How to send SignalR multiple async messages from one function .Net 8

Question

I'm currently migrating my azure functions from .NET 6 to 8 in an isolated worker model. Below is an example of how my real code works. basically the signalR is used to send messages to the front end on the progress of a long running queue function which no longer works on .NET 8 because I can only return one single message as a return SignalRMessageAction. is there a way to send more than one messages in a sequential order? either through separate queues or call another signalR message function?


        [Function("PerformBackgroundJob")]
        [SignalROutput(HubName = "progress", ConnectionStringSetting = "AzureSignalRConnectionString")]
        public SignalRMessageAction PerformBackgroundJob(
            [QueueTrigger(LibraryConstants.testQueue, Connection = "connectionstring-azure-storage")] string JobId)
        {
            var msg = new SignalRMsg();
            
            _logger.LogInformation("PerformBackgroundJob started");
            Stopwatch sw1 = new Stopwatch();
            sw1.Start();
            
            List<ProcessFileResponse> response = new List<ProcessFileResponse>();

            msg = new SignalRMsg()
            {
                UserId = JobId,
                Target = "taskStarted",
                Arguments = new object[] { "PerformBackgroundJob started" }
            };
            //Send a message here
            //SendMessage(msg);
            _logger.LogInformation("PerformBackgroundJob data reviewed");
            
            for (int i = 0; i < 100; i++)
            {
                msg = new SignalRMsg()
                {
                    UserId = JobId,
                    Target = "taskProgressChanged",
                    Arguments = new object[] { i + 1 }
                };
                //Send a message here
                //SendMessage(msg);
                Thread.Sleep(200);
            }
            sw1.Stop();
            TimeSpan ts = sw1.Elapsed;

            // Format and display the TimeSpan value.
            string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
                ts.Hours, ts.Minutes, ts.Seconds,
                ts.Milliseconds / 10);
            ProcessFileResponse outResponse = new ProcessFileResponse();
            outResponse.Errors = 0;
            outResponse.Warnings = 0;
            outResponse.Status = 1;
            outResponse.TabName = "Background action";
            outResponse.Message = $"RunTime: {elapsedTime}";
            response.Add(outResponse);
            
            _logger.LogInformation("PerformBackgroundJob completed");
            //this is The only message that is visible
            return new SignalRMessageAction("taskEnded")
            {
                Arguments = new object[] { response },
                UserId = JobId
            };
        }

I tried to use a separate function to send messages but it doesn't work, or maybe I'm calling the function in an incorrect way.

[Function(nameof(SendMessage))]
[SignalROutput(HubName = "progress", ConnectionStringSetting = "AzureSignalRConnectionString")]
public static SignalRMessageAction SendMessage(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post")] SignalRMsg req)
{
    return new SignalRMessageAction(req.Target)
    {
        Arguments = req.Arguments,
        UserId = req.UserId
    };
}

public class SignalRMsg
{
    public string UserId { get; set; }
    public string Target { get; set; }
    public object[] Arguments { get; set; }
}

Ivan Cortez · Accepted Answer · 2024-09-27 16:53:04Z

Ok so the answer to my issue was to use the QueueServiceClient. first within Program.cs I added the following to the servcie configuration:

services.AddAzureClients(builder => {
    builder.AddQueueServiceClient(azStorage).ConfigureOptions(options =>
    options.MessageEncoding = Azure.Storage.Queues.QueueMessageEncoding.Base64);
});

One important note is that the MessageEncoding option is important to send messages with azure functions. Afterwards I added a new signalR message function that is triggered with a QueueTrigger:

[Function(nameof(SendMessageQueue))]
[SignalROutput(HubName = "progress", ConnectionStringSetting = "AzureSignalRConnectionString")]
public static SignalRMessageAction SendMessageQueue(
    [QueueTrigger("messagequeue", Connection = "connectionstring-azure-storage")] string messageQueue)
{
    var message = JsonSerializer.Deserialize<SignalRMsg>(messageQueue);
    return new SignalRMessageAction(message.Target)
    {
        Arguments = message.Arguments,
        UserId = message.UserId
    };
}

For easy of use I also created a small message class to pass the UserId, Target and Arguments directly:

public class SignalRMsg
{
    public string UserId { get; set; }
    public string Target { get; set; }
    
    public object[] Arguments { get; set; }
    public SignalRMsg() { }

}

After this I changed the PerformBackgroundJob function to accommodate my changes and I was finally able to send multiple messages sending them through a queue. First by adding the queue service into the my existing class:

private readonly ILogger<BackgroundJobTest> _Logger;
private readonly QueueClient _QueueClient;
private readonly QueueServiceClient _QueueServiceClient;

public BackgroundJobTest(ILogger<BackgroundJobTest> Logger, QueueServiceClient QueueServiceClient, IServiceScopeFactory serviceProvider, ITypeCurveNeighborhoodService typeCurveNeighborhoodService)
{
    _Logger = Logger;
    _QueueClient = QueueServiceClient.GetQueueClient("messagequeue");
    _QueueServiceClient = QueueServiceClient;
}

