Amazon Web Services – Simple Queue Service (SQS) Overview
Simple Queue Service (SQS)
SQS is Amazon’s message queuing service. It works much like IBM’s MQ Series, JMS or Oracle AQ. Pop in a message and one or more recipients can pop it out. SQS is completely open so any internet connected computer can call a web service and add or remove a message.
Because SQS is API based, you can write an interface to it in the language of your choice. There are several free Java, Ruby and PHP interfaces available (that I know of) with more coming. If your application depends on queuing, you will be able to easily plug into SQS.
An application can create as many queues as is needed and each can create an unlimited number of messages. Messages can be up to 8k in size. Internal communication is free between EC2 instances so it is usually easier (in that situation) to just send message identifier information in the message and use a different mechanism to send actual data.
SQS costs $0.01 per 10000 SQS request. That will get you 1,000,000 requests for $1.00. You also pay for data transfer though (remembering the AMI to AMI data transfer is free). Data Transfer into Amazon from the outside world is $0.10 per GB. 10GB equals $1.00.
Transfer out of Amazon is tiered (per month rates): $0.17 for first 10TB, $0.13 for the next 40TB, $0.11 for the next 100TB and $0.10 for all data over 150TB.