MQSeries.net :: View topic - Issue w/ concurrent get calls using java class and web ser

ora · Posted: Sat Sep 30, 2006 5:29 am Post subject:

Hello,

I have a java class that i used to create a web service. I have one function (putMsgOnRequestQueue) that puts a message on to a request queue and another function that gets message off of a response queue. When I run my script with java (main), I know that I can put and get a successful response. Even when I run a test using a java Client that calls web service, I can put and get a successful response. The issue is when I do multiple calls to web service at a time. Example: 5 concurrent calls. I might get back the first couple of responses then I get null pointer exception (Error 2033 - NO MSG ON QUEUE). When I close queues and disconnect from queue manager, message is on response queue. I have looked into adjusting my wait interval and this problem still occurs. I can see all of my requests on the request queue, so putting message on request queue doesn't seem to be a problem. It is when I attempt to get a message from the response queue. I am not certain of this but, issue seems to be related to using a priority of some sort when responding to request.

FYI: MQ is a clients remote MQ (CICS). Client uses a trigger on the request queue. When I put a message on request queue, a trigger is set so that a reply is put on the response queue.

Java put and get functions below:

/**

* This method puts a message on the Request Queue and returns the correlation

* id.

*

* @param inMsg the message to send.

* @return String the correlation id.

* @exception Exception thrown if an error occurred sending/receiving the message.

*

*/

public String putMsgOnRequestQueue(ina.mq.connector.BaseConnector connect, String inMsg) throws Exception

{

try

{

// Connect to MQ

makeMQConnection( connect );

// Create MQ Message

MQMessage myRequestMsg = new MQMessage();

// create message options

MQPutMessageOptions pmo = new MQPutMessageOptions();

// accept defaults

pmo.options = MQC.MQPMO_NONE;

// Clear the message

myRequestMsg.clearMessage();

// Get next correlation id

getNextCorrelationId();

// Set correlation id

myRequestMsg.correlationId = mqCorrelationId.getBytes();

// Set message id

myRequestMsg.messageId = mqCorrelationId.getBytes();

// Set message format

myRequestMsg.format = MQC.MQFMT_STRING;

// Write the message

myRequestMsg.writeString(inMsg);

// Put message on the queue

mqRequestQueue.put(myRequestMsg, pmo);

finalise();

}

catch (MQException ex)

{

System.out.println("MQ exception occurred : Completion code "

+ ex.completionCode

+ " Reason code "

+ ex.reasonCode);

log.fatal("MQ exception occurred : Completion code "

+ ex.completionCode

+ " Reason code "

+ ex.reasonCode);

//Close all connections

finalise();

// Throw exception

throw ex;

}

catch (java.io.IOException ex)

{

System.out.println("An error occurred reading from message buffer: " + ex);

log.fatal("An error occurred reading from message buffer: " +ex);

//Close all connections

finalise();

// Throw exception

throw ex;

}

// Return correlation id

return mqCorrelationId;

}

/**

* This method retrieves a message from the Response Queue based on the correlation

* id. If the correlation id is null then the next message on the queue is

* retrieved.

*

* @param inCorrelationId the correlation id of the message to retrieve or null

* to retrieve the next message.

* @param inWaitInterval the amount of time in milliseconds to wait for a message. 0 indicates

* no wait time.

*

* @return String the retrieved message

* @exception Exception thrown if an error occurred retrieving the message.

*

*/

public String getMsgFromResponseQueue(ina.mq.connector.BaseConnector connect, String inCorrelationId, int inWaitInterval) throws Exception

{

try{

// Connect to MQ

makeMQConnection( connect );

// Create response MQ Message

MQMessage myResponseMessage = new MQMessage();

// Set get options

MQGetMessageOptions myGetMessageOptions = new MQGetMessageOptions();

myGetMessageOptions.options = MQC.MQGMO_WAIT + MQC.MQGMO_FAIL_IF_QUIESCING + MQC.MQGMO_CONVERT;

// If correlation id supplied then match on it

if( inCorrelationId != null && inCorrelationId.length() > 0)

{

myGetMessageOptions.matchOptions = myGetMessageOptions.matchOptions | MQC.MQMO_MATCH_CORREL_ID;

myResponseMessage.correlationId = inCorrelationId.getBytes();

}

// Set to none

else

{

myResponseMessage.correlationId = MQC.MQCI_NONE;

}

// Set message id to none

myResponseMessage.messageId = MQC.MQCI_NONE;

// Wait time provided

if( inWaitInterval > 0)

{

// Set wait if wait option if wait time provided

myGetMessageOptions.waitInterval = inWaitInterval;

}

// Actually pull the message(s) from the MQ

mqResponseQueue.get(myResponseMessage, myGetMessageOptions);

// Read message

int dataLength = myResponseMessage.getMessageLength();

byte[] buffer = new byte[dataLength];

myResponseMessage.readFully(buffer);

String myData = new String(buffer);

finalise();

// Return message

return myData;

}catch (MQException ex)

{

System.out.println("MQ exception occurred : Completion code "

+ ex.completionCode

+ " Reason code "

+ ex.reasonCode);

log.fatal("MQ exception occurred : Completion code "

+ ex.completionCode

+ " Reason code "

+ ex.reasonCode);

//Close all connections

finalise();

// Throw exception

throw ex;

}

catch (java.io.IOException ex)

{

System.out.println("An error occurred reading from message buffer: " + ex);

log.fatal("An error occurred reading from message buffer: " +ex);

//Close all connections

finalise();

// Throw exception

throw ex;

}

}