Some time ago I got a question from Eto: “How would I go about this if I just want to receive one message only?” And I started thinking… is it possible in .Net Core?

I used the newest Microsoft.Azure.ServiceBus package, that is dedicated for .Net Core, but there is no method to receive only one message. So I used regular RegisterMessageHandler with a twist:

    public void ReceiveOne()
    {
        var queueClient = new QueueClient(ServiceBusConnectionString, "go_testing");

        queueClient.RegisterMessageHandler(
            async (message, token) =>
            {
                var messageBody = Encoding.UTF8.GetString(message.Body);
                Console.WriteLine($"Received: {messageBody}, time: {DateTime.Now}");
                await queueClient.CompleteAsync(message.SystemProperties.LockToken);

                await queueClient.CloseAsync();
            },
            new MessageHandlerOptions(async args => Console.WriteLine(args.Exception))
            { MaxConcurrentCalls = 1, AutoComplete = false });
    }

As you can see it is a standard approach, but after successfully processed message, I close queueClient. This works and it receives only one message, but it also gives an error.

I wasn’t fully satisfied with the solution, so I asked a question on StackOverflow: https://stackoverflow.com/questions/50438466/azure-service-bus-in-net-core-how-to-receive-only-one-message

After a few hours, I got an answer, that it is possible and I should just… use different package!

Using the old package

So far I didn’t manage to use old package in .NetCore project. So in order to install package WindowsAzure.ServiceBus, you need to have project referencing full framework.

And here is the code:

    public async Task ReceiveOne()
    {
        var queueClient = QueueClient.CreateFromConnectionString(ServiceBusConnectionString, "go_testing", ReceiveMode.PeekLock);

        var message = await queueClient.ReceiveAsync();
        Console.WriteLine($"Received: {message.GetBody<string>()}, time: {DateTime.Now}");

        await message.CompleteAsync();
    }

So that’s it and it works, but sadly not in .Net Core. However, I’ll keep this post up to date when such thing will be possible.