Question

我正在尝试使用NServiceBus和RabbitMQ发出多个连续请求。这是我的代码

class Program
    {
        static void Main(string[] args)
        {
            MainAsync().GetAwaiter().GetResult();
        }
        static async Task MainAsync()
        {
            ConfigureLog();

            var ec = new EndpointConfiguration("NServiceBus.RequestResponse");
            ec.UsePersistence<InMemoryPersistence>();
            ec.EnableInstallers();
            ec.EnableCallbacks();
            ec.MakeInstanceUniquelyAddressable(Guid.NewGuid().ToString());
            ec.LimitMessageProcessingConcurrencyTo(1);

            var transport = ec.UseTransport<RabbitMQTransport>();
            transport.UseConventionalRoutingTopology();
            transport.ConnectionString("host=localhost;username=guest;password=guest");
            transport.PrefetchCount(100);

            var endpoint = await Endpoint.Start(ec)
                .ConfigureAwait(false);

            try
            {
                var options = new SendOptions();
                options.SetDestination("NServiceBus.RequestResponse");

                Log($"Sending message: 1");
                var response1 = await endpoint.Request<MyResponse>(new MyMessage() { Text = "Hello World!!" }, options);
                Log($"Response 1 : {response1.Text}");

                Log($"Sending message: 2");
                var response2 = await endpoint.Request<MyResponse>(new MyMessage() { Text = "Hello from second request!!" }, options);
                Log($"Response 1 : {response2.Text}");

            }
            catch (Exception e)
            {
                Log("####  ERROR  ####");
                Log(e.Message);
                Log(e.StackTrace);
            }
            finally
            {
                await endpoint.Stop()
                    .ConfigureAwait(false);
            }

            Console.WriteLine("Press any key to exit");
            Console.ReadKey();
        }

        private static void Log(string msg)
        {
            LogManager.GetLogger("NServiceBus.RequestResponse").Debug(msg);
            Console.WriteLine(msg);
        }

        private static void ConfigureLog()
        {
            var layout = new PatternLayout
            {
                ConversionPattern = "%d [%t] %-5p %c [%x] - %m%n"
            };
            layout.ActivateOptions();
            var consoleAppender = new ConsoleAppender
            {
                Threshold = Level.All,
                Layout = layout
            };
            consoleAppender.ActivateOptions();

            var fileAppender = new FileAppender()
            {
                Threshold = Level.All,
                Layout = layout,
                File = "nsb_log.txt"
            };
            fileAppender.ActivateOptions();

            var executingAssembly = Assembly.GetExecutingAssembly();
            var repository = log4net.LogManager.GetRepository(executingAssembly);
            BasicConfigurator.Configure(repository, consoleAppender, fileAppender);

            LogManager.Use<Log4NetFactory>();
        }
    }

    public class MyMessage : IMessage
    {
        public string Text { get; set; }
    }

    public class MyMessageHandler : IHandleMessages<MyMessage>
    {
        public async Task Handle(MyMessage message, IMessageHandlerContext context)
        {
            await Console.Out.WriteLineAsync($"Message [{context.MessageId}] received: {message.Text} ");
            await context.Reply(new MyResponse() { Text = "Hi There!!" });
        }
    }

    public class MyResponse : IMessage
    {
        public string Text { get; set; }
    }

运行程序时，第二次请求尝试时出现以下异常：

2019-02-25 11:03:22,800 [9] DEBUG NServiceBus.RequestResponse [(null)] - Already specified reply routing option for this message: RouteReplyToThisInstance
2019-02-25 11:03:22,811 [9] DEBUG NServiceBus.RequestResponse [(null)] -    at NServiceBus.ApplyReplyToAddressBehavior.State.set_Option(RouteOption value)
   at NServiceBus.RoutingOptionExtensions.RouteReplyToThisInstance(SendOptions options)
   at NServiceBus.RequestResponseExtensions.<Request>d__3`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at NServiceBus.RequestResponse.Program.<MainAsync>d__1.MoveNext() in C:\Users\cruzedu\source\repos\NServiceBus.RequestResponse\NServiceBus.RequestResponse\Program.cs:line 47

我知道我可以更改代码以调用Send方法并具有响应处理程序，但是我仍然不明白为什么它不适用于请求。我需要做什么才能使其正常工作？

我尝试设置消息ID，未在第二个呼叫中传递发送选项，等等。似乎没有任何反应。我认为这可能是一个错误。

我创建了一个示例项目来重现此行为，并在GitHub上进行了共享。这是link。重要的是指出它需要RabbitMQ实例。就我而言，我使用默认的来宾用户/密码在本地（http://localhost:15672）上进行了设置。

Answer 1

每次发送消息时，您都需要初始化一个新的SendOptions副本，因为您无法重复使用以前的副本。

var options = new SendOptions();
options.SetDestination("NServiceBus.RequestResponse");
var response1 = await endpoint.Request<MyResponse>(new MyMessage() { Text = "Hello World!!" }, options);

options = new SendOptions();
options.SetDestination("NServiceBus.RequestResponse");
var response2 = await endpoint.Request<MyResponse>(new MyMessage() { Text = "Hello from second request!!" }, options);

NServiceBus 7-如何发送多个连续请求？

1 个答案: