Tag Archives: Amazon Simple Notification Service

New – SES Dedicated IP Pools

Post Syndicated from Randall Hunt original https://aws.amazon.com/blogs/aws/new-ses-dedicated-ip-pools/

Today we released Dedicated IP Pools for Amazon Simple Email Service (SES). With dedicated IP pools, you can specify which dedicated IP addresses to use for sending different types of email. Dedicated IP pools let you use your SES for different tasks. For instance, you can send transactional emails from one set of IPs and you can send marketing emails from another set of IPs.

If you’re not familiar with Amazon SES these concepts may not make much sense. We haven’t had the chance to cover SES on this blog since 2016, which is a shame, so I want to take a few steps back and talk about the service as a whole and some of the enhancements the team has made over the past year. If you just want the details on this new feature I strongly recommend reading the Amazon Simple Email Service Blog.

What is SES?

So, what is SES? If you’re a customer of Amazon.com you know that we send a lot of emails. Bought something? You get an email. Order shipped? You get an email. Over time, as both email volumes and types increased Amazon.com needed to build an email platform that was flexible, scalable, reliable, and cost-effective. SES is the result of years of Amazon’s own work in dealing with email and maximizing deliverability.

In short: SES gives you the ability to send and receive many types of email with the monitoring and tools to ensure high deliverability.

Sending an email is easy; one simple API call:

import boto3
ses = boto3.client('ses')
    Source='[email protected]',
    Destination={'ToAddresses': ['[email protected]']},
        'Subject': {'Data': 'Hello, World!'},
        'Body': {'Text': {'Data': 'Hello, World!'}}

Receiving and reacting to emails is easy too. You can set up rulesets that forward received emails to Amazon Simple Storage Service (S3), Amazon Simple Notification Service (SNS), or AWS Lambda – you could even trigger a Amazon Lex bot through Lambda to communicate with your customers over email. SES is a powerful tool for building applications. The image below shows just a fraction of the capabilities:

Deliverability 101

Deliverability is the percentage of your emails that arrive in your recipients’ inboxes. Maintaining deliverability is a shared responsibility between AWS and the customer. AWS takes the fight against spam very seriously and works hard to make sure services aren’t abused. To learn more about deliverability I recommend the deliverability docs. For now, understand that deliverability is an important aspect of email campaigns and SES has many tools that enable a customer to manage their deliverability.

Dedicated IPs and Dedicated IP pools

When you’re starting out with SES your emails are sent through a shared IP. That IP is responsible for sending mail on behalf of many customers and AWS works to maintain appropriate volume and deliverability on each of those IPs. However, when you reach a sufficient volume shared IPs may not be the right solution.

By creating a dedicated IP you’re able to fully control the reputations of those IPs. This makes it vastly easier to troubleshoot any deliverability or reputation issues. It’s also useful for many email certification programs which require a dedicated IP as a commitment to maintaining your email reputation. Using the shared IPs of the Amazon SES service is still the right move for many customers but if you have sustained daily sending volume greater than hundreds of thousands of emails per day you might want to consider a dedicated IP. One caveat to be aware of: if you’re not sending a sufficient volume of email with a consistent pattern a dedicated IP can actually hurt your reputation. Dedicated IPs are $24.95 per address per month at the time of this writing – but you can find out more at the pricing page.

Before you can use a Dedicated IP you need to “warm” it. You do this by gradually increasing the volume of emails you send through a new address. Each IP needs time to build a positive reputation. In March of this year SES released the ability to automatically warm your IPs over the course of 45 days. This feature is on by default for all new dedicated IPs.

Customers who send high volumes of email will typically have multiple dedicated IPs. Today the SES team released dedicated IP pools to make managing those IPs easier. Now when you send email you can specify a configuration set which will route your email to an IP in a pool based on the pool’s association with that configuration set.

One of the other major benefits of this feature is that it allows customers who previously split their email sending across several AWS accounts (to manage their reputation for different types of email) to consolidate into a single account.

You can read the documentation and blog for more info.

