What is an IoT Agent?

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-v2 requests sent to the Orion Context Broker.

The tutorial uses cUrl commands throughout, but is also available as Postman documentation

このチュートリアルは日本語でもご覧いただけます。

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-v2 requests for all of its interactions. Each IoT Agent provides a North Port NGSI-v2 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 proprietary 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 IoT communication protocols and data models. Examples include the following:

IoTAgent-JSON - a bridge between HTTP/MQTT messaging (with a JSON payload) and NGSI
IoTAgent-LWM2M - a bridge between the Lightweight M2M protocol and NGSI
IoTAgent-UL - a bridge between HTTP/MQTT messaging (with an UltraLight2.0 payload) and NGSI
IoTagent-LoRaWAN - a bridge between the LoRaWAN protocol and NGSI
IoTagent-OPCUA - a bridge between the OPC-UA protocol and NGSI

Southbound Traffic (Commands)

HTTP requests generated by the Orion 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 NGSI PATCH request is sent to the Context broker to update the current context of Smart Lamp

this is effectively an indirect request invoke the on command of the Smart Lamp

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. Details of the architecture and protocol used can be found in the IoT Sensors tutorial The state of each device can be seen on the UltraLight device monitor web page found at: http://localhost:3000/device/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-v2
The FIWARE IoT Agent for UltraLight 2.0 which will receive southbound requests using NGSI-v2 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-v2
- makes requests to publicly available data sources using their own APIs in a proprietary format
- returns context data back to the Orion Context Broker in NGSI-v2 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 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

tutorial:
    image: quay.io/fiware/tutorials.context-provider
    hostname: iot-sensors
    container_name: fiware-tutorial
    networks:
        - default
    expose:
        - '3000'
        - '3001'
    ports:
        - '3000:3000'
        - '3001:3001'
    environment:
        - 'DEBUG=tutorial:*'
        - 'PORT=3000'
        - 'IOTA_HTTP_HOST=iot-agent'
        - 'IOTA_HTTP_PORT=7896'
        - 'DUMMY_DEVICES_PORT=3001'
        - 'DUMMY_DEVICES_API_KEY=4jggokgpepnvsb2uv4s40d59ov'
        - 'DUMMY_DEVICES_TRANSPORT=HTTP'

The tutorial 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 tutorial container is driven by environment variables as shown:

Key	Value	Description
DEBUG	`tutorial:*`	Debug flag used for logging
WEB_APP_PORT	`3000`	Port used by web-app which displays the dummy device data
IOTA_HTTP_HOST	`iot-agent`	The hostname of the IoT Agent for UltraLight 2.0 - see below
IOTA_HTTP_PORT	`7896`	The port that the IoT Agent for UltraLight 2.0 will be listening on. `7896` is a common default for UltraLight over HTTP
DUMMY_DEVICES_PORT	`3001`	Port used by the dummy IoT devices to receive commands
DUMMY_DEVICES_API_KEY	`4jggokgpepnvsb2uv4s40d59ov`	Random security key used for UltraLight interactions - used to ensure the integrity of interactions between the devices and the IoT Agent
DUMMY_DEVICES_TRANSPORT	`HTTP`	The transport protocol used by the dummy IoT devices

The other tutorial 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 official Docker image is available from Docker Hub tagged fiware/iotagent-ul. The necessary configuration can be seen below:

iot-agent:
    image: quay.io/fiware/iotagent-ul:latest
    hostname: iot-agent
    container_name: fiware-iot-agent
    depends_on:
        - mongo-db
    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_CB_NGSI_VERSION=v2
        - IOTA_AUTOCAST=true
        - IOTA_MONGO_HOST=mongo-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:

