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From Timothy Bish <tabish...@gmail.com>
Subject Re: consumer question for NMS .Net app
Date Mon, 06 Oct 2014 13:49:56 GMT
On 10/04/2014 09:44 AM, dmc wrote:
> details:
> --------
> created c# .net 4 dll for excel using the excel RTD interface
> nms and nms.activemq dlls v 1.6.0 and 1.6.1
>
> I start my broker as:
> ApacheMQ\apache-activemq-5.10.0-bin\apache-activemq-5.10.0\bin\win64
>
> Ive taken the out of the box settings for everything.
>
> I register interest in an RTD topic from excel as:
>
>          private ISession session;
>          private bool blnUpdateNotifyCalled = false;
>          private string sServiceAddress = "activemq:tcp://mypcname:61616";
>
>
>          public object ConnectData(int topicId, ref Array Strings, ref bool
> GetNewValues)
>          {
>                  string messageSubject = Strings.GetValue(0) as string;
>
>                  String messageDestination = "topic://" + messageSubject;
>                  _subscriptions.Add(topicId, messageDestination);
>                  _destinations.Add(messageDestination, 0);
>                  _topicId = topicId;
>
>                  IDestination destination =
> SessionUtil.GetDestination(session, messageDestination);
>                  IMessageConsumer consumer =
> session.CreateConsumer(destination);
>                  consumer.Listener += new MessageListener(OnMessage);
>                  GetNewValues = true;
>
>                  //get the current value on bus
>                  ITextMessage message = consumer.Receive() as ITextMessage;
>                  return message.Text;..................
>
>            }
>                  
>          another one-time setup method creates the types at service startup:
>                 {
>                  Uri connecturi = new Uri(sServiceAddress);
>                  IConnectionFactory factory = new
> NMSConnectionFactory(connecturi);
>                  IConnection connection = factory.CreateConnection();
>                  session = connection.CreateSession();
>                  connection.Start();
>                 }
>
>         this is how i send a topic to the bus:
>
>                  IDestination destination =
> SessionUtil.GetDestination(session, "topic://" + topic + "~" + sField);
>                  using ( IMessageProducer producer =
> session.CreateProducer(destination) )
>                  {
>                      
>                      ITextMessage request =
> session.CreateTextMessage(messageToPost);
>                      request.NMSCorrelationID = Guid.NewGuid().ToString();
>                      request.Properties["NMSXGroupID"] = "xyz";
>                      request.Properties["myHeader"] = "xyzpubsub";
>                      producer.Send(request);
>
>
> =============================================
>
>
> This all works perfectly well EXCEPT for when a topic with a value is
> already on the bus and the ConnectData gets called and does not return any
> value.
> this is the error line : ITextMessage message = consumer.Receive() as
> ITextMessage;
> error =
> "Apache.NMS.NMSException: Cannot set Async listeners on Consumers with a
> prefetch limit of zero\r\n   at
> Apache.NMS.ActiveMQ.MessageConsumer.CheckMessageListener() in
> c:\\dev\\NMS.ActiveMQ\\src\\main\\csharp\\MessageConsumer.cs:line 1569\r\n
> at Apache.NMS.ActiveMQ.MessageConsumer.Receive() in
> c:\\dev\\NMS.ActiveMQ\\src\\main\\csharp\\MessageConsumer.cs:line 336\r\n
> at RTDServers.RTDDataServer.ConnectData(Int32 topicId, Array& Strings,
> Boolean& GetNewValues) in C:\\PubSubAddin\\PubSubAddin\\Subscribe.cs:line
> 160"
>
> But when i change the value of the topic and the listener fires - the result
> is returned.
>
> Question:
> How can i get the ConnectData to have a consumer object have a listener and
> also return the value on the bus if one currently exisits?
>
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> --
> View this message in context: http://activemq.2283324.n4.nabble.com/consumer-question-for-NMS-Net-app-tp4686144.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>
A topic consumer would only receive a message sent to the topic after it 
subscribed, unless it was a durable topic subscription which had been 
previously subscribed.

-- 
Tim Bish
Sr Software Engineer | RedHat Inc.
tim.bish@redhat.com | www.redhat.com
skype: tabish121 | twitter: @tabish121
blog: http://timbish.blogspot.com/


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