New – AWS SAM Local (Beta) – Build and Test Serverless Applications Locally

Post Syndicated from Randall Hunt original https://aws.amazon.com/blogs/aws/new-aws-sam-local-beta-build-and-test-serverless-applications-locally/

Today we’re releasing a beta of a new tool, SAM Local, that makes it easy to build and test your serverless applications locally. In this post we’ll use SAM local to build, debug, and deploy a quick application that allows us to vote on tabs or spaces by curling an endpoint. AWS introduced Serverless Application Model (SAM) last year to make it easier for developers to deploy serverless applications. If you’re not already familiar with SAM my colleague Orr wrote a great post on how to use SAM that you can read in about 5 minutes. At it’s core, SAM is a powerful open source specification built on AWS CloudFormation that makes it easy to keep your serverless infrastructure as code – and they have the cutest mascot.

SAM Local takes all the good parts of SAM and brings them to your local machine.

There are a couple of ways to install SAM Local but the easiest is through NPM. A quick npm install -g aws-sam-local should get us going but if you want the latest version you can always install straight from the source: go get github.com/awslabs/aws-sam-local (this will create a binary named aws-sam-local, not sam).

I like to vote on things so let’s write a quick SAM application to vote on Spaces versus Tabs. We’ll use a very simple, but powerful, architecture of API Gateway fronting a Lambda function and we’ll store our results in DynamoDB. In the end a user should be able to curl our API curl https://SOMEURL/ -d '{"vote": "spaces"}' and get back the number of votes.

Let’s start by writing a simple SAM template.yaml:

AWSTemplateFormatVersion : '2010-09-09'
Transform: AWS::Serverless-2016-10-31
    Type: "AWS::Serverless::SimpleTable"
    Type: "AWS::Serverless::Function"
      Runtime: python3.6
      Handler: lambda_function.lambda_handler
      Policies: AmazonDynamoDBFullAccess
          TABLE_NAME: !Ref VotesTable
          Type: Api
            Path: /
            Method: post

So we create a [dynamo_i] table that we expose to our Lambda function through an environment variable called TABLE_NAME.

To test that this template is valid I’ll go ahead and call sam validate to make sure I haven’t fat-fingered anything. It returns Valid! so let’s go ahead and get to work on our Lambda function.

import os
import os
import json
import boto3
votes_table = boto3.resource('dynamodb').Table(os.getenv('TABLE_NAME'))

def lambda_handler(event, context):
    if event['httpMethod'] == 'GET':
        resp = votes_table.scan()
        return {'body': json.dumps({item['id']: int(item['votes']) for item in resp['Items']})}
    elif event['httpMethod'] == 'POST':
            body = json.loads(event['body'])
            return {'statusCode': 400, 'body': 'malformed json input'}
        if 'vote' not in body:
            return {'statusCode': 400, 'body': 'missing vote in request body'}
        if body['vote'] not in ['spaces', 'tabs']:
            return {'statusCode': 400, 'body': 'vote value must be "spaces" or "tabs"'}

        resp = votes_table.update_item(
            Key={'id': body['vote']},
            UpdateExpression='ADD votes :incr',
            ExpressionAttributeValues={':incr': 1},
        return {'body': "{} now has {} votes".format(body['vote'], resp['Attributes']['votes'])}

So let’s test this locally. I’ll need to create a real DynamoDB database to talk to and I’ll need to provide the name of that database through the enviornment variable TABLE_NAME. I could do that with an env.json file or I can just pass it on the command line. First, I can call:
$ echo '{"httpMethod": "POST", "body": "{\"vote\": \"spaces\"}"}' |\
TABLE_NAME="vote-spaces-tabs" sam local invoke "VoteSpacesTabs"

to test the Lambda – it returns the number of votes for spaces so theoritically everything is working. Typing all of that out is a pain so I could generate a sample event with sam local generate-event api and pass that in to the local invocation. Far easier than all of that is just running our API locally. Let’s do that: sam local start-api. Now I can curl my local endpoints to test everything out.
I’ll run the command: $ curl -d '{"vote": "tabs"}' and it returns: “tabs now has 12 votes”. Now, of course I did not write this function perfectly on my first try. I edited and saved several times. One of the benefits of hot-reloading is that as I change the function I don’t have to do any additional work to test the new function. This makes iterative development vastly easier.

Let’s say we don’t want to deal with accessing a real DynamoDB database over the network though. What are our options? Well we can download DynamoDB Local and launch it with java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -sharedDb. Then we can have our Lambda function use the AWS_SAM_LOCAL environment variable to make some decisions about how to behave. Let’s modify our function a bit:

import os
import json
import boto3
if os.getenv("AWS_SAM_LOCAL"):
    votes_table = boto3.resource(
    votes_table = boto3.resource('dynamodb').Table(os.getenv('TABLE_NAME'))

Now we’re using a local endpoint to connect to our local database which makes working without wifi a little easier.

