Architecting on AWS: Optimizing the Application Design

In our practice, we hear a variety of misconceptions and misinterpretations in relation to the benefits of moving workloads ‘into the cloud’. You should be very wary if someone wants to make you believe that the pure migration of a traditional application to a cloud services vendor will make it any more scalable or reliable. Of course, you can scale vertically in increasing the size of your compute nodes. However, this still restricts you to the maximum size of the instances available. Scaling horizontally on the other hand, in distributing your workload over multiple instances, requires special considerations with regard to optimizing the application design.

As part of your migration strategy, you should also critically review your existing application components and consider if any of the high-level capabilities provided by your cloud vendor can deliver the same functionality at reduced costs, increased reliability, higher flexibility, et cetera. The story on how this startup ditched AWS from marketing software provider Moz also serves as a timely reminder that your mileage may vary depending on the type of your workload and non-functional requirements. Therefore we can only provide a general guide as each option needs to be considered against its advantages and disadvantages against the overall solution.

Please note that we tend to angle our posts along the service catalog of Amazon Web Services (AWS). However, most of the strategies and patterns we describe will also apply to other cloud vendors that provide capabilities with similar characteristics. With that in mind, let’s review our two-tier example application from the first post on Architecting on AWS: the best services to build a two-tier application from this series. To support the elasticity and reliability of our solution, we should consider a few concerns from the application perspective.

Optimizing the application design: session management

In the design, we are using the Elastic Load Balancer (ELB) for the distribution of load between instances. By default, the ELB routes each request to the instance with the smallest load. This is also referred to as stateless load balancing and needs to be considered in the design of your application. Unless you are having strong reasons to store your session state in memory on the web server, you should migrate to an external session provider. A common approach for this is the use of a session table within a relational database system. However, this doesn’t come without risks as the database system may be unnecessarily flooded with session requests. This is potentially impacting on the overall performance of the application and causing scalability issues in the database tier.

On AWS you are better off to use DynamoDB. Amazon DynamoDB is a key-value data store (with recently added support for document data model) which delivers configurable, predictable performance. For that reason, DynamoDB is an ideal candidate to consider for the management of session state. As a fully managed service, you won’t even have to worry about any operational or administrative cost.
Provisioned Throughput capacity on AWS

A word on RDS and scaling

If you are an observant reader you may have already spotted a snag. If you really want your overall solution to be truly scalable, you need to ensure that this is applied to each tier of the application. This is posing a couple of issues in the traditional relational database space. While you have the ability to ‘crank-up’ the amount of provisioned IOPS for your RDS instances, there is no ability to autoscale database instances in the same fashion as EC2.

A common design pattern is the separation of write operations from read operations. By the general nature of storage systems read operations tend to be proportionally higher than database write operations. For that reason, you can offload read requests to a dedicated (set of) read replicas to provide some level of scalability. Based on the underlying design limitations within the storage engines though, this cannot be provided fully automated. Amongst other limitations, we also need to highlight that the support of read replicas in RDS is limited to MySQL, PostgreSQL and the new Aurora storage engines.

Alternative database technologies

All this is obviously not going to be an issue for you if you are dealing with very steady and predictable workloads. If you do have the need to deliver a scalable solution though, you will eventually get to the stage where you need to consider alternative mechanisms to reduce the load on your relational database environment. An obvious choice would be the consideration of alternative database technologies like Amazon DynamoDB or Amazon SimpleDB for the data that doesn’t require a relational structure.

Content distribution

You can also reduce the strain on your application and database services in employing caching services like Amazon CloudFront. As described in a previous post, CloudFront provides a large number of edge locations across the globe that act like a massive cache for web and streaming content. The cache behaviour settings allow you to optimise the cache behaviour for the unique needs of your application. As an added bonus this will also improve the overall user experience for your customers.
Default Cache Behaviour Settings

Object storage

Finally, we briefly want to touch on the Amazon S3 storage service. Again, many traditional application designs make us of relational or file system resources for the storage of BLOB objects. While you can certainly continue on that path, we recommend to rethink that approach for a number of reasons. For one, you obviously need to continue to provide and manage your own file system or relational database environment. You also have to ensure that the systems are always up-to-date, ensure that you have got enough available disk space available and the systems are actually available to meet your service level agreements.

