorial introduces the concept of an IoT Agent and wires up the dummy UltraLight 2.0 IoT devices created in the previous tutorial so that measurements can be read and commands can be sent using NGSI requests sent to the Orion Context Broker.

The docker-compose files for this tutorial can be found on GitHub:

GitHub

What is an IoT Agent?

"In every operation there is an above the line and a below the line. Above the line is what you do by the book. Below the line is how you do the job."

— John le Carré (A Perfect Spy)

An IoT Agent is a component that lets a group of devices send their data to and be managed from a Context Broker using their own native protocols. IoT Agents should also be able to deal with security aspects of the Fiware platform (authentication and authorization of the channel) and provide other common services to the device programmer.

The Orion Context Broker exclusively uses NGSI requests for all of its interactions. Each IoT Agent provides a North Port NGSI interface which is used for context broker interactions and all interactions beneath this port occur using the native protocol of the attached devices.

In effect, this brings a standard interface to all IoT interactions at the context information management level. Each group of IoT devices are able to use their own propriatory protocols and disparate transport mechanisms under the hood whilst the associated IoT Agent offers a facade pattern to handle this complexity.

IoT Agents already exist or are in development for many common transports and protocols. Examples include the following:

• IoTAgent-JSON (HTTP/MQTT transport) - a bridge between an HTTP/MQTT+JSON based protocol and NGSI
• IoTAgent-LWM2M (CoaP transport) - a bridge between the Lightweight M2M protocol and NGSI
• IoTAgent-UL (HTTP/MQTT transport) - a bridge between the UltraLight2.0 protocol and NGSI
• IoTagent-LoraWAN (CoaP transport) - a bridge between the LoraWAN protocol and NGSI

Southbound Traffic (Commands)

HTTP requests generated by the from the Context Broker and passed downwards towards an IoT device (via an IoT agent) are known as southbound traffic. Southbound traffic consists of commands made to actuator devices which alter the state of the real world by their actions.

For example to switch on a real-life UltraLight 2.0 Smart Lamp the following interactions would occur:

• An request is sent to the Context broker to invoke the on command of the Smart Lamp via NGSI
• The Context Broker finds the entity within the context and notes that the context provision for this attribute has been delegated to the IoT Agent
• The Context broker sends an NGSI request to the North Port of the IoT Agent to invoke the command
• The IoT Agent receives this Southbound request and converts it to UltraLight 2.0 syntax and passes it on to the Smart Lamp
• The Smart Lamp switches on the lamp and returns the result of the command to the IoT Agent in UltraLight 2.0 syntax
• The IoT Agent receives this Northbound request, interprets it and passes the result of the interaction into the context by making an NGSI request to the Context Broker.
• The Context Broker receives this Northbound request and updates the context with the result of the command.

• Requests between User and Context Broker use NGSI
• Requests between Context Broker and IoT Agent use NGSI
• Requests between IoT Agent and IoT Device use native protocols
• Requests between IoT Device and IoT Agent use native protocols
• Requests between IoT Agent and Context Broker use NGSI

Northbound Traffic (Measurements)

Requests generated from an IoT device and passed back upwards towards the Context Broker (via an IoT agent) are known as northbound traffic. Northbound traffic consists of measurements made by sensor devices and relays the state of the real world into the context data of the system.

For example for a real-life Motion Sensor to send a count measurement the following interactions would occur:

• A Motion Sensor makes a measurement and passes the result to the IoT Agent
• The IoT Agent receives this Northbound request, converts the result from UltraLight syntax and passes the result of the interaction into the context by making an NGSI request to the Context Broker.
• The Context Broker receives this Northbound request and updates the context with the result of the measurement.

• Requests between Iot-Device and IoT-Agent use native protocols
• Requests between Iot-Agent and Context-Broker use NGSI

Note Other more complex interactions are also possible, but this overview is sufficient to understand the basic principles of an IoT Agent.

Common Functionality

As can be seen from the previous sections, although each IoT Agent will be unique since they interpret different protocols, there will a large degree of similarity between IoT agents.