Then I simply added and filled the new message class I created before, serialized it and then sent it as a message into the queue:

msg = new SignalRMsg()
 {
     UserId = JobId,
     Target = "taskStarted",
     Arguments = new object[] { "PerformBackgroundJob started" }
 };
 //Send a message here
 var jsonMsg = JsonSerializer.Serialize<SignalRMsg>(msg);
 await _QueueClient.SendMessageAsync(jsonMsg);
 _Logger.LogInformation("PerformBackgroundJob data reviewed");

One last part is that we must check if the queue exists in your blob storage account otherwise the messages will fail. for this I created a small function that checks and creates a queue if it doesn't exist:

private void CheckExisitngQueue(string messageQueue)
{
   var queueClient = _QueueServiceClient.GetQueueClient(LibraryConstants.messageQueue);
    queueClient.CreateIfNotExists();

}

Here is the full functions for example purposes:

[Function("PerformBackgroundJob")]
public async Task PerformBackgroundJob(
    [QueueTrigger("testQueue", Connection = "connectionstring-azure-storage")] string JobId)
{
    
    var msg = new SignalRMsg();
    
        _Logger.LogInformation("PerformBackgroundJob started");
        Stopwatch sw1 = new Stopwatch();
        sw1.Start();
        CheckExisitngQueue("messagequeue");
        List<ProcessFileResponse> response = new List<ProcessFileResponse>();

        msg = new SignalRMsg()
        {
            UserId = JobId,
            Target = "taskStarted",
            Arguments = new object[] { "PerformBackgroundJob started" }
        };
        //Send a message here
        var jsonMsg = JsonSerializer.Serialize<SignalRMsg>(msg);
        await _QueueClient.SendMessageAsync(jsonMsg);
        _Logger.LogInformation("PerformBackgroundJob data reviewed");
    
        for (int i = 0; i < 100; i++)
        {
            msg = new SignalRMsg()
            {
                UserId = JobId,
                Target = "taskProgressChanged",
                Arguments = new object[] { i + 1 } 
            };
            //Send a message here
            jsonMsg = JsonSerializer.Serialize<SignalRMsg>(msg);
            await _QueueClient.SendMessageAsync(jsonMsg);
            Thread.Sleep(200);
        }
        sw1.Stop();
        TimeSpan ts = sw1.Elapsed;

        // Format and display the TimeSpan value.
        string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
            ts.Hours, ts.Minutes, ts.Seconds,
            ts.Milliseconds / 10);
        ProcessFileResponse outResponse = new ProcessFileResponse();
        outResponse.Errors = 0;
        outResponse.Warnings = 0;
        outResponse.Status = 1;
        outResponse.TabName = "Background action";
        outResponse.Message = $"RunTime: {elapsedTime}";
        response.Add(outResponse);

        _Logger.LogInformation("PerformBackgroundJob completed");
        
         msg = new SignalRMsg()
        {
            Target = "taskEnded"
            Arguments = new object[] { response },
            UserId = JobId
        };                
        jsonMsg = JsonSerializer.Serialize<SignalRMsg>(msg);
        await _QueueClient.SendMessageAsync(jsonMsg);
}

Naveen Sharma · Accepted Answer · 2024-09-25 03:33:43Z

To send multiple messages asynchronously from a SignalR function, we use the IAsyncCollector parameter. This allows us to collect multiple SignalRMessageAction objects and send them in a batch.

You can send multiple messages in a sequential order using Azure SignalR Service like the code below:

 var message1 = new SignalRMessageAction("newMessage") { Arguments = new[] { "Message 1" } };
 var message2 = new SignalRMessageAction("newMessage") { Arguments = new[] { "Message 2" } };
    await signalRMessages.AddAsync(message1);
    await signalRMessages.AddAsync(message2);

You have to call another SignalR function from within your function to send additional messages. This can be done by invoking another HTTP-triggered function that sends the next message.

 var message1 = new SignalRMessageAction("newMessage") { Arguments = new[] { "Message 1" } };
 await signalRMessages.AddAsync(message1);
 await sendSecondMessageReq.HttpContext.Response.WriteAsync("Triggering second message function");
 return new OkResult();

I referred to this MSDOC to migrate . NET function apps. Additionally, I referred to this MSDOC for Azure SignalR Service serverless output binding.

 Stopwatch stopwatch = new Stopwatch();
        stopwatch.Start();

        for (int i = 0; i < 100; i++)
        {
            var progressMessage = new SignalRMessageAction("taskProgressChanged")
            {
                Arguments = new object[] { i + 1 },
                UserId = JobId
            };
            SendMessage(progressMessage);
            Thread.Sleep(200); 
        }

        stopwatch.Stop();
        string elapsedTime = stopwatch.Elapsed.ToString(@"hh\:mm\:ss");

        return new SignalRMessageAction("taskEnded")
        {
            Arguments = new object[] { $"Job completed in {elapsedTime}" },
            UserId = JobId
        };

Output:

enter image description here

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