MT3 Request-Response with asp.net mvc application

[Slava Buchkou]

Hi,

I have the following code inside asp.net mvc application

        public ActionResult Index()

        {

            var busControl = Bus.Factory.CreateUsingRabbitMq(

                c =>

                {

                    c.Host(

                        new Uri("rabbitmq://localhost/test"),

                        h =>

                        {

                            h.Username("guest");

                            h.Password("guest");

                        });

                });

            busControl.Start();

            busControl.CreateRequestClient<GetUserByEmailRequest, GetUserByEmailResponse>(

                new Uri("rabbitmq://localhost/test/user_services"),

                TimeSpan.FromSeconds(5))

                .Request(new GetUserByEmailRequest())

                .Wait();

            return View();

        }

This code works perfectly inside console application, but in asp.net application it just freezes application without any exceptions and messages.

RabbitMQ management plugin shows no new exchanges or queues and messages.

MT version: 3.0.14

.NET version 4.5

ASP.NET MVC version: 5.2.3

Thank you,

Slava

[Chris Patterson]

You should look at the example that hooks into MVC. 

https://github.com/MassTransit/Sample-ShoppingWeb

For one you should not be creating a bus in a controller action method. So take a look at the patterns in the example. 

__
Chris Patterson

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[Slava Buchkou]

Thank you for reference. Seems sample works.

But it uses Publish/Subscribe pattern instead of request/response.

I've tried to use bus.Request in the provided sample but without luck. I suppose, request should be sent and without response timeout exception thrown.

Please, help to get working sample for request/response pattern.

Thank you,

Slava

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[Chris Patterson]

There is a separate request/response sample:

https://github.com/MassTransit/Sample-RequestResponse

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[Ludovic Lebel]

Hi Chris

I'm having some hard time too figuring out how to properly make request/response call in the context of a asp.net mvc application.

The sample on github is a console application and it seems to behave differently. There is something specific to a controller's action around threading.

If you could provide a working recipe fir this that would be great.

Thanks

Ludovic  

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[Ludovic Lebel]

So, here what I've figure out :

I have this controller action :

public ActionResult GetBatchSubscriptions(int districtId)

{

     ViewData["DistrictId"] = districtId;

     var response = _myCustomersReadSideClient.GetBatchSubscriptionDescriptions(districtId);

      return PartialView("BatchSubscriptions", response.List);

}

_myCustomersReadSideClient is an object encapsulating the call to MT. Inside, it looks like that :

public BatchSubscriptionDescriptionList GetBatchSubscriptionDescriptions(int districtId)

{

BatchSubscriptionDescriptionList response = null;

response = Task.Run(() =>

{

var client = CreateRequestClient<GetBatchSubscriptionDescriptionsRequest, BatchSubscriptionDescriptionList>();

return client.Request(new GetBatchSubscriptionDescriptionsRequest(districtId));

}).Result;

return response;

}

I have try to use instead, (without the thread wrapper) and is didn't worked:

var client = CreateRequestClient<GetBatchSubscriptionDescriptionsRequest, BatchSubscriptionDescriptionList>();

return client.Request(new GetBatchSubscriptionDescriptionsRequest(districtId)).Result;

Chris, does that make sense to you?

Ludovic

[mald]

To anybody having trouble with Request/Response in MVC, please look at this sample I quickly made. Hope it helps.

https://github.com/maldworth/tutorial-masstransit-request-response

Good luck!

[Wayne Brantley]

Your issue is all around async/await.  You are encountering the classic deadlock.  If you ever use sometask.Result you have most likely messed up.  This kind of thing works find outside of asp.net as the context is not an issue.  Lots of articles about this (http://stackoverflow.com/questions/15021304/an-async-await-example-that-causes-a-deadlock) and is not specific to mass transit.

However, I know that it was not until a really recent version that ConfigureAwait(false) was put in lots of places, which is key to avoiding these deadlocks.

Make your controller action and GetBatchSubscriptionDescriptions async, then use await on that call as well as the calls in GetBatchSubscriptionDescriptions.   Your problem will go away.

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[Ludovic Lebel]

Thanks for the answer Wayne.

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[Jedidja Bourgeois]

Thanks! Came in handy today :)