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Event Handling

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The device service shall be able to use at least one way to retrieve events out of the following: * PullPoint - "Pull" using the CreatePullPointSubscription and PullMessage operations * BaseNotification - "Push" using Notify, Subscribe and Renew operations from WSBaseNotification

The spec can refer to https://www.onvif.org/ver10/events/wsdl/event.wsdl and https://docs.oasis-open.org/wsn/wsn-ws_base_notification-1.3-spec-os.pdf

Define the device resources for Event Handling

Define a CameraEvent resource for device service to publish the event

Before receiving the event data from the camera, we must define a device resource for the event. 

- name: "CameraEvent"
 isHidden: true
 description: "This resource is used to send the async event reading to north bound"
 attributes:
   service: "EdgeX"
   getFunction: "CameraEvent"
 properties:
   valueType: "Object"
   readWrite: "R"

Define device resource for PullPoint

  • Define a SubscribeCameraEvent resource with PullPoint subscribeType for creating the subscription 

    - name: "SubscribeCameraEvent"
 isHidden: false
 description: "Create a subscription to subscribe the event from the camera"
 attributes:
   service: "EdgeX"
   setFunction: "SubscribeCameraEvent"
   # PullPoint | BaseNotification
   subscribeType: "PullPoint"
   defaultSubscriptionPolicy: ""
   defaultInitialTerminationTime: "PT1H"
   defaultAutoRenew: true
   defaultTopicFilter: "tns1:RuleEngine/TamperDetector"
   defaultMessageContentFilter: "boolean(//tt:SimpleItem[@Name=”IsTamper”])"
   defaultMessageTimeout: "PT5S"
   defaultMessageLimit: 10
 properties:
   valueType: "Object"
   readWrite: "W"

  • Define an UnsubscribeCameraEvent resource for unsubscribing 

    - name: "UnsubscribeCameraEvent"
 isHidden: false
 description: "Unsubscribe all event from the camera"
 attributes:
   service: "EdgeX"
   setFunction: "UnsubscribeCameraEvent"
 properties:
   valueType: "Object"
   readWrite: "W"

Define device resource for BaseNotification

  • Define a SubscribeCameraEvent resource with BaseNotification subscribeType 

    - name: "SubscribeCameraEvent"
 isHidden: false
 description: "Create a subscription to subscribe the event ..."
 attributes:
   service: "EdgeX"
   setFunction: "SubscribeCameraEvent"
   # PullPoint | BaseNotification
   subscribeType: "BaseNotification"
   defaultSubscriptionPolicy: ""
   defaultInitialTerminationTime: "PT1H"
   defaultAutoRenew: true
   defaultTopicFilter: "..."
   defaultMessageContentFilter: "..."
 properties:
   valueType: "Object"
   readWrite: "W"

  • Define a driver config BaseNotificationURL to indicate the device service network location 

    # configuration.yaml
AppCustom:
  # BaseNotificationURL indicates the device service network location (which should be accessible from onvif devices on the network), when
  # configuring an Onvif Event subscription.
  BaseNotificationURL: 'http://192.168.12.112:59984'

Device service will generate the following path for pushing event from Camera to device service: - {BaseNotificationURL}/api/v3/resource/{DeviceName}/{ResourceName} - {BaseNotificationURL}/api/v3/resource/Camera1/CameraEvent

Note

The user can also override the config from the docker-compose environment variable:

export HOST_IP=$(ifconfig eth0 | grep "inet " | awk '{ print $2 }')

environment:
   DRIVER_BASENOTIFICATIONURL: http://${HOST_IP}:59984
Then the device service can be accessed by the external camera from the other subnetwork.

Define device resource for unsubscribing the event

  - name: "UnsubscribeCameraEvent"
    isHidden: true
    description: "Unsubscribe all subscription from the camera"
    attributes:
      service: "EdgeX"
      setFunction: "UnsubscribeCameraEvent"
    properties:
      valueType: "Object"
      readWrite: "W"

Find the supported Event Topics

Finding out what notifications a camera supports and what information they contain:

curl --request GET 'http://localhost:59882/api/v3/device/name/Camera003/EventProperties'

Create a Pull Point

User can create pull point with the following command: 

curl --request PUT 'http://localhost:59882/api/v3/device/name/Camera003/PullPointSubscription' \
--header 'Content-Type: application/json' \
--data-raw '{
    "PullPointSubscription": {
        "MessageContentFilter": "boolean(//tt:SimpleItem[@Name=\"Rule\"])",
        "InitialTerminationTime": "PT120S",
        "MessageTimeout": "PT20S"
    }
}'

Note

  • Device service uses a loop to pull message, and the subscription auto-renew by camera
  • Device service create a new pull point when the pull point expired
  • User can unsubscribe the subscription, then the device service will stop the loop to pull the message and execute unsubscribe Onvif function.

Create a BaseNotification

User can create subscription, the InitialTerminationTime is required and should greater than ten seconds: 

curl --request PUT 'http://localhost:59882/api/v3/device/name/Camera003/BaseNotificationSubscription' \
--header 'Content-Type: application/json' \
--data-raw '{
    "BaseNotificationSubscription": {
        "TopicFilter": "tns1:RuleEngine/TamperDetector/Tamper",
        "InitialTerminationTime": "PT180S"
    }
}'

Note

  • Device service send Renew request every ten second before termination time
  • User can unsubscribe the subscription, then the device service stop to renew the subscription

Unsubscribe all subscriptions

The user can unsubscribe all subscriptions(PullPoint and BaseNotification) from the camera with the following command: 

curl --request PUT 'http://localhsot:59882/api/v3/device/name/Camera003/UnsubscribeCameraEvent' \
--header 'Content-Type: application/json' \
--data-raw '{
    "UnsubscribeCameraEvent": {
    }
}'