SAM local even supports interactive debugging! In Java and Node.js I can just pass the -d flag and a port to immediately enable the debugger. For Python I could use a library like import epdb; epdb.serve() and connect that way. Then we can call sam local invoke -d 8080 "VoteSpacesTabs" and our function will pause execution waiting for you to step through with the debugger.

Alright, I think we’ve got everything working so let’s deploy this!

First I’ll call the sam package command which is just an alias for aws cloudformation package and then I’ll use the result of that command to sam deploy.

$ sam package --template-file template.yaml --s3-bucket MYAWESOMEBUCKET --output-template-file package.yaml
Uploading to 144e47a4a08f8338faae894afe7563c3  90570 / 90570.0  (100.00%)
Successfully packaged artifacts and wrote output template to file package.yaml.
Execute the following command to deploy the packaged template
aws cloudformation deploy --template-file package.yaml --stack-name 
$ sam deploy --template-file package.yaml --stack-name VoteForSpaces --capabilities CAPABILITY_IAM
Waiting for changeset to be created..
Waiting for stack create/update to complete
Successfully created/updated stack - VoteForSpaces

Which brings us to our API:

I’m going to hop over into the production stage and add some rate limiting in case you guys start voting a lot – but otherwise we’ve taken our local work and deployed it to the cloud without much effort at all. I always enjoy it when things work on the first deploy!

You can vote now and watch the results live! http://spaces-or-tabs.s3-website-us-east-1.amazonaws.com/

We hope that SAM Local makes it easier for you to test, debug, and deploy your serverless apps. We have a CONTRIBUTING.md guide and we welcome pull requests. Please tweet at us to let us know what cool things you build. You can see our What’s New post here and the documentation is live here.


Open and Click Tracking Have Arrived

Post Syndicated from Brent Meyer original https://aws.amazon.com/blogs/ses/open-and-click-tracking-have-arrived/

We’re pleased to announce the addition of open and click tracking metrics to Amazon SES. These metrics will help you measure the effectiveness of the email campaigns you send using Amazon SES.

We’re also adding the ability to publish email sending metrics to Amazon Simple Notification Service (Amazon SNS) using event publishing. This feature gives you greater control over the sending notifications you receive through Amazon SNS.

What’s new in this release?

When you send an email using Amazon SES, we now collect metrics related to opens and clicks. Opens, in this sense, refers to the number of users who successfully received your email and opened it in their email clients; clicks refers to the number of users who received an email and clicked one or more links in it.

Additionally, you can now use event publishing to push email sending notifications—including open and click notifications—using Amazon SNS. Previously, you could send account-level notifications through Amazon SNS. These notifications were pretty limited: you could only receive notifications about bounces, complaints, and deliveries, and you would receive notifications about all of these events across your entire Amazon SES account. Now you can use event publishing to send notifications about deliveries, opens, clicks, bounces, and complaints. Furthermore, you can set up event publishing so that you only receive notifications about emails sent using the configuration sets you specify in those emails.

Why should I use open and click tracking?

Whether you are sending marketing emails, transactional emails, or notifications, you need to know how effective your communications are. The email sending metrics feature of Amazon SES gives you data about entire email response funnel—the total number of emails that were sent, bounced, viewed, and clicked. You can then transform those insights into action.

For example, the open and click tracking feature can help you identify the customers who are most interested in receiving the messages you send. By narrowing down your list of recipients and focusing on your most engaged customers, you can save money (by sending fewer messages), improve the response rates of your marketing campaigns (by targeting only the customers who are most interested in what you have to say), and protect your sender reputation (by reducing the number of bounces and complaints against your sending domain).

How do I enable open and click tracking?

If you’ve set up Sending Metrics in the past, then you can easily add open and click tracking to your existing configuration sets. On the Configuration Sets page, choose the configuration set that contains your sending event destination; edit the event destination, check the boxes for Open and Click (as shown in the image below), and then choose Save.

How does open and click tracking work?

Amazon SES makes very minor changes to your emails in order to make open and click tracking work. At the bottom of each message, we insert a 1 pixel by 1 pixel transparent GIF image. Each email includes a unique link to this image file; when the image is opened, we can tell exactly which message was opened and by whom.

