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<p class="MsoNormal">Hi,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I am trying to dequeue data from the RabbitMQ. Why is it so that the data is not dequeued in the same order in which it was enqueued into the queue?</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I see that the data is dequeued in a random order. Is it an expected behavior?</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Following is the block of code that I am using to dequeue:</p>
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<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> </span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>public</b> <b>int</b> init(String hostName, <b>int</b> port, String userName, String password, String queueName)
<b>throws</b> OceRecoverableException</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>if</b>(<b>true</b> == <i>LOG</i>.isDebugEnabled()) {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<i>LOG</i>.debug("Executing RabbitMqConsumer::init");</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>try</b> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>super</b>.initialize(hostName, port, userName, password, queueName);</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }
<b>catch</b> (IOException ioe) {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> String message = "RabbitMQ consumer failed to create connection with the RabbitMQ server.";</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<i>LOG</i>.error( message + " [ERROR: " + ioe.getMessage() + "]");</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>throw</b> <b>new</b> OceRecoverableException(ioe); </span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
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</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>this</b>.queueingConsumer = <b>new</b> QueueingConsumer(<b>this</b>.channel); <b>
<span style="color:red">//channel is the member of parent class</span></b></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
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<b>try</b> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>this</b>.channel.basicConsume(queueName, <b>false</b>, <b>this</b>.queueingConsumer);</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }
<b>catch</b>(IOException ioe) {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> String message = "RabbitMQ consumer failed to set the QueueingConsumer callback for consuming data.";</span></p>
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<i>LOG</i>.error( message + " [ERROR: " + ioe.getMessage() + "]");</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>throw</b> <b>new</b> OceRecoverableException(ioe); </span>
</p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>return</b> 0;</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> </span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>public</b> <b>byte</b>[] fetchMessage(<b>int</b> timeout) <b>throws</b> OceRecoverableException</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<i>LOG</i>.debug("RabbitMqConsumer::fetchMessage"); </span></p>
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</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>if</b>(<b>this</b>.channel == <b>null</b>)</span></p>
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<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>throw</b> <b>new</b> OceRecoverableException("The channel is not initialized; Initilize the channel by calling init method");
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> QueueingConsumer.Delivery delivery;</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>try</b> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> delivery =
<b>this</b>.queueingConsumer.nextDelivery(timeout);</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }
<b>catch</b>(Exception ex) {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> String message = "Error occurred while fetching data from the RabbitMQ server.";</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<i>LOG</i>.error( message + " [ERROR: " + ex.getMessage() + "]");</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>throw</b> <b>new</b> OceRecoverableException(ex);</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>if</b>(delivery != <b>null</b>)</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>try</b> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>this</b>.channel.basicAck(delivery.getEnvelope().getDeliveryTag(), <b>false</b>);</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }
<b>catch</b> (IOException ioe) {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> String message = "Error occurred while sending acknowledgement to the RabbitMQ server for the fetched message.";</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<i>LOG</i>.error( message + " [ERROR: " + ioe.getMessage() + "]");</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>throw</b> <b>new</b> OceRecoverableException(ioe);</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>byte</b>[] body = delivery.getBody();</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>return</b> body;</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>else</b></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> {</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">
<b>return</b> <b>null</b>;</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> }</span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New""> </span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt; font-family:"Courier New"">}</span></p>
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<p class="MsoNormal"> </p>
<p class="MsoNormal">It would be great, if someone could guide me regarding this? I want the data to be fetched in the order it was enqueued.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Thanks & Regards,</p>
<p class="MsoNormal">Kamal</p>
</div>
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