In Azure Web PubSub, How to receive messages in backend microservice for processing

Question

In Azure Web PubSub, How to receive messages in backend microservice for processing

Dheeraj Awale 21

Requirement:

My clients are using simple WebSocket connection to send messages. I want to receive these messages inside my backend .NET 8 web api and process them further to send fine-tuned data to some distributed cache services.

From documentation, I only understood that I can use backend to only send the Access URL with token to clients, and Hubs are for dealing with events only (not messages).

I don't see how to receive messages in the backend service itself, but I guess I will need to use 'WebPubSubClient' in backend service itself to receive & process messages.

Doubt:

For receiving messages, how to set up a WebSocket connection from backend service?
If not, Is it right approach to use Client SDK to receive messages in web api service (probably using it in continuous running hosted service) ?

Bruce (SqlWork.com) 79,101 Reputation points Volunteer Moderator

2025-01-10T18:53:50.1966667+00:00

in general a websocket connection is persistent connection rather than a typical http request/response. It is a 2 way stream with no formal packet definition. Part of designing a websocket app is defining the packet structures.

signal/r is a communication library and protocol built on websockets. It implements common HUBs for the server side and supports packet routing. unless your clients are already using signal/r this is not an option.

you can easily code to receive raw messages. You code would replace the echo method:

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/websockets?view=aspnetcore-9.0

your clients will need to tell you what the packets structure is and any required protocol packets.

as hosting a websocket application requires a persistent connections to multiple clients, and typically there are dedicated resources for each connection, which is active for the life of the connection. so a websocket app ties up more resources than a standard website (which typically have a 90 second connection time limit) thus require a different hosting requirement. But azure web apps support websockets by default now.

the Azure Web PubSub is an optimized hosting option for websocket applications. but it does not control how the app is developed or tools, but supplies a library to simplify websocket programming. it supports .net, node, python, java and azure functions (via hooks).
Dheeraj Awale 21 Reputation points

2025-01-13T04:18:33.19+00:00

the Azure Web PubSub is an optimized hosting option for websocket applications. but it does not control how the app is developed or tools, but supplies a library to simplify websocket programming. it supports .net, node, python, java and azure functions (via hooks).

In our case, clients already have a pure websocket library in their language. They don't want to rely on azure web pub library and just need to start websocket connection via their library (which is still a websocket library). So, what do you think about this?

Is it possible to not use this pubsub specific library and still use the service?

signal/r is a communication library and protocol built on websockets. It implements common HUBs for the server side and supports packet routing. unless your clients are already using signal/r this is not an option.

This is not an option for me, clients strictly don't want to use 'yet another' sdk/library for websockets.
Bruce (SqlWork.com) 79,101 Reputation points Volunteer Moderator

2025-01-14T17:15:16.1933333+00:00

your question is not clear.

websocket is peer to peer. implementing common hubs or message broadcast is a framework on top websockets. signal/r and the Web PubSub implement a framework to support multiple broadcast.

are you trying to connect to an existing websocket applications or supply a new websocket application.

2 answers

Your answer

Bruce (SqlWork.com) 79,101 Reputation points Volunteer Moderator

2025-01-10T18:53:50.1966667+00:00

in general a websocket connection is persistent connection rather than a typical http request/response. It is a 2 way stream with no formal packet definition. Part of designing a websocket app is defining the packet structures.

signal/r is a communication library and protocol built on websockets. It implements common HUBs for the server side and supports packet routing. unless your clients are already using signal/r this is not an option.

you can easily code to receive raw messages. You code would replace the echo method:

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/websockets?view=aspnetcore-9.0

your clients will need to tell you what the packets structure is and any required protocol packets.

as hosting a websocket application requires a persistent connections to multiple clients, and typically there are dedicated resources for each connection, which is active for the life of the connection. so a websocket app ties up more resources than a standard website (which typically have a 90 second connection time limit) thus require a different hosting requirement. But azure web apps support websockets by default now.

the Azure Web PubSub is an optimized hosting option for websocket applications. but it does not control how the app is developed or tools, but supplies a library to simplify websocket programming. it supports .net, node, python, java and azure functions (via hooks).
Dheeraj Awale 21 Reputation points

2025-01-13T04:18:33.19+00:00

the Azure Web PubSub is an optimized hosting option for websocket applications. but it does not control how the app is developed or tools, but supplies a library to simplify websocket programming. it supports .net, node, python, java and azure functions (via hooks).