To track clicks, we set up a redirect for each link in the message. When a recipient clicks a link, they are sent to an Amazon SES server, and are immediately forwarded to the destination address. As with open tracking, each of these redirect links is unique, allowing us to easily determine which recipient clicked the link, when they clicked it, and the email from which they arrived at the link.

Can I disable click tracking?

You can disable click tracking by adding a special tag to the anchor tags in your HTML. For example, if you were linking to the AWS home page, a normal anchor link would look something like this:

<a href="https://aws.amazon.com/">Amazon Web Services</a>

To disable click tracking for that same link, you would modify to look like this:

<a ses:no-track href="https://aws.amazon.com/">Amazon Web Services</a>

Because the ses:no-track attribute is non-standard HTML, we automatically remove it from the version of the email that arrives in your recipients’ inboxes.

How do I use event publishing with Amazon SNS?

If you’ve set up event destinations in the past, then the process of setting up an Amazon SNS event destination will be very familiar. You can add an Amazon SNS destination to an existing configuration set, or create a new configuration set that uses Amazon SNS as its event destination. To learn more, see “Set Up an Amazon SNS Event Destination for Amazon SES Event Publishing” in our Developer Guide.

We’re excited about this release. Let us know what you think of these new features in the SES Forum, or in the comments for this post.

AWS HIPAA Eligibility Update (July 2017) – Eight Additional Services

Post Syndicated from Jeff Barr original https://aws.amazon.com/blogs/aws/aws-hipaa-eligibility-update-july-2017-eight-additional-services/

It is time for an update on our on-going effort to make AWS a great host for healthcare and life sciences applications. As you can see from our Health Customer Stories page, Philips, VergeHealth, and Cambia (to choose a few) trust AWS with Protected Health Information (PHI) and Personally Identifying Information (PII) as part of their efforts to comply with HIPAA and HITECH.

In May we announced that we added Amazon API Gateway, AWS Direct Connect, AWS Database Migration Service, and Amazon Simple Queue Service (SQS) to our list of HIPAA eligible services and discussed our how customers and partners are putting them to use.

Eight More Eligible Services
Today I am happy to share the news that we are adding another eight services to the list:

Amazon CloudFront can now be utilized to enhance the delivery and transfer of Protected Health Information data to applications on the Internet. By providing a completely secure and encryptable pathway, CloudFront can now be used as a part of applications that need to cache PHI. This includes applications for viewing lab results or imaging data, and those that transfer PHI from Healthcare Information Exchanges (HIEs).

AWS WAF can now be used to protect applications running on AWS which operate on PHI such as patient care portals, patient scheduling systems, and HIEs. Requests and responses containing encrypted PHI and PII can now pass through AWS WAF.

AWS Shield can now be used to protect web applications such as patient care portals and scheduling systems that operate on encrypted PHI from DDoS attacks.

Amazon S3 Transfer Acceleration can now be used to accelerate the bulk transfer of large amounts of research, genetics, informatics, insurance, or payer/payment data containing PHI/PII information. Transfers can take place between a pair of AWS Regions or from an on-premises system and an AWS Region.

Amazon WorkSpaces can now be used by researchers, informaticists, hospital administrators and other users to analyze, visualize or process PHI/PII data using on-demand Windows virtual desktops.

AWS Directory Service can now be used to connect the authentication and authorization systems of organizations that use or process PHI/PII to their resources in the AWS Cloud. For example, healthcare providers operating hybrid cloud environments can now use AWS Directory Services to allow their users to easily transition between cloud and on-premises resources.

Amazon Simple Notification Service (SNS) can now be used to send notifications containing encrypted PHI/PII as part of patient care, payment processing, and mobile applications.

Amazon Cognito can now be used to authenticate users into mobile patient portal and payment processing applications that use PHI/PII identifiers for accounts.

Additional HIPAA Resources
Here are some additional resources that will help you to build applications that comply with HIPAA and HITECH:

Keep in Touch
In order to make use of any AWS service in any manner that involves PHI, you must first enter into an AWS Business Associate Addendum (BAA). You can contact us to start the process.


Building Loosely Coupled, Scalable, C# Applications with Amazon SQS and Amazon SNS

Post Syndicated from Tara Van Unen original https://aws.amazon.com/blogs/compute/building-loosely-coupled-scalable-c-applications-with-amazon-sqs-and-amazon-sns/

Stephen Liedig, Solutions Architect


One of the many challenges professional software architects and developers face is how to make cloud-native applications scalable, fault-tolerant, and highly available.

