How to get response via Masstransit? - rabbitmq

Question

I want to get a response (GetStatusResponse) from consumer (GetStatusConsumer).
My request is putted in Rabbit queue "getstatus" but my consumer is not rise and timeout occurs.
Publish-method and Consumer nested in one project
It seems to me trouble in the Startup.cs. Could you help me?
I have following code in Startup.cs
...
services.AddSingleton(provider =>
{
var getStatusBusOptions = provider.GetRequiredService<IOptions<BusOptions>>().Value;
var bus = Bus.Factory.CreateUsingRabbitMq(sbc =>
{
var host = sbc.Host(new Uri(getStatusBusOptions.HostUri), h =>
{
h.Username(getStatusBusOptions.UserName);
h.Password(getStatusBusOptions.Password);
});
sbc.ReceiveEndpoint("getstatus", ep =>
{
ep.Consumer<GetStatusConsumer>(provider);
ep.PrefetchCount = getStatusBusOptions.PrefetchCount;
ep.UseConcurrencyLimit(getStatusBusOptions.UseConcurrencyLimit);
});
});
return new GetStatusBus
{
Bus = bus,
HostUri = getStatusBusOptions.HostUri
};
});
...
Following code in class GetStatusPublisher.cs
public class GetStatusPublisher : IGetStatusPublisher
{
readonly GetStatusBus _bus;
public GetStatusPublisher(GetStatusBus bus)
{
_bus = bus;
}
public async Task<Tout> GetResponse<Tin, Tout>(Tin request) where Tin : class where Tout : class
{
var serviceAddress = new Uri($"rabbitmq://rabbitmq.test.com/jgt/getstatus");
var timeout = TimeSpan.FromSeconds(30);
var client = new MessageRequestClient<Tin, Tout>(_bus.Bus, serviceAddress, timeout);
var resp = await client.Request(request); // <== Timeout here and don't rise consumer (GetStatusConsumer)
return resp;
}
Here is Publish-method:
...
readonly IGetStatusPublisher _getStatusPublisher;
...
var resp = await _getStatusPublisher.GetResponse<GetStatusRequest, GetStatusResponse>(statusReq);
Consumer has following code:
public class GetStatusConsumer : MetricWriter, IConsumer<GetStatusRequest>
{
public GetStatusConsumer(IMetrics metrics) : base(metrics)
{
......
}
public async Task Consume(ConsumeContext<GetStatusRequest> context)
{
....
}
}

Answer 1

First things first, I don't think you're starting the bus. That's the major issue.
However...
Are you using an antique version of MassTransit? Your code is seriously out of date, and I'd suggest updating it to use the current version/syntax as your code example above has so many things wrong with it.
services.AddMassTransit(x =>
{
x.AddConsumer<GetStatusConsumer>();
x.UsingRabbitMq((context, cfg) =>
{
var getStatusBusOptions = context.GetRequiredService<IOptions<BusOptions>>().Value;
cfg.Host(new Uri(getStatusBusOptions.HostUri), h =>
{
h.Username(getStatusBusOptions.UserName);
h.Password(getStatusBusOptions.Password);
});
cfg.PrefetchCount = getStatusBusOptions.PrefetchCount;
cfg.ConcurrentMessageLimit = getStatusBusOptions.UseConcurrencyLimit;
cfg.ConfigureEndpoints(context);
});
});
services.AddMassTransitHostedService();
services.AddGenericRequestClient();
Then, you can simply add a dependency on IRequestClient<T> to send requests and get responses. Your updated publisher code may look like:
public class GetStatusPublisher :
IGetStatusPublisher
{
public GetStatusPublisher(IServiceProvider provider)
{
_provider = provider;
}
public async Task<Tout> GetResponse<Tin, Tout>(Tin request) where Tin : class where Tout : class
{
var client = _provider.GetRequiredService<IRequestClient<Tin>>();
var response = await client.GetResponse<Tout>(request);
return response.Message;
}
}

Answer 2

If I use following code I get error: "System.InvalidOperationException: Cannot resolve scoped service 'MassTransit.IRequestClient`1[GetStatusTry.Contracts.GetStatusRequest]' from root provider....."
public async Task<Tout> GetResponse<Tin, Tout>(Tin request) where Tin : class where Tout : class
{
try
{
var client = _provider.GetRequiredService<IRequestClient<Tin>>(); // << --- here is error
var response = await client.GetResponse<Tout>(request);
return response.Message;
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
throw;
}
}
But this code works Ok:
public class Dev2Controller : ControllerBase
{
IRequestClient<GetStatusRequest> _client;
public Dev2Controller(IGetStatusPublisher getStatusPublisher, IRequestClient<GetStatusRequest> client)
{
_client = client;
}
[HttpPost]
public async Task<GetStatusResponse> GetStatus2()
{
var req = new GetStatusRequest { Statuses = new List<int> { 1, 2, 3 }, TerminalDescr = "try to get status2" };
var response = await _client.GetResponse<GetStatusResponse>(req);
return (response.Message);
}
}

Answer 3

this code is working
public class GetStatusPublisher : IGetStatusPublisher
{
readonly IServiceProvider _provider;
public GetStatusPublisher(IServiceProvider provider)
{
_provider = provider;
}
public async Task<Tout> GetResponse<Tin, Tout>(Tin request) where Tin : class where Tout : class
{
try
{
using (var _scope = _provider.CreateScope())
{
var client = _scope.ServiceProvider.GetRequiredService<IRequestClient<Tin>>();
var response = await client.GetResponse<Tout>(request);
return response.Message;
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
throw;
}
}
}