sqs-dg-2009-02-01

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Amazon Simple Queue Service Developer GuideMessage LifecycleExtending a Message's Visibility TimeoutWhen you receive a message from the queue, you might find the visibility timeout for the queue isinsufficient to fully process and delete that message. Amazon SQS allows you to extend the visibilitytimeout for that particular message. When you extend the visibility timeout, Amazon SQS overwrites theoriginal timeout value and the new value begins at the time you changed it.For example, let's say the timeout for the queue is 30 seconds, and you receive a message. Once you're20 seconds into the timeout for that message (i.e., you have 10 seconds left), you extend it by 60 secondsby calling ChangeMessageVisibility with VisibilityTimeoutset to 60 seconds.You have then changedthe remaining visibility timeout from 10 seconds to 60 seconds.The extension you request is not stored in memory for that message. If for some reason you don't deletethe message and the message is received again, the visibility timeout for the message the next time it'sreceived is the overall value for the queue and not the extended value you previously set.Terminating a Message's Visibility TimeoutWhen you receive a message from the queue, you might find that you actually don't want to process anddelete that message. Amazon SQS allows you to terminate the visibility timeout for a specific message,which immediately makes the message visible to other components in the system to process. To do this,you call ChangeMessageVisibility with VisibilityTimeout=0 seconds.API Actions Related to Visibility TimeoutThe following table lists the API actions to use to manipulate the visibility timeout.To do this...Set the visibility timeout for a queueGet the visibility timeout for a queueSet the visibility timeout for the received messages withoutaffecting the queue's visibility timeoutExtending or terminating a message's visibility timeoutUse this actionSetQueueAttributesGetQueueAttributesReceiveMessage and set theVisibilityTimeout parameter to thevalue you wantChangeMessageVisibilityMessage LifecycleThe following diagram and process describe the lifecycle of an Amazon SQS message, called MessageA, from creation to deletion. Assume that a queue already exists.API Version 2009-02-019
Amazon Simple Queue Service Developer GuideAWS Identity and Access ManagementMessage LifecycleComponent 1 sends Message A to a queue and the message is redundantly distributedacross the SQS servers.When Component 2 is ready to process a message, it retrieves messages from the queue,and Message A is returned. While Message A is being processed, it remains in the queueand is not returned to subsequent receive requests for the duration of the visibility timeout.Component 2 deletes Message A from the queue to avoid the message being received andprocessed again once the visibility timeout expires.NoteSQS automatically deletes messages that have been in a queue for more than 4 days.AWS Identity and Access ManagementAmazon SQS integrates with AWS Identity and Access Management (IAM), a service that lets yourorganization do the following:API Version 2009-02-0110
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