问题描述
尝试实现Azure队列中的消息的使用者/接收者。我正在使用工作人员服务/后台服务项目 .Net core 3.1 。
以下是Program.cs
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureServices((hostContext,services) =>
{
services.AddSingleton<IQueueClient>(x => new QueueClient(hostContext.Configuration.GetConnectionString("ServiceBusConnectionString") ?? hostContext.Configuration["ServiceBusConnectionString"],hostContext.Configuration.GetValue<string>("QueueName")));
services.AddHostedService<WorkerService>();
});
以下是工作人员服务。cs
public class WorkerService : BackgroundService
{
private readonly IQueueClient queueClient;
private readonly ILogger<PolCommunicationRequestQueueServiceBusSubscriber> logger;
public WorkerService(IQueueClient queueClient,ILogger<WorkerService> logger)
{
this.queueClient = queueClient;
this.logger = logger;
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
try
{
queueClient.RegisterMessageHandler(ProcessMessagesAsync,new MessageHandlerOptions(ExceptionReceivedHandler)
{
MaxConcurrentCalls = 1,AutoComplete = false
});
}
catch (Exception ex)
{
logger.LogError(ex.Message);
}
finally
{
await queueClient.CloseAsync();
}
}
public async Task ProcessMessagesAsync(Message message,CancellationToken token)
{
// Process the message
logger.Loginformation($"Received message: SequenceNumber:{message.SystemProperties.SequenceNumber} Body:{Encoding.UTF8.GetString(message.Body)}");
await queueClient.CompleteAsync(message.SystemProperties.LockToken);
}
public Task ExceptionReceivedHandler(ExceptionReceivedEventArgs exceptionReceivedEventArgs)
{
logger.LogError($"Message handler encountered an exception {exceptionReceivedEventArgs.Exception}.");
return Task.CompletedTask;
}
}
}
但是该方法的一种变体可以工作,但会引发错误“ 消息处理程序已经注册。”
while (!stoppingToken.IsCancellationRequested)
{
queueClient.RegisterMessageHandler((Message message,CancellationToken cancellationToken) =>
{
logger.Loginformation($"Received message: SequenceNumber:{message.SystemProperties.SequenceNumber} Body:{Encoding.UTF8.GetString(message.Body)}");
//Implement DB/other logic here
return queueClient.CompleteAsync(message.SystemProperties.LockToken);
},new MessageHandlerOptions(ExceptionReceivedHandler)
{
MaxConcurrentCalls = 1,AutoComplete = false
});
logger.Loginformation("Worker running at: {time}",DateTimeOffset.Now);
await Task.Delay(1000,stoppingToken);
}
当我在控制台项目中实现它时,它可以工作。 不知道这里缺少什么。
解决方法
您应使用StartAsync
中的StopAsync
和BackgroundService
。
StartAsync
注册消息处理程序。 StopAsync
关闭queueClient
。
否则,您将注册消息处理程序并立即将其关闭,从而终止与代理的连接。
使用“有效”的变体,您会遇到一个紧密循环,因此不会关闭客户端。但是您多次注册同一消息处理程序,这是错误的。