问题描述
主题客户端可以发送3个具有会话ID(例如ABCD)的消息,然后再发送4个具有会话ID(XYZ)的消息。编写订阅客户端以接收具有相关会话ID的所有7条消息非常容易。但是我只希望能够接收会话ID为XYZ的消息(并且不关心会话ID为ABCD的消息,甚至不想接收它们)。
以下示例代码可以接收具有所有会话ID的所有消息,按预期方式工作:
static async Task Main(string[] args)
{
try
{
byte[] messageBody = System.Text.Encoding.Unicode.GetBytes("Hello,world!");
ServiceBusConnectionStringBuilder builder = new ServiceBusConnectionStringBuilder(connectionString);
SubscriptionClient client = new SubscriptionClient(builder,subscriptionName,ReceiveMode.PeekLock);
var sessionHandler = new SessionHandlerOptions(ExceptionHandler);
sessionHandler.AutoComplete = true;
client.RegisterSessionHandler(SessionMessageHandler,sessionHandler);
Console.WriteLine("Press any key to exit!");
Console.ReadKey();
await client.CloseAsync();
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}
static Task SessionMessageHandler(IMessageSession session,Message message,CancellationToken cancellationToken)
{
var bodyText = System.Text.Encoding.Unicode.GetString(message.Body);
Console.WriteLine($"Session id: {message.SessionId}; Body: {bodyText}");
return Task.CompletedTask;
}
static Task ExceptionHandler(ExceptionReceivedEventArgs args)
{
var context = args.ExceptionReceivedContext;
Console.WriteLine($"Exception context: {context.Action},{context.ClientId},{context.Endpoint},{context.EntityPath}");
Console.WriteLine($"Exception: {args.Exception}");
return Task.CompletedTask;
}
问题:
解决方法
上面的代码使用的会话处理程序旨在处理多个会话,而不仅仅是一个会话。如果您只想处理具有特定ID的单个会话,则需要使用SessionClient
及其接受会话ID作为参数的AcceptMessageSessionAsync(String)
method。
使用Sean的建议,我将代码修改为following,并且可以正常工作。谢谢肖恩。
static async Task Main(string[] args)
{
try
{
Console.WriteLine("Enter session id to listen on ...");
var sessionId = Console.ReadLine();
if (sessionId == string.Empty)
{
sessionId = "12345";
}
Console.WriteLine($"Reading messages with session id: {sessionId}");
var sessionClient = new SessionClient(connectionStringWithoutEntityPath,subscriberPath,ReceiveMode.PeekLock);
var messageSession = await sessionClient.AcceptMessageSessionAsync(sessionId);
if (messageSession != null)
{
while(true)
{
Message message = await messageSession.ReceiveAsync();
if (message != null)
{
var bodyText = System.Text.Encoding.Unicode.GetString(message.Body);
Console.WriteLine($"Session id: {message.SessionId}; Body: {bodyText}");
await messageSession.CompleteAsync(message.SystemProperties.LockToken);
}
else
{
Console.WriteLine("Press Enter to keep reading. Otherwise press any other key to exit.");
if (Console.ReadLine() != string.Empty)
{
break;
}
}
}
}
await sessionClient.CloseAsync();
Console.WriteLine("Press any key to exit!");
Console.ReadKey();
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}