Fundamental to your project success is understanding the importance of making systems highly cohesive and loosely coupled. That means considering the multi-dimensional facets of system coupling to support the distributed nature of the applications that you are building for the cloud.

By that, I mean addressing not only the application-level coupling (managing incoming and outgoing dependencies), but also considering the impacts of of platform, spatial, and temporal coupling of your systems. Platform coupling relates to the interoperability, or lack thereof, of heterogeneous systems components. Spatial coupling deals with managing components at a network topology level or protocol level. Temporal, or runtime coupling, refers to the ability of a component within your system to do any kind of meaningful work while it is performing a synchronous, blocking operation.

The AWS messaging services, Amazon SQS and Amazon SNS, help you deal with these forms of coupling by providing mechanisms for:

  • Reliable, durable, and fault-tolerant delivery of messages between application components
  • Logical decomposition of systems and increased autonomy of components
  • Creating unidirectional, non-blocking operations, temporarily decoupling system components at runtime
  • Decreasing the dependencies that components have on each other through standard communication and network channels

Following on the recent topic, Building Scalable Applications and Microservices: Adding Messaging to Your Toolbox, in this post, I look at some of the ways you can introduce SQS and SNS into your architectures to decouple your components, and show how you can implement them using C#.


To illustrate some of these concepts, consider a web application that processes customer orders. As good architects and developers, you have followed best practices and made your application scalable and highly available. Your solution included implementing load balancing, dynamic scaling across multiple Availability Zones, and persisting orders in a Multi-AZ Amazon RDS database instance, as in the following diagram.

In this example, the application is responsible for handling and persisting the order data, as well as dealing with increases in traffic for popular items.

One potential point of vulnerability in the order processing workflow is in saving the order in the database. The business expects that every order has been persisted into the database. However, any potential deadlock, race condition, or network issue could cause the persistence of the order to fail. Then, the order is lost with no recourse to restore the order.

With good logging capability, you may be able to identify when an error occurred and which customer’s order failed. This wouldn’t allow you to “restore” the transaction, and by that stage, your customer is no longer your customer.

As illustrated in the following diagram, introducing an SQS queue helps improve your ordering application. Using the queue isolates the processing logic into its own component and runs it in a separate process from the web application. This, in turn, allows the system to be more resilient to spikes in traffic, while allowing work to be performed only as fast as necessary in order to manage costs.

In addition, you now have a mechanism for persisting orders as messages (with the queue acting as a temporary database), and have moved the scope of your transaction with your database further down the stack. In the event of an application exception or transaction failure, this ensures that the order processing can be retired or redirected to the Amazon SQS Dead Letter Queue (DLQ), for re-processing at a later stage. (See the recent post, Using Amazon SQS Dead-Letter Queues to Control Message Failure, for more information on dead-letter queues.)

Scaling the order processing nodes

This change allows you now to scale the web application frontend independently from the processing nodes. The frontend application can continue to scale based on metrics such as CPU usage, or the number of requests hitting the load balancer. Processing nodes can scale based on the number of orders in the queue. Here is an example of scale-in and scale-out alarms that you would associate with the scaling policy.

Scale-out Alarm

aws cloudwatch put-metric-alarm --alarm-name AddCapacityToCustomerOrderQueue --metric-name ApproximateNumberOfMessagesVisible --namespace "AWS/SQS" 
--statistic Average --period 300 --threshold 3 --comparison-operator GreaterThanOrEqualToThreshold --dimensions Name=QueueName,Value=customer-orders
--evaluation-periods 2 --alarm-actions <arn of the scale-out autoscaling policy>

Scale-in Alarm

aws cloudwatch put-metric-alarm --alarm-name RemoveCapacityFromCustomerOrderQueue --metric-name ApproximateNumberOfMessagesVisible --namespace "AWS/SQS" 
 --statistic Average --period 300 --threshold 1 --comparison-operator LessThanOrEqualToThreshold --dimensions Name=QueueName,Value=customer-orders
 --evaluation-periods 2 --alarm-actions <arn of the scale-in autoscaling policy>

In the above example, use the ApproximateNumberOfMessagesVisible metric to discover the queue length and drive the scaling policy of the Auto Scaling group. Another useful metric is ApproximateAgeOfOldestMessage, when applications have time-sensitive messages and developers need to ensure that messages are processed within a specific time period.

