:Manage queues

Step 1: Prepare the environment

1. Download the latest version of MNS SDK for Python, decompress the package, and then go to the mns_python_sdk subdirectory.

2. Open the sample.cfg file, and specify an AccessKey ID, an AccessKey secret, an endpoint, and a Security Token Service (STS) token.

   • AccessKey ID and AccessKey secret

     • The AccessKey pair that is used to call API operations in Alibaba Cloud.

     • If you use an Alibaba Cloud account, go to the AccessKey Pair page of the Alibaba Cloud Management Console to create and view your AccessKey pair.

     • If you use MNS as a Resource Access Management (RAM) user, log on to the RAM console to view the AccessKey pair.

   • Endpoint

     • The endpoint that is used to access MNS. To view the endpoints, log on to the MNS console. For more information, see the "Obtain the endpoints of a queue" section of the Manage queues in the console topic.

     • The endpoints of MNS vary based on the region.

   • STS token

     • The temporary access credential that is provided by RAM. If you access Alibaba Cloud services as a RAM user or by using an Alibaba Cloud account, you do not need to specify an STS token. For more information, see What is STS?

3. Go to the sample directory in which all the sample code resides.

Step 2: Create a queue

Run the createqueue.py file to create a queue. The default name of the new queue is MySampleQueue. You can also specify another queue name. For more information, see Queue.

• Run the following command:

  python createqueue.py MyQueue1         

  The following result is returned:

  Create Queue Succeed!  QueueName:MyQueue1

• Sample code:

  The endpoint, AccessKey ID, AccessKey secret, and STS token are retrieved from the sample.cfg file that is specified in Step 1.

  my_account = Account(endpoint, accid, acckey, token)
  queue_name = sys.argv[1] if len(sys.argv) > 1 else "MySampleQueue"
  my_queue = my_account.get_queue(queue_name)
  
  queue_meta = QueueMeta()
  try:
      queue_url = my_queue.create(queue_meta)
      print "Create Queue Succeed!  QueueName:%s\n" % queue_name
  except MNSExceptionBase, e:
      if e.type == "QueueAlreadyExist":
          print "Queue already exist, please delete it before creating or use it directly."
          sys.exit(0)
      print "Create Queue Fail!  Exception:%s\n" % e

Step 3: Send messages

Run the sendmessage.py file to send multiple messages to the queue. You must specify the name of the queue that is created in Step 2 by using a specific parameter. For more information, see QueueMessage.

• Run the following command:

  python sendmessage.py MyQueue1

  The following result is returned:

  ==========Send Message To Queue==========
  QueueName:MyQueue1
  MessageCount:3
  
  Send Message Succeed!  MessageBody:I am test message 0. MessageID:3EBE662B52BC99BC-1-154BD99CCA7-200000001
  Send Message Succeed!  MessageBody:I am test message 1. MessageID:64B92941FC57837F-2-154BD99CCCE-200000001
  Send Message Succeed!  MessageBody:I am test message 2. MessageID:3EBE662B52BC99BC-1-154BD99CCF0-200000002

• Sample code:

  The endpoint, AccessKey ID, AccessKey secret, and STS token are retrieved from the sample.cfg file that is specified in Step 1.

  my_account = Account(endpoint, accid, acckey, token)
  queue_name = sys.argv[1] if len(sys.argv) > 1 else "MySampleQueue"
  my_queue = my_account.get_queue(queue_name)
  
  msg_count = 3
  
  print "%sSend Message To Queue%s\nQueueName:%s\nMessageCount:%s\n" % (10*"=", 10*"=", queue_name, msg_count)
  for i in range(msg_count):
      try:
          msg_body = "I am test message %s." % i
          msg = Message(msg_body)
          re_msg = my_queue.send_message(msg)
          print "Send Message Succeed!  MessageBody:%s MessageID:%s" % (msg_body, re_msg.message_id)
      except MNSExceptionBase, e:
          if e.type == "QueueNotExist":
              print "Queue not exist, please create queue before send message."
              sys.exit(0)
          print "Send Message Fail!  Exception:%s\n" % e      

Step 4: Receive and delete the messages

Run the recvdelmessage.py file to receive and delete all the messages from the queue. You must specify the name of the queue that is created in Step 2 by using a specific parameter. The requests to receive messages from the queue are long polling requests. If you set the WaitSeconds parameter to 3, the long-polling request times out after 3 seconds. For more information, see QueueMessage.

• Run the following command:

  python recvdelmessage.py MyQueue1                

  The following result is returned:

  ==========Receive And Delete Message From Queue==========
  QueueName:MyQueue1
  WaitSeconds:3
  
  Receive Message Succeed!  ReceiptHandle:1-ODU4OTkzNDU5My0xNDYzNDcwNDU4LTEtOA== MessageBody:I am test message 0. MessageID:3EBE662B52BC99BC-1-154BD99CCA7-200000001
  Delete Message Succeed!  ReceiptHandle:1-ODU4OTkzNDU5My0xNDYzNDcwNDU4LTEtOA==
  Receive Message Succeed!  ReceiptHandle:1-ODU4OTkzNDU5NC0xNDYzNDcwNDU4LTEtOA== MessageBody:I am test message 2. MessageID:3EBE662B52BC99BC-1-154BD99CCF0-200000002
  Delete Message Succeed!  ReceiptHandle:1-ODU4OTkzNDU5NC0xNDYzNDcwNDU4LTEtOA==
  Receive Message Succeed!  ReceiptHandle:1-ODU4OTkzNDU5My0xNDYzNDcwNDU4LTItOA== MessageBody:I am test message 1. MessageID:64B92941FC57837F-2-154BD99CCCE-200000001
  Delete Message Succeed!  ReceiptHandle:1-ODU4OTkzNDU5My0xNDYzNDcwNDU4LTItOA==
  Queue is empty!

• Sample code:

  The endpoint, AccessKey ID, AccessKey secret, and STS token are retrieved from the sample.cfg file that is specified in Step 1.

  my_account = Account(endpoint, accid, acckey, token)
  queue_name = sys.argv[1] if len(sys.argv) > 1 else "MySampleQueue"
  my_queue = my_account.get_queue(queue_name)
  
  wait_seconds = 3
  print "%sReceive And Delete Message From Queue%s\nQueueName:%s\nWaitSeconds:%s\n" % (10*"=", 10*"=", queue_name, wait_seconds)
  while True:
      try:
          recv_msg = my_queue.receive_message(wait_seconds)
          print "Receive Message Succeed!  ReceiptHandle:%s MessageBody:%s MessageID:%s" % (recv_msg.receipt_handle, recv_msg.message_body, recv_msg.message_id)
      except MNSExceptionBase,e:
          if e.type == "QueueNotExist":
              print "Queue not exist, please create queue before receive message."
              sys.exit(0)
          elif e.type == "MessageNotExist":
              print "Queue is empty!"
              sys.exit(0)
          print "Receive Message Fail!  Exception:%s\n" % e
          continue
  
      try:
          my_queue.delete_message(recv_msg.receipt_handle)
          print "Delete Message Succeed!  ReceiptHandle:%s" % recv_msg.receipt_handle
      except MNSException,e:
          print "Delete Message Fail!  Exception:%s\n" % e         

Step 5: Delete the queue

Run the deletequeue.py file to delete the queue.

• Run the following command:

  python deletequeue.py MyQueue1      

  The following result is returned:

  Delete Queue Succeed!  QueueName:MyQueue1 

• Sample code:

  The endpoint, AccessKey ID, AccessKey secret, and STS token are retrieved from the sample.cfg file that is specified in Step 1.

  my_account = Account(endpoint, accid, acckey, token)
  queue_name = sys.argv[1] if len(sys.argv) > 1 else "MySampleQueue"
  my_queue = my_account.get_queue(queue_name)
  
  try:
      my_queue.delete()
      print "Delete Queue Succeed!  QueueName:%s\n" % queue_name
  except MNSExceptionBase, e:
      print "Delete Queue Fail!  Exception:%s\n" % e