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4.8 KiB
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152 lines
4.8 KiB
ReStructuredText
.. Copyright 2010-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0
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International License (the "License"). You may not use this file except in compliance with the
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License. A copy of the License is located at http://creativecommons.org/licenses/by-nc-sa/4.0/.
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This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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either express or implied. See the License for the specific language governing permissions and
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limitations under the License.
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.. _aws-boto3-sqs-long-polling:
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###################################
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Enabling Long Polling in Amazon SQS
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###################################
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This Python example shows you how to enable long polling in Amazon SQS in one of these ways:
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* For a newly created queue
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* For an existing queue
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* Upon receipt of a message
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The Scenario
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============
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Long polling reduces the number of empty responses by allowing Amazon SQS to wait a specified time
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for a message to become available in the queue before sending a response. Also, long polling eliminates
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false empty responses by querying all of the servers instead of a sampling of servers. To enable long
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polling, you must specify a non-zero wait time for received messages. You can do this by setting the
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:code:`ReceiveMessageWaitTimeSeconds` parameter of a queue or by setting the :code:`WaitTimeSeconds`
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parameter on a message when it is received.
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In this example, Python code is used to enable long polling. The code uses the AWS SDK for Python to
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enable long polling using these methods of the AWS.SQS client class:
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* `create_queue <https://boto3.readthedocs.io/en/latest/reference/services/sqs.html#SQS.Client.create_queue>`_
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* `set_queue_attributes <https://boto3.readthedocs.io/en/latest/reference/services/sqs.html#SQS.Client.set_queue_attributes>`_.
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* `receive_message <https://boto3.readthedocs.io/en/latest/reference/services/sqs.html#SQS.Client.receive_message>`_.
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For more information about Amazon SQS long polling, see
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`Long Polling <http://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-long-polling.html>`_
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in the *Amazon Simple Queue Service Developer Guide*.
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All the example code for the Amazon Web Services (AWS) SDK for Python is available `here on GitHub <https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/python/example_code>`_.
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Prerequisite Tasks
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==================
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To set up and run this example, you must first complete these tasks:
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* Configure your AWS credentials, as described in :doc:`quickstart`.
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Enable Long Polling When Creating a Queue
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=========================================
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The example below shows how to:
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* Create a queue and enable long polling using
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`create_queue <https://boto3.readthedocs.io/en/latest/reference/services/sqs.html#SQS.Client.create_queue>`_.
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Example
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-------
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.. code-block:: python
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import boto3
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# Create SQS client
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sqs = boto3.client('sqs')
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# Create a SQS queue with long polling enabled
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response = sqs.create_queue(
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QueueName='SQS_QUEUE_NAME',
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Attributes={'ReceiveMessageWaitTimeSeconds': '20'}
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)
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print(response['QueueUrl'])
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Enable Long Polling on an Existing Queue
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========================================
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The example below shows how to:
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* Enable long polling on an existing queue using
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`set_queue_attributes <https://boto3.readthedocs.io/en/latest/reference/services/sqs.html#SQS.Client.set_queue_attributes>`_.
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Example
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-------
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.. code:: python
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import boto3
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# Create SQS client
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sqs = boto3.client('sqs')
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queue_url = 'SQS_QUEUE_URL'
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# Enable long polling on an existing SQS queue
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sqs.set_queue_attributes(
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QueueUrl=queue_url,
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Attributes={'ReceiveMessageWaitTimeSeconds': '20'}
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)
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Enable Long Polling on Message Receipt
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======================================
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Get one or more messages (up to 10), from the specified queue. Using the WaitTimeSeconds
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parameter enables long-poll support. For more information, see
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`Amazon SQS Long Polling <http://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-long-polling.html>`_
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in the *Amazon SQS Developer Guide*.
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The example below shows how to:
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* Enable a long poll for message on provided SQS queue using
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`receive_message <https://boto3.readthedocs.io/en/latest/reference/services/sqs.html#SQS.Client.receive_message>`_.
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Example
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-------
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.. code-block:: python/example_code
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import boto3
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# Create SQS client
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sqs = boto3.client('sqs')
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queue_url = 'SQS_QUEUE_URL'
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# Long poll for message on provided SQS queue
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response = sqs.receive_message(
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QueueUrl=queue_url,
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AttributeNames=[
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'SentTimestamp'
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],
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MaxNumberOfMessages=1,
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MessageAttributeNames=[
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'All'
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],
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WaitTimeSeconds=20
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)
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print(response)
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