This article describes how to configure data export to send data to the Blob Storage service.
Use this feature to continuously export filtered and enriched IoT data from your IoT Central application. Data export pushes changes in near real time to other parts of your cloud solution for warm-path insights, analytics, and storage.
For example, you can:
Continuously export telemetry, property changes, device connectivity, device lifecycle, device template lifecycle, and audit log data in JSON format in near real time.
Filter the data streams to export data that matches custom conditions.
Enrich the data streams with custom values and property values from the device.
When you turn on data export, you get only the data from that moment onward. To retain more historical data, turn on data export early. To manually export data from times when data export was turned off, see How to use the IoT Central REST API to query devices.
Bemærk
In some circumstances it could take up to 60 seconds for the messages to be exported. This time is measured from when IoT Central receives the message from the underlying IoT hub to when the message is delivered to the destination endpoint.
Prerequisites
To use data export features, you must have the Data export permission.
IoT Central exports data once per minute, with each file containing the batch of changes since the previous export. Exported data is saved in JSON format. The default paths to the exported data in your storage account are:
When you configure a managed identity, the configuration includes a scope and a role:
The scope defines where you can use the managed identity. For example, you can use an Azure resource group as the scope. In this case, both the IoT Central application and the destination must be in the same resource group.
The role defines what permissions the IoT Central application is granted in the destination service. For example, for an IoT Central application to send data to an event hub, the managed identity needs the Azure Event Hubs Data Sender role assignment.
The following video provides more information about system assigned managed identities:
Forsigtigt
To export to blob storage, don't use the Storage Account Contributor as shown in the video. Use the Storage Blob Data Contributor role instead.
This article shows how to create a managed identity using the Azure CLI. You can also use the Azure portal to create a manged identity.
If you don't have an existing Azure storage account to export to, run the following script in the Azure Cloud Shell bash environment. The script creates a resource group, Azure Storage account, and blob container. The script then enables the managed identity for your IoT Central application and assigns the role it needs to access your storage account:
Azure CLI
# Replace the storage account name with your own unique value.
SA=yourstorageaccount$RANDOM# Replace the IoT Central app name with the name of your# IoT Central application.
CA=your-iot-central-app
CN=exportdata
RG=centralexportresources
LOCATION=eastus
az group create -n$RG--location$LOCATION
SAID=$(az storage account create --name$SA--resource-group$RG--location$LOCATION--sku Standard_LRS --query"id"--output tsv)
az storage container create --account-name$SA--resource-group$RG--name$CN# This assumes your IoT Central application is in the # default `IOTC` resource group.az iot central app identity assign --name$CA--resource-group IOTC --system-assigned
PI=$(az iot central app identity show --name$CA--resource-group IOTC --query"principalId"--output tsv)
az role assignment create --assignee$PI--role"Storage Blob Data Contributor"--scope$SAIDaz role assignment list --assignee$PI--all-o table
echo "Endpoint URI: https://$SA.blob.core.windows.net/"
echo "Container: $CN"
To create the Blob Storage destination in IoT Central on the Data export page:
Select + New destination.
Select Azure Blob Storage as the destination type.
Select System-assigned managed identity as the authorization type.
Enter the endpoint URI for your storage account and the case-sensitive container name. An endpoint URI looks like: https://contosowaste.blob.core.windows.net.
If you don't have an existing Azure storage account to export to, run the following script in the Azure Cloud Shell bash environment. The script creates a resource group, Azure Storage account, and blob container. It then prints the connection string to use when you configure the data export in IoT Central:
Azure CLI
# Replace the storage account name with your own unique value
SA=yourstorageaccount$RANDOM
CN=exportdata
RG=centralexportresources
LOCATION=eastus
az group create -n$RG--location$LOCATIONaz storage account create --name$SA--resource-group$RG--location$LOCATION--sku Standard_LRS
az storage container create --account-name$SA--resource-group$RG--name$CN
CS=$(az storage account show-connection-string--resource-group$RG--name$SA--query"connectionString"--output tsv)
echo "Storage connection string: $CS"
To create the Blob Storage destination in IoT Central on the Data export page:
Select + New destination.
Select Azure Blob Storage as the destination type.
Select Connection string as the authorization type.
Paste in the connection string for your Blob Storage resource, and enter the case-sensitive container name if necessary.
Select Save.
Set up a data export
Now that you have a destination to export your data to, set up data export in your IoT Central application:
Sign in to your IoT Central application.
In the left pane, select Data export.
Tip
If you don't see Data export in the left pane, then you don't have permissions to configure data export in your app. Talk to an administrator to set up data export.
Select + New export.
Enter a display name for your new export, and make sure the data export is Enabled.
Choose the type of data to export. The following table lists the supported data export types:
Data type
Description
Data format
Telemetry
Export telemetry messages from devices in near-real time. Each exported message contains the full contents of the original device message, normalized.
Export changes to device and cloud properties in near-real time. For read-only device properties, changes to the reported values are exported. For read-write properties, both reported and desired values are exported.
