使用 nservicebus 延迟消息 [英] Deffering messages with nservicebus

问题描述

我正在处理 nServiceBus，我想在另一个失败时重试并发送一条消息.我听说过 Bus.Defer() 但我对它的理解有限.

I am dealing with nServiceBus and I want to retry and a message at another time when one fails. I have heard of Bus.Defer() but my understanding of it is limited.

我有一个检查股票代码的系统.它检查命令何时被调用并在晚上 8 点之后重新安排另一次检查.

I have a system that checks stock codes. It checks when the command is called and reschedules another check after 8pm.

我有 CheckCurrentProductAvailabilityCommand 运行检查股票代码的函数.这由 CurrentProductAvailabilityRequestHandler 处理.

I have CheckCurrentProductAvailabilityCommand that runs a function that checks stock codes. This is handled by CurrentProductAvailabilityRequestHandler.

如果失败，我会使用由 ScheduleCheckStockCodeAvailabilityProcessor 处理的股票代码运行 ScheduleCheckStockAvailabilityCommand.

If it fails I then run ScheduleCheckStockAvailabilityCommand with the stock code this is handled by ScheduleCheckStockCodeAvailabilityProcessor.

然后我运行一个函数 _bus.Defer(_checkStockCodeAvailability.TimeOutTime, message.StockCode);

I then run a function _bus.Defer(_checkStockCodeAvailability.TimeOutTime, message.StockCode);

我的实际代码....

if (scheduleRecheck && result.ErrorMessage.Equals("Bad Request"))
            {
                Logger.Error("Stock query for stock code '{0}' returned a 'Product Not Found' status",
                    stockcode);

                _bus.SendLocal<ScheduleCheckStockAvailabilityCommand>(cmd =>
                {
                    cmd.StockCode = stockcode;
                });
            }
        }

上面的代码工作正常.

public class ScheduleCheckStockCodeAvailabilityProcessor : IHandleMessages<ScheduleCheckStockAvailabilityCommand>
{
    readonly ICheckStockCodeAvailability _checkStockCodeAvailability;
    readonly IBus _bus;

    public ScheduleCheckStockCodeAvailabilityProcessor(ICheckStockCodeAvailability checkStockCodeAvailability, IBus bus)
    {
        _checkStockCodeAvailability = checkStockCodeAvailability;
        _bus = bus;
    }

    public void Handle(ScheduleCheckStockAvailabilityCommand message)
    {
        _bus.Defer(_checkStockCodeAvailability.TimeOutTime, message.StockCode);
    }
}

但我无法从逻辑上想到这将如何运作.

But I can't think of logically how this would work.

有什么帮助吗?

推荐答案

在你的代码中

if (scheduleRecheck && result.ErrorMessage.Equals("Bad Request"))
            {
                Logger.Error("Stock query for stock code '{0}' returned a 'Product Not Found' status",
                    stockcode);

                _bus.SendLocal<ScheduleCheckStockAvailabilityCommand>(cmd =>
                {
                    cmd.StockCode = stockcode;
                });
            }
        }

您正在发送消息 ScheduleCheckStockAvailabilityCommand.现在，在您的其他函数中，yoe 正在推迟此消息，即 ScheduleCheckStockAvailabilityCommand (我认为只有在 CheckCurrentProductAvailabilityCommand 出现错误时才会调用它).因此，根据我收集的信息，您想推迟 CheckCurrentProductAvailabilityCommand 而不是 ScheduleCheckStockAvailabilityCommand 所以我认为您的代码应该是:

you are sending a message ScheduleCheckStockAvailabilityCommand. Now in your other function yoe are deferring this message i.e. ScheduleCheckStockAvailabilityCommand (which i think is called only when there is some error with CheckCurrentProductAvailabilityCommand ). So according to what I gather you want to defer CheckCurrentProductAvailabilityCommand rather than ScheduleCheckStockAvailabilityCommand so I think your code should be:

if (scheduleRecheck && result.ErrorMessage.Equals("Bad Request"))
            {
                Logger.Error("Stock query for stock code '{0}' returned a 'Product Not               Found' status",stockcode);
              _bus.Defer(_checkStockCodeAvailability.TimeOutTime, CheckCurrentProductAvailabilityCommand);

            }
        }

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