Scaling the order processing implementation

On top of scaling at an infrastructure level using Auto Scaling, make sure to take advantage of the processing power of your Amazon EC2 instances by using as many of the available threads as possible. There are several ways to implement this. In this post, we build a Windows service that uses the BackgroundWorker class to process the messages from the queue.

Here’s a closer look at the implementation. In the first section of the consuming application, use a loop to continually poll the queue for new messages, and construct a ReceiveMessageRequest variable.

public static void PollQueue()
    while (_running)
        Task<ReceiveMessageResponse> receiveMessageResponse;

        // Pull messages off the queue
        using (var sqs = new AmazonSQSClient())
            const int maxMessages = 10;  // 1-10

            //Receiving a message
            var receiveMessageRequest = new ReceiveMessageRequest
                // Get URL from Configuration
                QueueUrl = _queueUrl, 
                // The maximum number of messages to return. 
                // Fewer messages might be returned. 
                MaxNumberOfMessages = maxMessages, 
                // A list of attributes that need to be returned with message.
                AttributeNames = new List<string> { "All" },
                // Enable long polling. 
                // Time to wait for message to arrive on queue.
                WaitTimeSeconds = 5 

            receiveMessageResponse = sqs.ReceiveMessageAsync(receiveMessageRequest);

The WaitTimeSeconds property of the ReceiveMessageRequest specifies the duration (in seconds) that the call waits for a message to arrive in the queue before returning a response to the calling application. There are a few benefits to using long polling:

  • It reduces the number of empty responses by allowing SQS to wait until a message is available in the queue before sending a response.
  • It eliminates false empty responses by querying all (rather than a limited number) of the servers.
  • It returns messages as soon any message becomes available.

For more information, see Amazon SQS Long Polling.

After you have returned messages from the queue, you can start to process them by looping through each message in the response and invoking a new BackgroundWorker thread.

// Process messages
if (receiveMessageResponse.Result.Messages != null)
    foreach (var message in receiveMessageResponse.Result.Messages)
        Console.WriteLine("Received SQS message, starting worker thread");

        // Create background worker to process message
        BackgroundWorker worker = new BackgroundWorker();
        worker.DoWork += (obj, e) => ProcessMessage(message);
    Console.WriteLine("No messages on queue");

The event handler, ProcessMessage, is where you implement business logic for processing orders. It is important to have a good understanding of how long a typical transaction takes so you can set a message VisibilityTimeout that is long enough to complete your operation. If order processing takes longer than the specified timeout period, the message becomes visible on the queue. Other nodes may pick it and process the same order twice, leading to unintended consequences.

Handling Duplicate Messages

In order to manage duplicate messages, seek to make your processing application idempotent. In mathematics, idempotent describes a function that produces the same result if it is applied to itself:

f(x) = f(f(x))

No matter how many times you process the same message, the end result is the same (definition from Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions, Hohpe and Wolf, 2004).

There are several strategies you could apply to achieve this:

  • Create messages that have inherent idempotent characteristics. That is, they are non-transactional in nature and are unique at a specified point in time. Rather than saying “place new order for Customer A,” which adds a duplicate order to the customer, use “place order <orderid> on <timestamp> for Customer A,” which creates a single order no matter how often it is persisted.
  • Deliver your messages via an Amazon SQS FIFO queue, which provides the benefits of message sequencing, but also mechanisms for content-based deduplication. You can deduplicate using the MessageDeduplicationId property on the SendMessage request or by enabling content-based deduplication on the queue, which generates a hash for MessageDeduplicationId, based on the content of the message, not the attributes.
var sendMessageRequest = new SendMessageRequest
    QueueUrl = _queueUrl,
    MessageBody = JsonConvert.SerializeObject(order),
    MessageGroupId = Guid.NewGuid().ToString("N"),
    MessageDeduplicationId = Guid.NewGuid().ToString("N")
  • If using SQS FIFO queues is not an option, keep a message log of all messages attributes processed for a specified period of time, as an alternative to message deduplication on the receiving end. Verifying the existence of the message in the log before processing the message adds additional computational overhead to your processing. This can be minimized through low latency persistence solutions such as Amazon DynamoDB. Bear in mind that this solution is dependent on the successful, distributed transaction of the message and the message log.