Key	Value	Description
IOTA_CB_HOST	`orion`	Hostname of the context broker to update context
IOTA_CB_PORT	`1026`	Port that context broker listens on to update context
IOTA_NORTH_PORT	`4041`	Port used for Configuring the IoT Agent and receiving context updates from the context broker
IOTA_REGISTRY_TYPE	`mongodb`	Whether to hold IoT device info in memory or in a database
IOTA_LOG_LEVEL	`DEBUG`	The log level of the IoT Agent
IOTA_TIMESTAMP	`true`	Whether to supply timestamp information with each measurement received from attached devices
IOTA_CB_NGSI_VERSION	`v2`	Whether to supply use NGSI v2 when sending updates for active attributes
IOTA_AUTOCAST	`true`	Ensure Ultralight number values are read as numbers not strings
IOTA_MONGO_HOST	`context-db`	The hostname of mongoDB - used for holding device information
IOTA_MONGO_PORT	`27017`	The port mongoDB is listening on
IOTA_MONGO_DB	`iotagentul`	The name of the database used in mongoDB
IOTA_HTTP_PORT	`7896`	The port where the IoT Agent listens for IoT device traffic over HTTP
IOTA_PROVIDER_URL	`http://iot-agent:4041`	URL passed to the Context Broker when commands are registered, used as a forwarding URL location when the Context Broker issues a command to a device

Prerequisites

Docker

To keep things simple all components will be run using Docker. Docker is a container technology which allows to different components isolated into their respective environments.

To install Docker on Windows follow the instructions here
To install Docker on Mac follow the instructions here
To install Docker on Linux follow the instructions here

Docker Compose is a tool for defining and running multi-container Docker applications. A YAML file is used configure the required services for the application. This means all container services can be brought up in a single command. Docker Compose is installed by default as part of Docker for Windows and Docker for Mac, however Linux users will need to follow the instructions found here

You can check your current Docker and Docker Compose versions using the following commands:

docker-compose -v
docker version

Please ensure that you are using Docker version 20.10 or higher and Docker Compose 1.29 or higher and upgrade if necessary.

Cygwin

We will start up our services using a simple bash script. Windows users should download cygwin to provide a command-line functionality similar to a Linux distribution on Windows.

Start Up

Before you start you should ensure that you have obtained or built the necessary Docker images locally. Please clone the repository and create the necessary images by running the commands as shown:

git clone https://github.com/FIWARE/tutorials.IoT-Agent.git
cd tutorials.IoT-Agent
git checkout NGSI-v2

./services create

Thereafter, all services can be initialized from the command-line by running the services Bash script provided within the repository:

./services start

Note

If you want to clean up and start over again you can do so with the following command:

./services stop

Provisioning an IoT Agent

To follow the tutorial correctly please ensure you have the device monitor page available in your browser and click on the page to enable audio before you enter any cUrl commands. The device monitor displays the current state of an array of dummy devices using Ultralight 2.0 syntax

Device Monitor

The device monitor can be found at: http://localhost:3000/device/monitor

Checking the IoT Agent Service Health

You can check if the IoT Agent is running by making an HTTP request to the exposed port:

1️⃣ Request:

curl -X GET \
  'http://localhost:4041/iot/about'

The response will look similar to the following:

{
    "libVersion": "3.4.0",
    "port": "4041",
    "baseRoot": "/",
    "version": "2.4.0"
}

What if I get a Failed to connect to localhost port 4041: Connection refused Response?

If you get a Connection refused response, the IoT Agent cannot be found where expected for this tutorial - you will need to substitute the URL and port in each cUrl command with the corrected IP address. All the cUrl commands tutorial assume that the IoT Agent is available on localhost:4041.

Try the following remedies:

To check that the docker containers are running try the following:
docker ps
You should see four containers running. If the IoT Agent is not running, you can restart the containers as necessary. This command will also display open port information.

If you have installed docker-machine and Virtual Box, the context broker, IoT Agent and Dummy Device docker containers may be running from another IP address - you will need to retrieve the virtual host IP as shown:
curl -X GET \
 'http://$(docker-machine ip default):4041/version'
Alternatively run all your curl commands from within the container network:
docker run --network fiware_default --rm appropriate/curl -s \
 -X GET 'http://iot-agent:4041/iot/about'

Connecting IoT Devices

The IoT Agent acts as a middleware between the IoT devices and the context broker. It therefore needs to be able to create context data entities with unique IDs. Once a service has been provisioned and an unknown device makes a measurement the IoT Agent add this to the context using the supplied <device-id> (unless the device is recognized and can be mapped to a known ID.