• Offering a standard location to listen to device updates
• Offering a standard location to listen to context data updates
• Holding a list of devices and mapping context data attributes to device syntax
• Security Authorization

This base functionality has been abstracted out into a common IoT Agent framework library

Device Monitor

For the purpose of this tutorial, a series of dummy IoT devices have been created, which will be attached to the context broker. The state of each device can be seen on the UltraLight device monitor web-page found at: http://localhost:3000/device/monitor

FIWARE Monitor

Architecture

This application builds on the components created in previous tutorials. It will make use of two FIWARE components - the Orion Context Broker and the IoT Agent for UltraLight 2.0. Usage of the Orion Context Broker is sufficient for an application to qualify as “Powered by FIWARE”. Both the Orion Context Broker and the IoT Agent rely on open source MongoDB technology to keep persistence of the information they hold. We will also be using the dummy IoT devices created in the previous tutorial

Therefore the overall architecture will consist of the following elements:

• The FIWARE Orion Context Broker which will receive requests using NGSI
• The FIWARE IoT Agent for UltraLight 2.0 which will receive southbound requests using NGSI and convert them to UltraLight 2.0 commands for the devices
• The underlying MongoDB database :
  • Used by the Orion Context Broker to hold context data information such as data entities, subscriptions and registrations
  • Used by the IoT Agent to hold device information such as device URLs and Keys
• The Context Provider NGSI proxy is not used in this tutorial. It does the following:
  • receive requests using NGSI
  • makes requests to publicly available data sources using their own APIs in a proprietory format
  • returns context data back to the Orion Context Broker in NGSI format.
• The Stock Management Frontend is not used in this tutorial will it does the following:
  • Display store information
  • Show which products can be bought at each store
  • Allow users to "buy" products and reduce the stock count.
• A webserver acting as set of [dummy IoT devices]](https://github.com/Fiware/tutorials.IoT-Sensors) using the UltraLight 2.0 protocol running over HTTP.

Since all interactions between the elements are initiated by HTTP requests, the entities can be containerized and run from exposed ports.

The necessary configuration information for wiring up the IoT devices and the IoT Agent can be seen in the services section of the associated docker-compose.yml file:

Dummy IoT Devices Configuration

context-provider:
    image: fiware/cp-web-app:latest
    hostname: context-provider
    container_name: context-provider
    networks:
        - default
    expose:
        - "3000"
        - "3001"
    ports:
        - "3000:3000"
        - "3001:3001"
    environment:
        - "DEBUG=proxy:*"
        - "PORT=3000"
        - "IOTA_HTTP_HOST=iot-agent"
        - "IOTA_HTTP_PORT=7896"
        - "DUMMY_DEVICES_PORT=3001"
        - "DUMMY_DEVICES_API_KEY=4jggokgpepnvsb2uv4s40d59ov"

The context-provider container is listening on two ports:

• Port 3000 is exposed so we can see the web-page displaying the Dummy IoT devices.
• Port 3001 is exposed purely for tutorial access - so that cUrl or Postman can make UltraLight commands without being part of the same network.

The context-provider container is driven by environment variables as shown:

The other context-provider container configuration values described in the YAML file are not used in this tutorial.

IoT Agent for UltraLight 2.0 Configuration

The IoT Agent for UltraLight 2.0 can be instantiated within a Docker container. An offical Docker image is available from Docker Hub tagged fiware/iotagent-ul. The necessary configuration can be seen below:

iot-agent:
    image: fiware/iotagent-ul:latest
    hostname: iot-agent
    container_name: iot-agent
    depends_on:
      - context-db
      - orion
    networks:
        - default
    expose:
        - "4041"
        - "7896"
    ports:
        - "4041:4041"
        - "7896:7896"
    environment:
        - "IOTA_CB_HOST=orion"
        - "IOTA_CB_PORT=1026"
        - "IOTA_NORTH_PORT=4041"
        - "IOTA_REGISTRY_TYPE=mongodb"
        - "IOTA_LOG_LEVEL=DEBUG"
        - "IOTA_TIMESTAMP=true"
        - "IOTA_MONGO_HOST=context-db"
        - "IOTA_MONGO_PORT=27017"
        - "IOTA_MONGO_DB=iotagentul"
        - "IOTA_HTTP_PORT=7896"
        - "IOTA_PROVIDER_URL=http://iot-agent:4041"

The iot-agent container relies on the precence of the Orion Context Broker and uses a MongoDB database to hold device information such as device URLs and Keys. The container is listening on two ports:

• Port 7896 is exposed to receive Ultralight measurements over HTTP from the Dummy IoT devices
• Port 4041 is exposed purely for tutorial access - so that cUrl or Postman can make provisioning commands without being part of the same network.

The iot-agent container is driven by environment variables as shown: