Publish to namespace topics and consume events in Azure Event Grid

Članak
02/20/2024

This article provides a quick introduction to pull delivery using the curl bash shell command to publish, receive, and acknowledge events. Event Grid resources are created using CLI commands. This article is suitable for a quick test of the pull delivery functionality. For sample code using the data plane SDKs, see the .NET or the Java samples. For Java, we provide the sample code in two articles: publish events and receive events quickstarts. For more information about the pull delivery model, see the concepts and pull delivery overview articles.

If you don't have an Azure subscription, create an Azure free account before you begin.

Prerequisites

Use the Bash environment in Azure Cloud Shell. For more information, see Quickstart for Bash in Azure Cloud Shell.
If you prefer to run CLI reference commands locally, install the Azure CLI. If you're running on Windows or macOS, consider running Azure CLI in a Docker container. For more information, see How to run the Azure CLI in a Docker container.
- If you're using a local installation, sign in to the Azure CLI by using the az login command. To finish the authentication process, follow the steps displayed in your terminal. For other sign-in options, see Sign in with the Azure CLI.
- When you're prompted, install the Azure CLI extension on first use. For more information about extensions, see Use extensions with the Azure CLI.
- Run az version to find the version and dependent libraries that are installed. To upgrade to the latest version, run az upgrade.

This article requires version 2.0.70 or later of the Azure CLI. If using Azure Cloud Shell, the latest version is already installed.

Create a resource group

Create an Azure resource group with the az group create command. You use this resource group to contain all resources created in this article.

The general steps to use Cloud Shell to run commands are:

Select Open Cloud Shell to see an Azure Cloud Shell window on the right pane.
Copy the command and paste into the Azure Cloud Shell window.
Press ENTER to run the command.

Declare a variable to hold the name of an Azure resource group. Specify a name for the resource group by replacing <your-resource-group-name> with a value you like.
```
resource_group="<your-resource-group-name>"
```
Create a resource group. Change the location as you see fit.
```
az group create --name $resource_group --location eastus
```

Enable the Event Grid resource provider

If you haven't previously used Event Grid in your Azure subscription, you might need to register the Event Grid resource provider. Run the following command to register the provider:
```
az provider register --namespace Microsoft.EventGrid
```
It might take a moment for the registration to finish. To check the status, run the following command:
```
az provider show --namespace Microsoft.EventGrid --query "registrationState"
```
When registrationState is Registered, you're ready to continue.

Create a namespace

An Event Grid namespace provides a user-defined endpoint to which you post your events. The following example creates a namespace in your resource group using Bash in Azure Cloud Shell. The namespace name must be unique because it's part of a Domain Name System (DNS) entry. A namespace name should meet the following rules:

It should be between 3-50 characters.
It should be regionally unique.
Only allowed characters are a-z, A-Z, 0-9 and -
It shouldn't start with reserved key word prefixes like Microsoft, System or EventGrid.

Declare a variable to hold the name for your Event Grid namespace. Specify a name for the namespace by replacing <your-namespace-name> with a value you like.
```
namespace="<your-namespace-name>"
```
Create a namespace. You might want to change the location where it's deployed.
```
az eventgrid namespace create -g $resource_group -n $namespace -l eastus
```

Create a namespace topic

Create a topic that's used to hold all events published to the namespace endpoint.

Declare a variable to hold the name for your namespace topic. Specify a name for the namespace topic by replacing <your-topic-name> with a value you like.
```
topic="<your-topic-name>"
```

Create your namespace topic:

az eventgrid namespace topic create -g $resource_group -n $topic --namespace-name $namespace

Create an event subscription

Create an event subscription setting its delivery mode to queue, which supports pull delivery. For more information on all configuration options,see the latest Event Grid control plane REST API.

Declare a variable to hold the name for an event subscription to your namespace topic. Specify a name for the event subscription by replacing <your-event-subscription-name> with a value you like.
```
event_subscription="<your-event-subscription-name>"
```

Create an event subscription to the namespace topic:

az eventgrid namespace topic event-subscription create -g $resource_group --topic-name $topic -n $event_subscription --namespace-name $namespace --delivery-configuration "{deliveryMode:Queue,queue:{receiveLockDurationInSeconds:300,maxDeliveryCount:4,eventTimeToLive:P1D}}"

Send events to your topic

Now, send a sample event to the namespace topic by following steps in this section.