There is no guarantee that every supplied IoT device <device-id> will always be unique, therefore all provisioning requests to the IoT Agent require two mandatory headers:

fiware-service header is defined so that entities for a given service can be held in a separate mongoDB database.
fiware-servicepath can be used to differentiate between arrays of devices.

For example within a smart city application you would expect different fiware-service headers for different departments (e.g. parks, transport, refuse collection etc.) and each fiware-servicepath would refer to specific park and so on. This would mean that data and devices for each service can be identified and separated as needed, but the data would not be siloed - for example data from a Smart Bin within a park can be combined with the GPS Unit of a refuse truck to alter the route of the truck in an efficient manner.

The Smart Bin and GPS Unit are likely to come from different manufacturers and it cannot be guaranteed that there is no overlap within <device-id>s used. The use of the fiware-service and fiware-servicepath headers can ensure that this is always the case, and allows the context broker to identify the original source of the context data.

Provisioning a Service Group

Invoking group provision is always the first step in connecting devices since it is always necessary to supply an authentication key with each measurement and the IoT Agent will not initially know which URL the context broker is responding on.

It is also possible to set up default commands and attributes for all anonymous devices as well, but this is not done within this tutorial as we will be provisioning each device separately.

This example provisions an anonymous group of devices. It tells the IoT Agent that a series of devices will be sending messages to the IOTA_HTTP_PORT (where the IoT Agent is listening for Northbound communications)

2️⃣ Request:

curl -iX POST \
  'http://localhost:4041/iot/services' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
 "services": [
   {
     "apikey":      "4jggokgpepnvsb2uv4s40d59ov",
     "cbroker":     "http://orion:1026",
     "entity_type": "Thing",
     "resource":    "/iot/d"
   }
 ]
}'

In the example the IoT Agent is informed that the /iot/d endpoint will be used and that devices will authenticate themselves by including the token 4jggokgpepnvsb2uv4s40d59ov. For an UltraLight IoT Agent this means devices will be sending GET or POST requests to:

http://iot-agent:7896/iot/d?i=<device_id>&k=4jggokgpepnvsb2uv4s40d59ov

Which should be familiar UltraLight 2.0 syntax from the previous tutorial.

When a measurement from an IoT device is received on the resource URL it needs to be interpreted and passed to the context broker. The entity_type attribute provides a default type for each device which has made a request (in this case anonymous devices will be known as Thing entities. Furthermore the location of the context broker (cbroker) is needed, so that the IoT Agent can pass on any measurements received to the correct location. cbroker is an optional attribute - if it is not provided, the IoT Agent uses the context broker URL as defined in the configuration file, however it has been included here for completeness.

Provisioning a Sensor

It is common good practice to use URNs following the NGSI-LD specification when creating entities. Furthermore it is easier to understand meaningful names when defining data attributes. These mappings can be defined by provisioning a device individually.

Three types of measurement attributes can be provisioned:

attributes are active readings from the device
lazy attributes are only sent on request - The IoT Agent will inform the device to return the measurement
static_attributes are as the name suggests static data about the device (such as relationships) passed on to the context broker.

Note

In the case where individual ids are not required, or aggregated data is sufficient the attributes can be defined within the provisioning service rather than individually.

3️⃣ Request:

curl -iX POST \
  'http://localhost:4041/iot/devices' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
 "devices": [
   {
     "device_id":   "motion001",
     "entity_name": "urn:ngsi-ld:Motion:001",
     "entity_type": "Motion",
     "timezone":    "Europe/Berlin",
     "attributes": [
       { "object_id": "c", "name": "count", "type": "Integer" }
     ],
     "static_attributes": [
       { "name":"refStore", "type": "Relationship", "value": "urn:ngsi-ld:Store:001"}
     ]
   }
 ]
}
'

In the request we are associating the device motion001 with the URN urn:ngsi-ld:Motion:001 and mapping the device reading c with the context attribute count (which is defined as an Integer) A refStore is defined as a static_attribute, placing the device within Store urn:ngsi-ld:Store:001.

Static attributes are useful as additional data on an entity to enable querying using the q parameter. For example the Smart Data Models Device model defines attributes such as category or controlledProperty which enable queries to be made like:

Which Actuators currently have a low batteryLevel?

/v2/entities?q=category=="actuator";batteryLevel<0.1

Which Devices measuring fillingLevel were installed before January 2020?

/v2/entities?q=controlledProperty=="fillingLevel";dateInstalled<"2020-01-25T00:00:00.000Z"

Obviously static data can be extended as necessary and can also include additional data such as a unique name or serialNumber for each device should the entity ID be too inflexible for queries.

/v2/entities?q=serialNumber=="XS403001-002"

Additionally devices with a fixed location static attribute can also be queried using the Geofencing parameters.

/v2/entities?georel=near;maxDistance:1500&geometry=point&coords=52.5162,13.3777

You can simulate a dummy IoT device measurement coming from the Motion Sensor device motion001, by making the following request

4️⃣ Request:

curl -iX POST \
  'http://localhost:7896/iot/d?k=4jggokgpepnvsb2uv4s40d59ov&i=motion001' \
  -H 'Content-Type: text/plain' \
  -d 'c|1'

A similar request was made in the previous tutorial (before the IoT Agent was connected) when the door was unlocked, you will have seen the state of each motion sensor changing and a Northbound request will be logged in the device monitor.

Now the IoT Agent is connected, the service group has defined the resource upon which the IoT Agent is listening (iot/d) and the API key used to authenticate the request (4jggokgpepnvsb2uv4s40d59ov). Since both of these are recognized, the measurement is valid.

Because we have specifically provisioned the device (motion001) - the IoT Agent is able to map attributes before raising a request with the Orion Context Broker.

You can see that a measurement has been recorded, by retrieving the entity data from the context broker. Don't forget to add the fiware-service and fiware-service-path headers.

5️⃣ Request:

curl -X GET \
  'http://localhost:1026/v2/entities/urn:ngsi-ld:Motion:001?type=Motion' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Response:

{
    "id": "urn:ngsi-ld:Motion:001",
    "type": "Motion",
    "TimeInstant": {
        "type": "ISO8601",
        "value": "2018-05-25T10:51:32.00Z",
        "metadata": {}
    },
    "count": {
        "type": "Integer",
        "value": "1",
        "metadata": {
            "TimeInstant": {
                "type": "ISO8601",
                "value": "2018-05-25T10:51:32.646Z"
            }
        }
    },
    "refStore": {
        "type": "Relationship",
        "value": "urn:ngsi-ld:Store:001",
        "metadata": {
            "TimeInstant": {
                "type": "ISO8601",
                "value": "2018-05-25T10:51:32.646Z"
            }
        }
    }
}

The response shows that the Motion Sensor device with id=motion001 has been successfully identified by the IoT Agent and mapped to the entity id=urn:ngsi-ld:Motion:001. This new entity has been created within the context data. The c attribute from the dummy device measurement request has been mapped to the more meaningful count attribute within the context. As you will notice, a TimeInstant attribute has been added to both the entity and the metadata of the attribute - this represents the last time the entity and attribute have been updated, and is automatically added to each new entity because the IOTA_TIMESTAMP environment variable was set when the IoT Agent was started up. The refStore attribute comes from the static_attributes set when the device was provisioned.

Provisioning an Actuator via a Command

Provisioning an actuator is similar to provisioning a sensor. This time an endpoint attribute holds the location where the IoT Agent needs to send the UltraLight command and the commands array includes a list of each command that can be invoked. The example below provisions a bell with the deviceId=bell001. The endpoint is http://iot-sensors:3001/iot/bell001 and it can accept the ring command. The transport=HTTP attribute defines the communications protocol to be used.

6️⃣ Request:

curl -iX POST \
  'http://localhost:4041/iot/devices' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "devices": [
    {
      "device_id": "bell001",
      "entity_name": "urn:ngsi-ld:Bell:001",
      "entity_type": "Bell",
      "protocol": "PDI-IoTA-UltraLight",
      "transport": "HTTP",
      "endpoint": "http://iot-sensors:3001/iot/bell001",
      "commands": [
        { "name": "ring", "type": "command" }
       ],
       "static_attributes": [
         {"name":"refStore", "type": "Relationship","value": "urn:ngsi-ld:Store:001"}
      ]
    }
  ]
}
'

Provisioning an Actuator via a Bidirectional attribute

An actuator can also be provisioned using a bidirectional attribute. Once again an endpoint attribute holds the location where the IoT Agent needs to send the UltraLight command. The ring attribute is defined using an expression and mapped to itself in the reverse direction. When an update to the ring attribute is received, it is also sent to the device itself. Internally the difference is that this method relies on a subscription rather than a registration.

Note: This functionality has been removed in version 2.4.0 and higher.

7️⃣ Request:

curl -L -X POST 'http://localhost:4041/iot/devices' \
-H 'fiware-service: openiot' \
-H 'fiware-servicepath: /' \
-H 'Content-Type: application/json' \
--data-raw '{
  "devices": [
    {
      "device_id": "bell002",
      "entity_name": "urn:ngsi-ld:Bell:002",
      "entity_type": "Bell",
      "protocol": "PDI-IoTA-UltraLight",
      "transport": "HTTP",
      "endpoint": "http://iot-sensors:3001/iot/bell002",
      "attributes": [
            {
                "name": "ring",
                "type": "Text",
                "expression": "ring",
                "reverse": [
                    {
                        "object_id": "ring",
                        "type": "Text",
                        "expression": "ring | toString()"
                    }
                ]
            }
       ],
       "static_attributes": [
         {"name":"refStore", "type": "Relationship","value": "urn:ngsi-ld:Store:002"}
        ]
    }
  ]
}
'

Before we wire-up the context broker, we can test that a command can be send to a device by making a REST request directly to the IoT Agent's North Port using the /v2/op/update endpoint. It is this endpoint that will eventually be invoked by the context broker once we have connected it up.

To test the configuration you can run the command directly as shown:

8️⃣ Request:

curl -iX POST \
  http://localhost:4041/v2/op/update \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
    "actionType": "update",
    "entities": [
        {
            "type": "Bell",
            "id": "urn:ngsi-ld:Bell:001",
            "ring" : {
                "type": "command",
                "value": ""
            }
        }
    ]
}'

If you are viewing the device monitor page, you can also see the state of the bell change.

The result of the command to ring the bell can be read by querying the entity within the Orion Context Broker.

9️⃣ Request:

curl -X GET \
  'http://localhost:1026/v2/entities/urn:ngsi-ld:Bell:001?type=Bell&options=keyValues' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Response:

{
    "id": "urn:ngsi-ld:Bell:001",
    "type": "Bell",
    "TimeInstant": "2018-05-25T20:06:28.00Z",
    "refStore": "urn:ngsi-ld:Store:001",
    "ring_info": " ring OK",
    "ring_status": "OK",
    "ring": ""
}

The TimeInstant shows last the time any command associated with the entity has been invoked. The result of ring command can be seen in the value of the ring_info attribute.

Provisioning a Smart Door

Provisioning a device which offers both commands and measurements is merely a matter of making an HTTP POST request with both attributes and command attributes in the body of the request.

1️⃣0️⃣ Request:

curl -iX POST \
  'http://localhost:4041/iot/devices' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "devices": [
    {
      "device_id": "door001",
      "entity_name": "urn:ngsi-ld:Door:001",
      "entity_type": "Door",
      "protocol": "PDI-IoTA-UltraLight",
      "transport": "HTTP",
      "endpoint": "http://iot-sensors:3001/iot/door001",
      "commands": [
        {"name": "unlock","type": "command"},
        {"name": "open","type": "command"},
        {"name": "close","type": "command"},
        {"name": "lock","type": "command"}
       ],
       "attributes": [
        {"object_id": "s", "name": "state", "type":"Text"}
       ],
       "static_attributes": [
         {"name":"refStore", "type": "Relationship","value": "urn:ngsi-ld:Store:001"}
       ]
    }
  ]
}
'

Provisioning a Smart Lamp

Similarly, a Smart Lamp with two commands (on and off) and two attributes can be provisioned as follows:

1️⃣1️⃣ Request:

curl -iX POST \
  'http://localhost:4041/iot/devices' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "devices": [
    {
      "device_id": "lamp001",
      "entity_name": "urn:ngsi-ld:Lamp:001",
      "entity_type": "Lamp",
      "protocol": "PDI-IoTA-UltraLight",
      "transport": "HTTP",
      "endpoint": "http://iot-sensors:3001/iot/lamp001",
      "commands": [
        {"name": "on","type": "command"},
        {"name": "off","type": "command"}
       ],
       "attributes": [
        {"object_id": "s", "name": "state", "type":"Text"},
        {"object_id": "l", "name": "luminosity", "type":"Integer"}
       ],
       "static_attributes": [
         {"name":"refStore", "type": "Relationship","value": "urn:ngsi-ld:Store:001"}
      ]
    }
  ]
}
'

The full list of provisioned devices can be obtained by making a GET request to the /iot/devices endpoint.

1️⃣2️⃣ Request:

curl -X GET \
  'http://localhost:4041/iot/devices' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Enabling Context Broker Commands

Having connected up the IoT Agent to the IoT devices, the Orion Context Broker was informed that the commands now are available. In other words the IoT Agent registered itself as a Context Provider for the command attributes.

Once the commands have been registered it will be possible to ring the Bell, open and close the Smart Door and switch the Smart Lamp on and off by sending requests to the Orion Context Broker, rather than sending UltraLight 2.0 requests directly the IoT devices as we did in the previous tutorial

Note

If the device is provisioned, but no data concerning the Entity is present in the context yet, the invocation must include the type of the Entity to succeed. However if the Entity type is already known to the broker, this hint is not necessary. This is because the registration is matched on both id and type.

Ringing the Bell

To invoke the ring command, the ring attribute must be updated in the context.

1️⃣3️⃣ Request:

curl -iX PATCH \
  'http://localhost:1026/v2/entities/urn:ngsi-ld:Bell:001/attrs?type=Bell' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "ring": {
      "type" : "command",
      "value" : ""
  }
}'

If you are viewing the device monitor page, you can also see the state of the bell change.

Opening the Smart Door

To invoke the open command, the open attribute must be updated in the context.

1️⃣4️⃣ Request:

curl -iX PATCH \
  'http://localhost:1026/v2/entities/urn:ngsi-ld:Door:001/attrs?type=Door' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "open": {
      "type" : "command",
      "value" : ""
  }
}'

Switching on the Smart Lamp

To switch on the Smart Lamp, the on attribute must be updated in the context.

1️⃣5️⃣ Request:

curl -iX PATCH \
  'http://localhost:1026/v2/entities/urn:ngsi-ld:Lamp:001/attrs?type=Lamp' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "on": {
      "type" : "command",
      "value" : ""
  }
}'

Service Group CRUD Actions

The CRUD operations for provisioning a service group map on to the expected HTTP verbs under the /iot/services endpoint

Create - HTTP POST
Read - HTTP GET
Update - HTTP PUT
Delete - HTTP DELETE

Use the resource and apikey parameters to uniquely identify a service group.

Creating a Service Group

This example provisions an anonymous group of devices. It tells the IoT Agent that a series of devices will be sending messages to the IOTA_HTTP_PORT (where the IoT Agent is listening for Northbound communications)

1️⃣6️⃣ Request:

curl -iX POST \
  'http://localhost:4041/iot/services' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
 "services": [
   {
     "apikey":      "12345",
     "cbroker":     "http://orion:1026",
     "entity_type": "Thing",
     "resource":    "/iot/d"
   }
 ]
}'

Read Service Group Details

This example obtains the full details of a provisioned service with a given resource path.

Service group details can be read by making a GET request to the /iot/services endpoint and providing a resource parameter.

1️⃣7️⃣ Request:

curl -X GET \
  'http://localhost:4041/iot/services?resource=/iot/d' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Response:

{
    "_id": "5b07b2c3d7eec57836ecfed4",
    "subservice": "/",
    "service": "openiot",
    "apikey": "4jggokgpepnvsb2uv4s40d59ov",
    "resource": "/iot/d",
    "attributes": [],
    "lazy": [],
    "commands": [],
    "entity_type": "Thing",
    "internal_attributes": [],
    "static_attributes": []
}

The response includes all the defaults associated with each service group such as the entity_type and any default commands or attribute mappings.

List all Service Groups

This example lists all provisioned services by making a GET request to the /iot/services endpoint.

1️⃣8️⃣ Request:

curl -X GET \
  'http://localhost:4041/iot/services' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Response:

{
    "_id": "5b07b2c3d7eec57836ecfed4",
    "subservice": "/",
    "service": "openiot",
    "apikey": "4jggokgpepnvsb2uv4s40d59ov",
    "resource": "/iot/d",
    "attributes": [],
    "lazy": [],
    "commands": [],
    "entity_type": "Thing",
    "internal_attributes": [],
    "static_attributes": []
}

The response includes all the defaults associated with each service group such as the entity_type and any default commands or attribute mappings.

Update a Service Group

This example updates an existing service group with a given resource path and apikey

Service group details can be updated by making a PUT request to the /iot/services endpoint and providing a resource and apikey parameters.

1️⃣9️⃣ Request:

curl -iX PUT \
  'http://localhost:4041/iot/services?resource=/iot/d&apikey=4jggokgpepnvsb2uv4s40d59ov' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "entity_type": "IoT-Device"
}'

Delete a Service Group

This example removes a provisioned service group by making a DELETE request to the /iot/services/ endpoint.

It means that requests to http://iot-agent:7896/iot/d?i=<device_id>&k=4jggokgpepnvsb2uv4s40d59ov (where the IoT Agent is listening for Northbound communications) should no longer be processed by the IoT Agent. The apiKey and resource parameters must be supplied in order to identify the service group to be deleted.

2️⃣0️⃣ Request:

curl -iX DELETE \
  'http://localhost:4041/iot/services/?resource=/iot/d&apikey=4jggokgpepnvsb2uv4s40d59ov' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Device CRUD Actions

The CRUD operations for provisioning individual devices map on to the expected HTTP verbs under the /iot/devices endpoint

Create - HTTP POST
Read - HTTP GET
Update - HTTP PUT
Delete - HTTP DELETE

Use the <device-id> to uniquely identify a device.

Creating a Provisioned Device

This example provisions an individual device. It maps the device_id=bell002 to the entity URN urn:ngsi-ld:Bell:002 and gives the entity a type Bell. The IoT Agent has been informed that the device offers a single ring command and is listening on http://iot-sensors:3001/iot/bell002 using HTTP. attributes, lazy attributes and static_attributes can also be provisioned.

2️⃣1️⃣ Request:

curl -iX POST \
  'http://localhost:4041/iot/devices' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "devices": [
    {
      "device_id": "bell002",
      "entity_name": "urn:ngsi-ld:Bell:002",
      "entity_type": "Bell",
      "protocol": "PDI-IoTA-UltraLight",
      "transport": "HTTP",
      "endpoint": "http://iot-sensors:3001/iot/bell002",
      "commands": [
        {
          "name": "ring",
          "type": "command"
        }
       ],
       "static_attributes": [
         {"name":"refStore", "type": "Relationship","value": "urn:ngsi-ld:Store:002"}
      ]
    }
  ]
}'

Read Provisioned Device Details

This example obtains the full details of a provisioned device with a given <device-id> path.

Provisioned Device details can be read by making a GET request to the /iot/devices/<device-id> endpoint.

2️⃣2️⃣ Request:

curl -X GET \
  'http://localhost:4041/iot/devices/bell002' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Response:

The response includes all the commands and attributes mappings associated with the device.

{
    "device_id": "bell002",
    "service": "openiot",
    "service_path": "/",
    "entity_name": "urn:ngsi",
    "entity_type": "Bell",
    "endpoint": "http://iot-sensors:3001/iot/bell002",
    "transport": "HTTP",
    "attributes": [],
    "lazy": [],
    "commands": [
        {
            "object_id": "ring",
            "name": "ring",
            "type": "command"
        }
    ],
    "static_attributes": [
        {
            "name": "refStore",
            "type": "Relationship",
            "value": "urn:ngsi-ld:Store:002"
        }
    ],
    "protocol": "PDI-IoTA-UltraLight"
}

List all Provisioned Devices

This example lists all provisioned devices by making a GET request to the /iot/devices endpoint.

