Message received callback in desktop applications

[pgarbo]

Hi,

Is there a way to subscribe to an incoming message in a similar way as .AddConsumer from DependencyInjection lib does with a callback, but in a non-ASP.Net app? This is for desktop clients written in .Net Framework as well as in .Net Core for WPF.

Pawel

[Havret]

Hi @pgarbo,

There is nothing built-in unfortunately, but you should be able to use DependencyInjection extensions package even in desktop/console apps. You just need to include Microsoft.Extensions.DependencyInjection so you have access to ServiceCollection and ServiceProvider types.

class Program
{
    static async Task Main()
    {
        var endpoint = Endpoint.Create("localhost", 5672, "guest", "guest");
        var serviceCollection = new ServiceCollection();
        var activeMqBuilder = serviceCollection.AddActiveMq("my-broker", new[] { endpoint });
        activeMqBuilder.AddConsumer("my-address", RoutingType.Multicast, async (message, consumer, serviceProvider, cancellationToken) =>
        {
            // process your message here
            // just remember to use Dispatcher.Invoke https://learn.microsoft.com/en-us/dotnet/api/system.windows.threading.dispatcher.invoke?view=windowsdesktop-7.0
            // if you want to update your UI bits 
            await consumer.AcceptAsync(message).ConfigureAwait(false);
        });
        
        // build service provider
        await using var serviceProvider = serviceCollection.BuildServiceProvider();
        
        // and resolve IActiveMqClient to be able to start and stop ArtemisNetClient
        var activeMqClient = serviceProvider.GetRequiredService<IActiveMqClient>();
            
        // call this as part of your app boot logic
        await activeMqClient.StartAsync(CancellationToken.None);

        // call this as part of your app shutdown logic
        await activeMqClient.StopAsync(CancellationToken.None);
    }
}

If for whatever reason, that's not an option, writing the subscribe logic shouldn't be too difficult. There are just a few special cases that should be handled. You can use ActiveMqConsumer.cs as a starting point and adjust the code to best suit your needs.

Best,
Havret