RabbitMQ error when setting up Learning Transport with NServiceBus

Question

I have been using the learning transport with NServiceBus successfully whilst building a prototype.

I have then added RabbitMQ support to it which works fine.

When I switch (via app.config) back to learning transport, I get the following error even though RabbitMQ is not being configured

System.Collections.Generic.KeyNotFoundException: The given key (RabbitMQ.Routing TopologySupportsDelayedDelivery) was not present in the dictionary

My learning transport code is as follows :-

    public EndpointConfiguration ConfigureEndPoint(ILog logger, ServiceBusConfiguration config)
    {
        try
        {
            // set up server endpoint
            logger.Debug($"Creating server endpoint {config.ServerEndPointName}.");
            var endpointConfiguration = new EndpointConfiguration(config.ServerEndPointName);
            logger.Debug($"Server endpoint {config.ServerEndPointName} created.");
            logger.Debug($"Setting up persistence.");
            endpointConfiguration.UsePersistence<LearningPersistence>();
            logger.Debug($"Persistence set up.");
            logger.Debug($"Setting up transport.");
            endpointConfiguration.UseTransport<LearningTransport>();
            logger.Debug($"Transport set up.");

            endpointConfiguration.EnableInstallers();
            return endpointConfiguration;
        }
        catch (Exception ex)
        {
            logger.Error($"Could not configure service endpoint.", ex);
            throw;
        }
    }

My RabbitMQ code is

    public EndpointConfiguration ConfigureEndPoint(ILog logger, ServiceBusConfiguration config)
    {
        try
        {
            // set up server endpoint
            logger.Debug($"Creating server endpoint {config.ServerEndPointName}.");
            var endpointConfiguration = new EndpointConfiguration(config.ServerEndPointName);
            logger.Debug($"Server endpoint {config.ServerEndPointName} created.");
            logger.Debug($"Setting up transport.");
            var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
            //transport.UseConventionalRoutingTopology();
            transport.ConnectionString(config.RabbitMQConnectionString);
            logger.Debug($"Transport set up.");

            endpointConfiguration.EnableInstallers();

            logger.Debug($"Setting up persistence.");
            endpointConfiguration.UsePersistence<InMemoryPersistence>();
            logger.Debug($"Persistence set up.");
            return endpointConfiguration;
        }
        catch (Exception ex)
        {
            logger.Error($"Could not configure service endpoint.", ex);
            throw;
        }
    }

I am using NServiceBus v6.4.3 and NServiceBus.RabbitMQ v4.4.1

Any ideas?

I can't figure out why RabbitMQ is complaining when I am not even invoking it when configured for learning transport.

Yuck, why use RMQ with NSB? The former _[doesn't even have message retry](https://stackoverflow.com/a/23161921/585968)_ — , Jan 30 '18 at 10:55
Most likely, the assembly that's not referenced has remained in the bin folder, which will get scanned and picked up by NSB. The 'fix' would be to do a Clean and then build. — Hadi Eskandari, Jan 31 '18 at 07:28

score 2 · Accepted Answer · answered Jan 30 '18 at 21:28

2

Short answer: exclude RabbitMQ transport dll from scanning.

https://docs.particular.net/nservicebus/hosting/assembly-scanning

Example:

scanner.ExcludeAssemblies("NServiceBus.Transports.RabbitMQ");

Long answer: such behavior is very confusing and personally should be fixed by NServiceBus team

answered Jan 30 '18 at 21:28

alex.dev

170
11

Most likely, the assembly that's not referenced has remained in the bin folder, which will get scanned and picked up by NSB. The 'fix' would be to do a Clean and then build. – Hadi Eskandari Jan 31 '18 at 07:28
1

The trouble is that the transport can be switched via configuration so I can't remove the dll from the build. Both need to be carried. – Ace Grace Jan 31 '18 at 09:25
That gets around the problem. – Ace Grace Jan 31 '18 at 14:13
_"The trouble is that the transport can be switched via configuration so I can't remove the dll from the build"_. Mind to expand on that? Why do you need both transport to be found in the same endpoint and switch between the two using configuration? Thanks. – Sean Feldman Jan 31 '18 at 15:46

score 0 · Answer 2 · answered Jan 31 '18 at 09:25

The problem that you observe is caused by the assembly scanning of a project that references RabbitMQ but does not use it.

In any case, where a project references RabbitMQ transport without selecting it as a transport, the exclusion from scanning is the currently proposed solution.

We track it under https://github.com/Particular/NServiceBus.RabbitMQ/issues/471

RabbitMQ error when setting up Learning Transport with NServiceBus

2 Answers2