Optionally, add filters to reduce the amount of data exported. There are different types of filter available for each data export type:
Type of data
Available filters
Telemetry
Filter by device name, device ID, device template, and if the device is simulated
Filter stream to only contain telemetry that meets the filter conditions
Filter stream to only contain telemetry from devices with properties matching the filter conditions
Filter stream to only contain telemetry that has message properties meeting the filter condition. Message properties (also known as application properties) are sent in a bag of key-value pairs on each telemetry message. To create a message property filter, enter the message property key you're looking for, and specify a condition. Only telemetry messages with properties that match the specified filter condition are exported. Learn more about application properties from IoT Hub docs
Property changes
Filter by device name, device ID, device template, and if the device is simulated
Filter stream to only contain property changes that meet the filter conditions
Device connectivity
Filter by device name, device ID, device template, organizations, and if the device is simulated
Filter stream to only contain changes from devices with properties matching the filter conditions
Device lifecycle
Filter by device name, device ID, device template, and if the device is provisioned, enabled, or simulated
Filter stream to only contain changes from devices with properties matching the filter conditions
Device template lifecycle
Filter by device template
Audit logs
N/A
Optionally, enrich exported messages with extra key-value pair metadata. The following enrichments are available for the telemetry, property changes, device connectivity, and device lifecycle data export types:
Custom string: Adds a custom static string to each message. Enter any key, and enter any string value.
Property, which adds to each message:
Device metadata such as device name, device template name, enabled, organizations, provisioned, and simulated.
The current device reported property or cloud property value to each message. If the exported message is from a device that doesn't have the specified property, the exported message doesn't get the enrichment.
Configure the export destination:
Select + Destination to add a destination that you've already created or select Create a new one.
Select + Destination to add up to five destinations to a single export.
When you've finished setting up your export, select Save. After a few minutes, your data appears in your destinations.
Monitor your export
In IoT Central, the Data export page lets you check the status of your exports. You can also use Azure Monitor to see how much data you're exporting and any export errors. You can access export and device health metrics in charts in the Azure portal by using, the REST API, queries in PowerShell, or the Azure CLI. Currently, you can monitor the following data export metrics in Azure Monitor:
Number of messages incoming to export before filters are applied.
Number of messages that pass through filters.
Number of messages successfully exported to destinations.
The following sections describe the formats of the exported data:
Telemetry format
Each exported message contains a normalized form of the full message the device sent in the message body. The message is in JSON format and encoded as UTF-8. Information in each message includes:
applicationId: The ID of the IoT Central application.
messageSource: The source for the message - telemetry.
deviceId: The ID of the device that sent the telemetry message.
schema: The name and version of the payload schema.
templateId: The ID of the device template assigned to the device.
enqueuedTime: The time at which IoT Central received this message.
enrichments: Any enrichments set up on the export.
module: The IoT Edge module that sent this message. This field only appears if the message came from an IoT Edge module.
component: The component that sent this message. This field only appears if the capabilities sent in the message were modeled as a component in the device template
messageProperties: Other properties that the device sent with the message. These properties are sometimes referred to as application properties. Learn more from IoT Hub docs.
For Blob Storage, messages are batched and exported once per minute.
The following example shows an exported telemetry message:
Telemetry messages have properties for metadata as well as the telemetry payload. The previous snippet shows examples of system messages such as deviceId and enqueuedTime. To learn more about the system message properties, see System Properties of device-to-cloud IoT Hub messages.
You can add properties to telemetry messages if you need to add custom metadata to your telemetry messages. For example, you need to add a timestamp when the device creates the message.
The following code snippet shows how to add the iothub-creation-time-utc property to the message when you create it on the device:
Vigtigt
The format of this timestamp must be UTC with no timezone information. For example, 2021-04-21T11:30:16Z is valid, 2021-04-21T11:30:16-07:00 is invalid.
Each message or record represents changes to device and cloud properties. Information in the exported message includes:
applicationId: The ID of the IoT Central application.
messageSource: The source for the message - properties.
messageType: Either cloudPropertyChange, devicePropertyDesiredChange, or devicePropertyReportedChange.
deviceId: The ID of the device that sent the telemetry message.
schema: The name and version of the payload schema.
enqueuedTime: The time at which IoT Central detected this change.
templateId: The ID of the device template assigned to the device.
properties: An array of properties that changed, including the names of the properties and values that changed. The component and module information is included if the property is modeled within a component or an IoT Edge module.
enrichments: Any enrichments set up on the export.
For Blob Storage, messages are batched and exported once per minute.
The following snippet shows a property change message exported to Blob Storage:
Each message or record represents one change to a single device. Information in the exported message includes:
applicationId: The ID of the IoT Central application.
messageSource: The source for the message - deviceLifecycle.
messageType: The type of change that occurred. One of: registered, deleted, provisioned, enabled, disabled, displayNameChanged, and deviceTemplateChanged.
deviceId: The ID of the device that was changed.
schema: The name and version of the payload schema.
templateId: The ID of the device template assigned to the device.
enqueuedTime: The time at which this change occurred in IoT Central.
enrichments: Any enrichments set up on the export.
For Blob Storage, messages are batched and exported once per minute.
The following example shows an exported device lifecycle message received in Azure Blob Storage.
Each audit log message represents a user-initiated change to an auditable entity inside the IoT Central application. Information in the exported message includes:
actor: Information about the user who modified the entity.
applicationId: The ID of the IoT Central application.
messageSource: The source for the message - audit.
messageType: The type of change that occurred. One of: updated, created, deleted.
updated: Only present if messageType is updated. Provides more detail about the update.
resource: Details of the modified entity.
schema: The name and version of the payload schema.
deviceId: The ID of the device that was changed.
enqueuedTime: The time at which this change occurred in IoT Central.
enrichments: Any enrichments set up on the export.
The following example shows an exported audit log message received in Azure Blob Storage:
IoT devices send data in various formats that you might need to transform. This article describes how to transform data both on the way in and out of IoT Central.
This tutorial shows you how Azure IoT Central rules let you monitor your devices in near real time and automatically invoke actions when a rule triggers.