Eventstream definition

2025-05-18

This article provides a breakdown of the definition structure for Eventstream items.

Definition parts

This table lists the Eventstream definition parts.

Definition part path	type	Required	Description
`eventstream.json`	Eventstream (JSON)	✅	Describe the topology of Eventstream item
`eventstreamProperties.json`	EventstreamProperties (JSON)	❌	Describe Eventstream metadata
`.platform`	PlatformDetails (JSON)	❌	Describes the metadata of the item

Each definition part of an Eventstream item is constructed as follows:

Path: The file name, for example: eventstream.json
Payload Type: InlineBase64
Payload: See Example of payload content decoded from Base64

Eventstream

Describe the topology of Eventstream item.

Name	Type	Required	Description
`sources`	Array	true	Describes the data sources that can be ingested into Eventstream for processing.
`destinations`	Array	true	Describes the endpoints within Fabric where processed data can be routed to, including Lakehouse, Eventhouse, Reflex, and others.
`operators`	Array	true	Define the event processors that handle real-time data streams, such as Filter, Aggregate, Group By, and Join.
`streams`	Array	true	Describes the data streams available for subscription and analysis in the Real-time Hub. There are two types of streams: default streams and derived streams.

`eventstream.json` example

To see how to create a JSON file describing an Eventstream item, see Eventstream REST API.

{
    "sources": [
        {
            "name": "myEventHub",
            "type": "AzureEventHub",
            "properties": {
                "dataConnectionId": "cc8271ee-8f72-473d-969c-6828f5fd0d45",
                "consumerGroupName": "$Default",
                "inputSerialization": {
                    "type": "Json",
                    "properties": {
                        "encoding": "UTF8"
                    }
                }
            }
        }
    ],
    "destinations": [
        {
            "name": "myLakehouse",
            "type": "Lakehouse",
            "properties": {
                "workspaceId": "fdf52f3a-b687-41b8-8ff8-aeeca4d1edd8",
                "itemId": "737d6a97-e88c-45e1-9c39-adf1c9c4e817",
                "schema": "",
                "deltaTable": "newTable",
                "minimumRows": 100000,
                "maximumDurationInSeconds": 120,
                "inputSerialization": {
                    "type": "Json",
                    "properties": {
                        "encoding": "UTF8"
                    }
                }
            },
            "inputNodes": [
                {
                    "name": "derivedStream"
                }
            ]
        }
    ],
    "streams": [
        {
            "name": "myEventstream-stream",
            "type": "DefaultStream",
            "properties": {},
            "inputNodes": [
                {
                    "name": "myEventHub"
                }
            ]
        },
        {
            "name": "derivedStream",
            "type": "DerivedStream",
            "properties": {
                "inputSerialization": {
                    "type": "Json",
                    "properties": {
                        "encoding": "UTF8"
                    }
                }
            },
            "inputNodes": [
                {
                    "name": "GroupBy"
                }
            ]
        }
    ],
    "operators": [
        {
            "name": "GroupBy",
            "type": "GroupBy",
            "inputNodes": [
                {
                    "name": "myEventstream-stream"
                }
            ],
            "properties": {
                "aggregations": [
                    {
                        "aggregateFunction": "Average",
                        "column": {
                            "expressionType": "ColumnReference",
                            "node": null,
                            "columnName": "payload",
                            "columnPathSegments": [
                                {
                                    "field": "ts_ms"
                                }
                            ]
                        },
                        "alias": "AVG_ts_ms"
                    }
                ],
                "groupBy": [],
                "window": {
                    "type": "Tumbling",
                    "properties": {
                        "duration": {
                            "value": 5,
                            "unit": "Minute"
                        },
                        "offset": {
                            "value": 1,
                            "unit": "Minute"
                        }
                    }
                }
            }
        }
    ],
    "compatibilityLevel": "1.0"
}

To construct an Eventstream item for the API payload, you can use the GitHub template to define an Eventstream item.

EventstreamProperties

Describe Eventstream metadata.

Name	Type	Required	Description
`retentionTimeInDays`	Integer	❌	Describes the retention days of the Eventstream item. Default value is 1. Allowed value range from 1 to 90.
`eventThroughputLevel`	Enum	❌	Describes the event throughput level of the Eventstream item. Default value is Low. Allowed values are `Low`, `Medium`, `High`.

`eventstreamProperties.json` example

{
  "retentionTimeInDays": 1,
  "eventThroughputLevel": "Low"
}

Platform part

The platform payload is optional. The platform part is a file that contains the Eventstream metadata information.

Create Item with definition respects the platform file if provided.
Get Item definition always returns the platform file.
Update Item definition accepts the platform file if provided, if you set a new URL parameter updateMetadata=true.

Definition example

Here's an example of a Base64-encoded eventstream definition, where the content from Example of payload content decoded from Base64 is encoded in Base64 and placed in the payload field with the path set to eventstream.json :


{
  "displayName": "myEventstream",
  "type": "Eventstream",
  "description": "Create Eventstream item with definition",
  "definition": {
    "parts": [
      {
        "path": "eventstream.json",
        "payload": "<base64 encoded string>",
        "payloadType": "InlineBase64"
      },
      {
        "path": "eventstreamProperties.json",
        "payload": "<base64 encoded string>",
        "payloadType": "InlineBase64"
      },
      {
        "path": ".platform",
        "payload": "ZG90UGxhdGZvcm1CYXNlNjRTdHJpbmc=",
        "payloadType": "InlineBase64"
      }
    ]
  }
}

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