CODEWITHSUNDEEP
ibm-mq
user1771386
user1771386

Reputation: 93

Reconnecting with MQ - issues

I'm looking forward to implement a somewhat intelligent MQ comms module, which should be tolerant for the outages in the network connection. Basically it should try to reconnect each 5 seconds if connection was lost.

The problem is the following. I use the following code for reading: 

queueMessage = new MQMessage();
               queueMessage.Format = MQC.MQFMT_STRING;
               queueGetMessageOptions = new MQGetMessageOptions();
               queueGetMessageOptions.Options = MQC.MQGMO_SYNCPOINT + MQC.MQGMO_WAIT + MQC.MQGMO_FAIL_IF_QUIESCING;
               queueGetMessageOptions.WaitInterval = 50;
               producerQueue.Get(queueMessage, queueGetMessageOptions);
               msg = queueMessage.ReadBytes(queueMessage.MessageLength);

(Of course I successfully connect to the queuemanager before etc.)
I got the following issue: when this routine runs, but at the time of .Get there's no connection, the code simply hangs and stays in the .Get. I use a timer to see if there's a timeout (in theory even that shouldn't be necessary, is that right?) and at the timeout I try to reconnect. BUT when this timeout expires, I still see that the queuemanager reports that it's connected, while its clearly not (no physical connection is present anymore). This issue has popped up since I use SYNCPOINT, and I experience the same when I cut connection during writing, or in this case I try to force a Disconnect on the queuemanager. So please help, what settings shall I use to avoid getting stuck in Get and Put and rather have an MQException thrown or something controllable? Thanks!

UPDATE: I used the following code to connect to the QueueManager.

Hashtable props = new Hashtable();
props.Add(MQC.HOST_NAME_PROPERTY, Host);
props.Add(MQC.PORT_PROPERTY, Port);
props.Add(MQC.CHANNEL_PROPERTY, ChannelInfo);
if(User!="") props.Add(MQC.USER_ID_PROPERTY, User);
if(Password!="") props.Add(MQC.PASSWORD_PROPERTY, Password);
props.Add(MQC.TRANSPORT_PROPERTY, MQC.TRANSPORT_MQSERIES_MANAGED);

queueManager = new MQQueueManager(QueueManagerName, props);
producerQueue = queueManager.AccessQueue(
ProducerQueueName,
MQC.MQOO_INPUT_AS_Q_DEF                 // open queue for input
+ MQC.MQOO_FAIL_IF_QUIESCING);   // but not if MQM stopping
consumerQueue = queueManager.AccessQueue(
ConsumerQueueName,
MQC.MQOO_OUTPUT + MQC.MQOO_BROWSE + MQC.MQOO_INPUT_AS_Q_DEF                 // open queue for output
+ MQC.MQOO_FAIL_IF_QUIESCING);   // but not if MQM stopping

Needless to say that normally the code works well. Read/Write, connect/disconnect works as it should, I only have to figure out the current issue. Thanks!

Upvotes: 0

Views: 3676

Answers (1)

Shashi
Shashi

Reputation: 15283

What version of MQ are you using? For automatic reconnection to work the queue manager need to be at least at MQ v701 and MQ .NET client needs to be a MQ v7.1 level.

Assuming you are using MQ v7.1 .NET client, you need to specify reconnect option during connection create. You will need to enable reconnection by adding something like:

props.Add(MQC.CONNECT_OPTIONS_PROPERTY, MQC.MQCNO_RECONNECT);

Reconnection can be enabled/disabled from mqclient.ini file also.

But what is surprising is why the Get/Put are hanging when there is no network connection. Hope you are not connecting a queue manager running on the same machine as your application. There is no need to set any timer or something like that. You can issue MQ calls and if there is anything wrong with connection, an exception will be thrown.

Update:

I think you are referring to IsConnected property of MQQueueManager class. The documentation says the value of this property: "If true, a connection to the queue manager has been made, and is not known to be broken. Any calls to IsConnected do not actively attempt to reach the queue manager, so it is possible that physical connectivity can break, but IsConnected can still return true. The IsConnected state is only updated when activity, for example, putting a message, getting a message, is performed on the queue manager. If false, a connection to the queue manager has not been made, or has been broken, or has been disconnected."

As you can see a True value does not mean the connection is still ON. My suggestion would be to call a method, Put/Get and handle any exception thrown.

Put/Get/Disconnect calls hanging appears to be a problem. My suggestion would be raise a PMR with IBM.

Upvotes: 2

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