2️⃣3️⃣ Request:

curl -X GET \
  'http://localhost:4041/iot/devices' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Response:

The response includes all the commands and attributes mappings associated with all devices.

{
    "count": 5,
    "devices": [
      {
          "device_id": "bell002",
          "service": "openiot",
          "service_path": "/",
          "entity_name": "urn:ngsi",
          "entity_type": "Bell",
          "endpoint": "http://iot-sensors:3001/iot/bell002",
          "transport": "HTTP",
          "attributes": [],
          "lazy": [],
          "commands": [
              {
                  "object_id": "ring",
                  "name": "ring",
                  "type": "command"
              }
          ],
          "static_attributes": [
              {
                  "name": "refStore",
                  "type": "Relationship",
                  "value": "urn:ngsi-ld:Store:002"
              }
          ],
          "protocol": "PDI-IoTA-UltraLight"
      },
      etc...
    ]
}

Update a Provisioned Device

This example updates an existing provisioned device by making a PUT request to the /iot/devices/<device-id> endpoint.

2️⃣4️⃣ Request:

curl -iX PUT \
  'http://localhost:4041/iot/devices/bell002' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "entity_type": "IoT-Device"
}'

Delete a Provisioned Device

This example removes a provisioned device by making a DELETE request to the /iot/devices/<device-id> endpoint.

The device attributes will no longer be mapped and commands can no longer be sent to the device. If the device is making active measurements, they will still be handled with default values if the associated service has not been deleted.

2️⃣5️⃣ Request:

curl -iX DELETE \
  'http://localhost:4041/iot/devices/bell002' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /'

Next Steps

Want to learn how to add more complexity to your application by adding advanced features? You can find out by reading the other tutorials in this series

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LICENSE		LICENSE
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License

stellio-hub/tutorials.IoT-Agent

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Contents

What is an IoT Agent?

Southbound Traffic (Commands)

Northbound Traffic (Measurements)

Common Functionality

Device Monitor

Architecture

Dummy IoT Devices Configuration

IoT Agent for UltraLight 2.0 Configuration

Prerequisites

Docker

Cygwin

Start Up

Provisioning an IoT Agent

Device Monitor

Checking the IoT Agent Service Health

1️⃣ Request:

Connecting IoT Devices

Provisioning a Service Group

2️⃣ Request:

Provisioning a Sensor

3️⃣ Request:

4️⃣ Request:

5️⃣ Request:

Response:

Provisioning an Actuator via a Command

6️⃣ Request:

Provisioning an Actuator via a Bidirectional attribute

7️⃣ Request:

8️⃣ Request:

9️⃣ Request:

Response:

Provisioning a Smart Door

1️⃣0️⃣ Request:

Provisioning a Smart Lamp

1️⃣1️⃣ Request:

1️⃣2️⃣ Request:

Enabling Context Broker Commands

Ringing the Bell

1️⃣3️⃣ Request:

Opening the Smart Door

1️⃣4️⃣ Request:

Switching on the Smart Lamp

1️⃣5️⃣ Request:

Service Group CRUD Actions

Creating a Service Group

1️⃣6️⃣ Request:

Read Service Group Details

1️⃣7️⃣ Request:

Response:

List all Service Groups

1️⃣8️⃣ Request:

Response:

Update a Service Group

1️⃣9️⃣ Request:

Delete a Service Group

2️⃣0️⃣ Request:

Device CRUD Actions

Creating a Provisioned Device

2️⃣1️⃣ Request:

Read Provisioned Device Details

2️⃣2️⃣ Request:

Response:

List all Provisioned Devices

2️⃣3️⃣ Request:

Response:

Update a Provisioned Device

2️⃣4️⃣ Request:

Delete a Provisioned Device

2️⃣5️⃣ Request:

Next Steps

License

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