Post HTTP messages to a MQTT TopicSpace in Event Grid Namespace

Question

Post HTTP messages to a MQTT TopicSpace in Event Grid Namespace

BV 25

Is it possible to post messages to a TopicSpace in Event Grid Namespace?

We would like to publish messages to MQTT TopicSpace on the Event Grid Namespace from an Azure Logic App, which can then be consumed by subscribers:

When trying the following HTTPS endpoint: https://<event grid namespace>.<region>.ts.eventgrid.azure.net/mqtt, it raises an error "api-version" needed or Unsupported API version.

So it is possible

To post messages from Logic App
Use HTTPS endpoint to do this (if so, what is the syntax for the REST API Post)?
will this be supported in the future?

Sai Prabhu Naveen Parimi 3,725 Reputation points Microsoft External Staff Moderator

2025-06-23T22:20:06.76+00:00
@BV

It sounds like you're trying to publish messages from an Azure Logic App to a TopicSpace in your Event Grid Namespace using MQTT, but you're encountering an issue with the API version when hitting the HTTPS endpoint.

Here's a breakdown of what you can do:

Posting Messages from a Logic App: You can indeed publish messages to an MQTT TopicSpace from an Azure Logic App by calling the appropriate REST API endpoint. However, make sure you're using the correct syntax that includes the required "api-version" parameter in your request. Typically, this should look something like:
POST https://<event grid namespace>.<region>.ts.eventgrid.azure.net/mqtt?api-version=2023-01-01
(Make sure to replace 2023-01-01 with the latest API version if it's updated.)

Endpoint Syntax: In your Logic App, you would generally use the "HTTP" action to send the POST request. The body of the request should contain the message you want to publish, likely formatted as JSON. Example:
{ "message": "Your message here", "topic": "contosotopics/topic1" }
Make sure to set the appropriate authentication headers if required.

Future Support: As for whether this will be supported in the future, the Azure Event Grid team continuously updates and improves their services based on user feedback and needs. It’s best to stay updated on the official Azure updates blog or check the release notes for any announcements regarding new features or support.

I hope this helps! If you could provide more details on the specific Logic App configuration you're using or any other error messages you might be seeing, that would help clarify the issue further.
BV 25 Reputation points

2025-06-24T09:00:22.13+00:00

Thanks for the response @Sai Prabhu Naveen Parimi It is good to know that Logic Apps can publish messages to TopicSpaces.

I was not able to find the correct version of the API before (and now). This endpoint seems to be missing from the Azure Event Grid Data Plane API documentation.

Please would you be able to point me to the documentation for this API?

P.S. "?api-version=2023-01-01" throws an error "Unsupported API version" - I am assuming you'd used that as an example?

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Sai Prabhu Naveen Parimi 3,725 Reputation points Microsoft External Staff Moderator

2025-06-23T22:20:06.76+00:00

@BV

It sounds like you're trying to publish messages from an Azure Logic App to a TopicSpace in your Event Grid Namespace using MQTT, but you're encountering an issue with the API version when hitting the HTTPS endpoint.

Here's a breakdown of what you can do:

Posting Messages from a Logic App: You can indeed publish messages to an MQTT TopicSpace from an Azure Logic App by calling the appropriate REST API endpoint. However, make sure you're using the correct syntax that includes the required "api-version" parameter in your request. Typically, this should look something like:
POST https://<event grid namespace>.<region>.ts.eventgrid.azure.net/mqtt?api-version=2023-01-01
(Make sure to replace 2023-01-01 with the latest API version if it's updated.)

Endpoint Syntax: In your Logic App, you would generally use the "HTTP" action to send the POST request. The body of the request should contain the message you want to publish, likely formatted as JSON. Example:
{ "message": "Your message here", "topic": "contosotopics/topic1" }
Make sure to set the appropriate authentication headers if required.

Future Support: As for whether this will be supported in the future, the Azure Event Grid team continuously updates and improves their services based on user feedback and needs. It’s best to stay updated on the official Azure updates blog or check the release notes for any announcements regarding new features or support.

I hope this helps! If you could provide more details on the specific Logic App configuration you're using or any other error messages you might be seeing, that would help clarify the issue further.
BV 25 Reputation points

2025-06-24T09:00:22.13+00:00

Thanks for the response @Sai Prabhu Naveen Parimi It is good to know that Logic Apps can publish messages to TopicSpaces.

I was not able to find the correct version of the API before (and now). This endpoint seems to be missing from the Azure Event Grid Data Plane API documentation.

Please would you be able to point me to the documentation for this API?

P.S. "?api-version=2023-01-01" throws an error "Unsupported API version" - I am assuming you'd used that as an example?

Answer 1

Seth Shanmugam 80 Microsoft Employee

HTTP Publish for the Event Grid MQTT broker is currently in Private Preview and is planned to move to Public Preview around the end of July this year.

If the customer would like to try out this capability before the Public Preview, please share their Tenant ID and Subscription ID so we can allowlist them for the Private Preview and provide the necessary guidance and documentation to get started.

BV 25 Reputation points

2025-07-01T08:15:34.1366667+00:00

Thanks for confirming that! Very useful. It would be great to get this tested and I'll share the details with our MS account contact.
Jonas 21 Reputation points

2025-08-28T19:02:17.34+00:00

Hi Seth, has the feature moved to public preview yet? I see the documentation mentioning the preview but it is unclear if still in private preview?

Answer 2

Sander van de Velde | MVP 36,941 MVP Volunteer Moderator

Hello @BV,

welcome to this moderated Azure community forum.

it seems you are looking at documentation of an endpoint that is use to post message to an EventGrid namespace topic, not an MQTT topic (space).

Publish a single Cloud Event to a namespace topic.

To connect to the MQTT broker, several ways to authenticate are described here.

I have no experience with connecting to the Topic space directly, though.

I used the alternative solution to host an MQTT client in a container instance to get messages being sent as MQTT messages from the cloud.

If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.

BV 25 Reputation points

2025-06-25T06:18:12.0066667+00:00

Thanks for the reply. I am looking to see if there is a way to post messages to a Topic Space directly
BV 25 Reputation points

2025-06-25T06:29:51.4466667+00:00

Thanks for your reply. I am looking to see if there is a way to post messages directly to Topic Space (or confirmation that it is not possible)
Sai Prabhu Naveen Parimi 3,725 Reputation points Microsoft External Staff Moderator

2025-06-30T08:44:11.43+00:00

Hello BV

Thanks for the additional context.

Based on current documentation, it appears that there is no direct REST API or HTTPS endpoint available to publish messages to an MQTT Topic Space in an Event Grid Namespace.

The only documented REST API endpoint available is to publish a message to a namespace topic, as outlined here: Publish Cloud Event - REST API (Azure Event Grid)

That endpoint is intended for Event Grid topics, not MQTT Topic Spaces.

However, there is a sample provided here that demonstrates how to send MQTT messages using JWT authentication, which may help in publishing to a Topic Space: Azure-Samples/MqttApplicationSamples – jwt_authentication Scenario

If your goal is to publish messages to a Topic Space from a Logic App or another HTTP-based service, one possible workaround is to:

Run an MQTT client (e.g., in an Azure Container Instance or Function App),

Expose it through an internal API,

And let Logic Apps call that intermediary to publish to the MQTT Topic Space.

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Post HTTP messages to a MQTT TopicSpace in Event Grid Namespace

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