List namespace access keys

Get the access keys associated with the namespace you created. You use one of them to authenticate when publishing events. To list your keys, you need the full namespace resource ID first. Get it by running the following command:
```
namespace_resource_id=$(az eventgrid namespace show -g $resource_group -n $namespace --query "id" --output tsv)
```

Get the first key from the namespace:

key=$(az eventgrid namespace list-key -g $resource_group --namespace-name $namespace --query "key1" --output tsv)

Publish an event

Retrieve the namespace hostname. You use it to compose the namespace HTTP endpoint to which events are sent. The following operations were first available with API version 2023-06-01-preview.

publish_operation_uri="https://"$(az eventgrid namespace show -g $resource_group -n $namespace --query "topicsConfiguration.hostname" --output tsv)"/topics/"$topic:publish?api-version=2023-06-01-preview

Create a sample CloudEvents compliant event:

event=' { "specversion": "1.0", "id": "'"$RANDOM"'", "type": "com.yourcompany.order.ordercreatedV2", "source" : "/mycontext", "subject": "orders/O-234595", "time": "'`date +%Y-%m-%dT%H:%M:%SZ`'", "datacontenttype" : "application/json", "data":{ "orderId": "O-234595", "url": "https://yourcompany.com/orders/o-234595"}} '

The data element is the payload of your event. Any well-formed JSON can go in this field. For more information on properties (also known as context attributes) that can go in an event, see the CloudEvents specifications.

Use CURL to send the event to the topic. CURL is a utility that sends HTTP requests.

curl -X POST -H "Content-Type: application/cloudevents+json" -H "Authorization:SharedAccessKey $key" -d "$event" $publish_operation_uri

Receive the event

You receive events from Event Grid using an endpoint that refers to an event subscription.

Compose that endpoint by running the following command:

receive_operation_uri="https://"$(az eventgrid namespace show -g $resource_group -n $namespace --query "topicsConfiguration.hostname" --output tsv)"/topics/"$topic/eventsubscriptions/$event_subscription:receive?api-version=2023-06-01-preview

Submit a request to consume the event:

curl -X POST -H "Content-Type: application/json" -H "Authorization:SharedAccessKey $key" $receive_operation_uri

Acknowledge an event

After you receive an event, you pass that event to your application for processing. Once you have successfully processed your event, you no longer need that event to be in your event subscription. To instruct Event Grid to delete the event, you acknowledge it using its lock token that you got on the receive operation's response.

In the previous step, you should have received a response that includes a brokerProperties object with a lockToken property. Copy the lock token value and set it on an environment variable:
```
lockToken="<paste-the-lock-token-here>"
```
Now, build the acknowledge operation payload, which specifies the lock token for the event you want to be acknowledged.
```
acknowledge_request_payload=' { "lockTokens": ["'$lockToken'"]} '
```

Proceed with building the string with the acknowledge operation URI:

acknowledge_operation_uri="https://"$(az eventgrid namespace show -g $resource_group -n $namespace --query "topicsConfiguration.hostname" --output tsv)"/topics/"$topic/eventsubscriptions/$event_subscription:acknowledge?api-version=2023-06-01-preview

Finally, submit a request to acknowledge the event received:

curl -X POST -H "Content-Type: application/json" -H "Authorization:SharedAccessKey $key" -d "$acknowledge_request_payload" $acknowledge_operation_uri

If the acknowledge operation is executed before the lock token expires (300 seconds as set when we created the event subscription), you should see a response like the following example:

{"succeededLockTokens":["CiYKJDQ4NjY5MDEyLTk1OTAtNDdENS1BODdCLUYyMDczNTYxNjcyMxISChDZae43pMpE8J8ovYMSQBZS"],"failedLockTokens":[]}

Next steps

To learn more about pull delivery model, see Pull delivery overview.