CloudEvents v1.0 schema with Azure Event Grid

Azure Event Grid natively supports events in the JSON implementation of CloudEvents v1.0 and HTTP protocol binding. CloudEvents is an open specification for describing event data.

CloudEvents simplifies interoperability by providing a common event schema for publishing, and consuming cloud based events. This schema allows for uniform tooling, standard ways of routing & handling events, and universal ways of deserializing the outer event schema. With a common schema, you can more easily integrate work across platforms.

CloudEvents is being built by several collaborators, including Microsoft, through the Cloud Native Computing Foundation. It's currently available as version 1.0.

This article describes CloudEvents schema with Event Grid.

Sample event using CloudEvents schema

Here's an example of an Azure Blob Storage event in the CloudEvents format:

{
    "specversion": "1.0",
    "type": "Microsoft.Storage.BlobCreated",  
    "source": "/subscriptions/{subscription-id}/resourceGroups/{resource-group}/providers/Microsoft.Storage/storageAccounts/{storage-account}",
    "id": "9aeb0fdf-c01e-0131-0922-9eb54906e209",
    "time": "2019-11-18T15:13:39.4589254Z",
    "subject": "blobServices/default/containers/{storage-container}/blobs/{new-file}",    
    "data": {
        "api": "PutBlockList",
        "clientRequestId": "4c5dd7fb-2c48-4a27-bb30-5361b5de920a",
        "requestId": "9aeb0fdf-c01e-0131-0922-9eb549000000",
        "eTag": "0x8D76C39E4407333",
        "contentType": "image/png",
        "contentLength": 30699,
        "blobType": "BlockBlob",
        "url": "https://gridtesting.blob.core.windows.net/testcontainer/{new-file}",
        "sequencer": "000000000000000000000000000099240000000000c41c18",
        "storageDiagnostics": {
            "batchId": "681fe319-3006-00a8-0022-9e7cde000000"
        }
    }
}

A detailed description of the available fields, their types, and definitions in CloudEvents v1.0 is available here.

The headers values for events delivered in the CloudEvents schema and the Event Grid schema are the same except for content-type. For CloudEvents schema, that header value is "content-type":"application/cloudevents+json; charset=utf-8". For Event Grid schema, that header value is "content-type":"application/json; charset=utf-8".

Event Grid for CloudEvents

You can use Event Grid for both input and output of events in CloudEvents schema. You can use CloudEvents for system events, like Blob Storage events and IoT Hub events, and custom events. In addition to supporting CloudEvents, Event Grid supports a proprietary, nonextensible, yet fully functional Event Grid event format. The following table describes the transformation supported when using CloudEvents and Event Grid formats as an input schema in topics and as an output schema in event subscriptions. An Event Grid output schema can't be used when using CloudEvents as an input schema because CloudEvents supports extension attributes that aren't supported by the Event Grid schema.

Input schema	Output schema
CloudEvents format	CloudEvents format
Event Grid format	CloudEvents format
Event Grid format	Event Grid format

For all event schemas, Event Grid requires validation when publishing to an Event Grid topic and when creating an event subscription. For more information, see Event Grid security and authentication.

Next steps

See How to use CloudEvents v1.0 schema with Event Grid.