In our case, clients already have a pure websocket library in their language. They don't want to rely on azure web pub library and just need to start websocket connection via their library (which is still a websocket library). So, what do you think about this?

Is it possible to not use this pubsub specific library and still use the service?

signal/r is a communication library and protocol built on websockets. It implements common HUBs for the server side and supports packet routing. unless your clients are already using signal/r this is not an option.

This is not an option for me, clients strictly don't want to use 'yet another' sdk/library for websockets.
Bruce (SqlWork.com) 79,101 Reputation points Volunteer Moderator

2025-01-14T17:15:16.1933333+00:00

your question is not clear.

websocket is peer to peer. implementing common hubs or message broadcast is a framework on top websockets. signal/r and the Web PubSub implement a framework to support multiple broadcast.

are you trying to connect to an existing websocket applications or supply a new websocket application.

Answer 1

Laxman Reddy Revuri 5,475 Microsoft External Staff Moderator

Hi @dheeraj awale
Yes, you can use Azure Web PubSub without the Microsoft SDK by connecting directly via WebSockets. Clients can use any WebSocket library to connect using a Client Access URL, which includes an access token for authentication.
The URL format is: wss://<service_name>.webpubsub.azure.com/client/hubs/<hub_name>?access_token=<token>.
Clients can then send and receive messages in real-time, with custom message handling based on the defined packet structure.
By not using the Azure SDK, you lose features like automatic reconnections and simplified group management, requiring manual handling. Clients must be aware of the message packet structure for proper communication. Additionally, you’ll need to manage scalability and connection handling on your own, as Azure Web PubSub won't handle it for you.

Please accept as "Yes" if the answer provided is useful , so that you can help others in the community looking for remediation for similar issues.

Laxman Reddy Revuri 5,475 Reputation points Microsoft External Staff Moderator

2025-01-24T05:08:20.55+00:00

Hi @dheeraj awale
Following up to see if you have chance to check my previous response and help us with requested information to check and assist you further on this.
Laxman Reddy Revuri 5,475 Reputation points Microsoft External Staff Moderator

2025-01-27T03:32:47.8166667+00:00

Hi @dheeraj awale
Following up to see if you have chance to check my previous response and help us with requested information to check and assist you further on this.

Answer 2

Hi Dheeraj,

What you’re experiencing relates to receiving messages from clients using simple WebSocket connections in your backend .NET 8 web API for further processing. This typically occurs when you want to process real-time data server-side, but your clients prefer not to use the Azure Web PubSub SDK and instead rely on standard WebSocket libraries.

Here’s how you can troubleshoot and resolve it:

You can have your backend service connect to Azure Web PubSub using a standard WebSocket client, just like your other clients. Use the Client Access URL (which includes the access token) to establish the connection. This allows your backend to receive and process messages in real time, without needing the Azure SDK.
Make sure to define a clear message structure so both your clients and backend understand the data being exchanged.
Be aware that by not using the SDK, you’ll need to handle reconnections and group management manually.

You can also find a detailed walkthrough in our documentation here:

Azure Web PubSub Documentation

I hope this helps you get things back on track quickly! If you agree with my suggestion, feel free to interact with the system accordingly!

Raymond Huynh (WICLOUD CORPORATION) 620 Reputation points Microsoft External Staff

2025-08-01T10:05:00.94+00:00

Feel free to ask if you need any help!
Raymond Huynh (WICLOUD CORPORATION) 620 Reputation points Microsoft External Staff

2025-08-08T10:36:26.0966667+00:00

Hi,

Just checking in. I haven’t heard back from you for a while, I hope everything works out as you expected. I understand things can get busy or priorities may shift.

If you’re still experiencing the issue or need further support, feel free to jump back in at any time. I will always be here and happy to help.

Wishing you all the best with your work!

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In Azure Web PubSub, How to receive messages in backend microservice for processing

2 answers

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