Handling exceptions

Because of the distributed nature of SQS queues, it does not automatically delete the message. Therefore, you must explicitly delete the message from the queue after processing it, using the message ReceiptHandle property (see the following code example).

However, if at any stage you have an exception, avoid handling it as you normally would. The intention is to make sure that the message ends back on the queue, so that you can gracefully deal with intermittent failures. Instead, log the exception to capture diagnostic information, and swallow it.

By not explicitly deleting the message from the queue, you can take advantage of the VisibilityTimeout behavior described earlier. Gracefully handle the message processing failure and make the unprocessed message available to other nodes to process.

In the event that subsequent retries fail, SQS automatically moves the message to the configured DLQ after the configured number of receives has been reached. You can further investigate why the order process failed. Most importantly, the order has not been lost, and your customer is still your customer.

private static void ProcessMessage(Message message)
    using (var sqs = new AmazonSQSClient())
            Console.WriteLine("Processing message id: {0}", message.MessageId);

            // Implement messaging processing here
            // Ensure no downstream resource contention (parallel processing)
            // <your order processing logic in here…>
            Console.WriteLine("{0} Thread {1}: {2}", DateTime.Now.ToString("s"), Thread.CurrentThread.ManagedThreadId, message.MessageId);
            // Delete the message off the queue. 
            // Receipt handle is the identifier you must provide 
            // when deleting the message.
            var deleteRequest = new DeleteMessageRequest(_queueName, message.ReceiptHandle);
            Console.WriteLine("Processed message id: {0}", message.MessageId);

        catch (Exception ex)
            // Do nothing.
            // Swallow exception, message will return to the queue when 
            // visibility timeout has been exceeded.
            Console.WriteLine("Could not process message due to error. Exception: {0}", ex.Message);

Using SQS to adapt to changing business requirements

One of the benefits of introducing a message queue is that you can accommodate new business requirements without dramatically affecting your application.

If, for example, the business decided that all orders placed over $5000 are to be handled as a priority, you could introduce a new “priority order” queue. The way the orders are processed does not change. The only significant change to the processing application is to ensure that messages from the “priority order” queue are processed before the “standard order” queue.

The following diagram shows how this logic could be isolated in an “order dispatcher,” whose only purpose is to route order messages to the appropriate queue based on whether the order exceeds $5000. Nothing on the web application or the processing nodes changes other than the target queue to which the order is sent. The rates at which orders are processed can be achieved by modifying the poll rates and scalability settings that I have already discussed.

Extending the design pattern with Amazon SNS

Amazon SNS supports reliable publish-subscribe (pub-sub) scenarios and push notifications to known endpoints across a wide variety of protocols. It eliminates the need to periodically check or poll for new information and updates. SNS supports:

  • Reliable storage of messages for immediate or delayed processing
  • Publish / subscribe – direct, broadcast, targeted “push” messaging
  • Multiple subscriber protocols
  • Amazon SQS, HTTP, HTTPS, email, SMS, mobile push, AWS Lambda

With these capabilities, you can provide parallel asynchronous processing of orders in the system and extend it to support any number of different business use cases without affecting the production environment. This is commonly referred to as a “fanout” scenario.

Rather than your web application pushing orders to a queue for processing, send a notification via SNS. The SNS messages are sent to a topic and then replicated and pushed to multiple SQS queues and Lambda functions for processing.

As the diagram above shows, you have the development team consuming “live” data as they work on the next version of the processing application, or potentially using the messages to troubleshoot issues in production.

Marketing is consuming all order information, via a Lambda function that has subscribed to the SNS topic, inserting the records into an Amazon Redshift warehouse for analysis.

All of this, of course, is happening without affecting your order processing application.


While I haven’t dived deep into the specifics of each service, I have discussed how these services can be applied at an architectural level to build loosely coupled systems that facilitate multiple business use cases. I’ve also shown you how to use infrastructure and application-level scaling techniques, so you can get the most out of your EC2 instances.

One of the many benefits of using these managed services is how quickly and easily you can implement powerful messaging capabilities in your systems, and lower the capital and operational costs of managing your own messaging middleware.

Using Amazon SQS and Amazon SNS together can provide you with a powerful mechanism for decoupling application components. This should be part of design considerations as you architect for the cloud.

For more information, see the Amazon SQS Developer Guide and Amazon SNS Developer Guide. You’ll find tutorials on all the concepts covered in this post, and more. To can get started using the AWS console or SDK of your choice visit:

Happy messaging!