![]() SQS: Jobs framework: The Jobs are submitted to SQS and the consumers at the other end can process the jobs asynchronously.SNS: The consumers might process the messages in different ways.SQS: All the consumers are typically identical and hence process the messages in the exact same way (each message is processed once by one consumer, though in rare cases messages may be resent).If no consumers are available then the message is lost after a few retries. Whichever consumer is present at the time of message arrival gets the message and the message is deleted. SQS: Messages are persisted for some (configurable) duration if no consumer is available (maximum two weeks), so the consumer does not have to be up when messages are added to queue.SNS: Fanout - Processing the same message in multiple ways.SQS: Decoupling two applications and allowing parallel asynchronous processing.SNS: Push Mechanism - SNS Pushes messages to consumers.SQS: Pull Mechanism - Consumers poll and pull messages from SQS.You could use SNS and send this data to multiple subscribers, each replicating the messages it receives to different storage systems ( S3, hard disk on your host, database, etc.). For example, let’s say you want to replicate data generated by an application to several storage systems. SNS distributes several copies of messages to several subscribers. Messages can be stored in SQS for a short duration of time (maximum 14 days). SQS is mainly used to decouple applications or integrate applications. If you configure SNS to send messages to an HTTP end point or email or SMS, several failures to send message may result in messages being dropped. It allows clients to be offline, tolerant to network and host failures. By coupling SNS with SQS, you can receive messages at your pace. Email and SMS maybe not your choice of processing messages quickly. ![]() Your end point may just die because of heavy volume of messages. You may not want an external service to make connections to your hosts (a firewall may block all incoming connections to your host from outside). There are advantages to coupling SNS with SQS. You can have SNS send messages to email, SMS or HTTP end point apart from SQS. You don't have to couple SNS and SQS always. If you want unknown number and type of subscribers to receive messages, you need SNS. SNS supports several end points such as email, SMS, HTTP end point and SQS. Polling inherently introduces some latency in message delivery in SQS unlike SNS where messages are immediately pushed to subscribers. Other receivers do not receive the same message later. Any one receiver can receive a message, process and delete it. Messages can't be received by multiple receivers at the same time. Receivers have to poll or pull messages from SQS. Messages are pushed to subscribers as and when they are sent by publishers to SNS. Why does not AWS allow subscribing standard SQS to FIFO SNS, as it seems to be simply relaxing the ordering requirement after the messages arrive in SQS?Īre there any workarounds? I see a few suggestions of using lambda to receive messages from SNS and send them to SQS but that means additional costs for lambda execution.SNS is a distributed publish-subscribe system. However, AWS seems to allow subscribing only So the SNS topic was created as FIFO and the order-sensitive subscribers use FIFO SQS.įor the other subscribers, the order does not matter and duplication is acceptable, so those would prefer to use standard SQS to avoid the higher FIFO queue prices and other restrictions. In our system, an SNS topic has several subscribers, each one of them doing different processing on the messages.įor some of the subscribers, the order in which the original events occurred and as they were received through the SNS is significant.
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