If those operational reasons haven’t put you off yet, you may want to consider the actual costs for storage. Based on the figures for my ‘home’ region Sydney, the cost of storing 100 GByte of data on S3 is approximately 30% of the cost of Elastic Block Storage or RDS. And the pure cost of storage doesn’t even include the cost for utility compute to power the relational database or file system environments. So unless there is a specific need for a direct attached, high performing local disk e.g. for the hosting of a COTS solution like SAP, we strongly recommend to consider the use of the S3 object store where applicable.

With those initial teasers in mind, you should start exploring the AWS service catalogue and our rich training content on Cloud Academy to consider what other services you could utilise to address the unique concerns of your solution.

Avatar

Written by

Christian Petters

As a Solutions Architect, Christian is helping organisations to find the most appropriate solution to address their unique business problems. He is passionate about the opportunities that are provided by modern cloud services and covers topics in AWS and MS Azure with a particular focus on Microsoft technologies.

Related Posts

Avatar
Jeremy Cook
— September 17, 2019

Cloud Migration Risks & Benefits

If you’re like most businesses, you already have at least one workload running in the cloud. However, that doesn’t mean that cloud migration is right for everyone. While cloud environments are generally scalable, reliable, and highly available, those won’t be the only considerations dri...

Read more
  • AWS
  • Azure
  • Cloud Migration
Joe Nemer
Joe Nemer
— September 12, 2019

Real-Time Application Monitoring with Amazon Kinesis

Amazon Kinesis is a real-time data streaming service that makes it easy to collect, process, and analyze data so you can get quick insights and react as fast as possible to new information.  With Amazon Kinesis you can ingest real-time data such as application logs, website clickstre...

Read more
  • amazon kinesis
  • AWS
  • Stream Analytics
  • Streaming data
Joe Nemer
Joe Nemer
— September 6, 2019

Google Cloud Functions vs. AWS Lambda: The Fight for Serverless Cloud Domination

Serverless computing: What is it and why is it important? A quick background The general concept of serverless computing was introduced to the market by Amazon Web Services (AWS) around 2014 with the release of AWS Lambda. As we know, cloud computing has made it possible for users to ...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
Joe Nemer
Joe Nemer
— September 3, 2019

Google Vision vs. Amazon Rekognition: A Vendor-Neutral Comparison

Google Cloud Vision and Amazon Rekognition offer a broad spectrum of solutions, some of which are comparable in terms of functional details, quality, performance, and costs. This post is a fact-based comparative analysis on Google Vision vs. Amazon Rekognition and will focus on the tech...

Read more
  • Amazon Rekognition
  • AWS
  • Google Cloud Platform
  • Google Vision
Alisha Reyes
Alisha Reyes
— August 30, 2019

New on Cloud Academy: CISSP, AWS, Azure, & DevOps Labs, Python for Beginners, and more…

As Hurricane Dorian intensifies, it looks like Floridians across the entire state might have to hunker down for another big one. If you've gone through a hurricane, you know that preparing for one is no joke. You'll need a survival kit with plenty of water, flashlights, batteries, and n...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
  • New content
  • Product Feature
  • Python programming
Joe Nemer
Joe Nemer
— August 27, 2019

Amazon Route 53: Why You Should Consider DNS Migration

What Amazon Route 53 brings to the DNS table Amazon Route 53 is a highly available and scalable Domain Name System (DNS) service offered by AWS. It is named by the TCP or UDP port 53, which is where DNS server requests are addressed. Like any DNS service, Route 53 handles domain regist...

Read more
  • Amazon
  • AWS
  • Cloud Migration
  • DNS
  • Route 53
Alisha Reyes
Alisha Reyes
— August 22, 2019

How to Unlock Complimentary Access to Cloud Academy

Are you looking to get trained or certified on AWS, Azure, Google Cloud Platform, DevOps, Cloud Security, Python, Java, or another technical skill? Then you'll want to mark your calendars for August 23, 2019. Starting Friday at 12:00 a.m. PDT (3:00 a.m. EDT), Cloud Academy is offering c...

Read more
  • AWS
  • Azure
  • cloud academy content
  • complimentary access
  • GCP
  • on the house
Avatar
Michael Sheehy
— August 19, 2019

What Exactly Is a Cloud Architect and How Do You Become One?

One of the buzzwords surrounding the cloud that I'm sure you've heard is "Cloud Architect." In this article, I will outline my understanding of what a cloud architect does and I'll analyze the skills and certifications necessary to become one. I will also list some of the types of jobs ...

Read more
  • AWS
  • Cloud Computing
Avatar
Nitheesh Poojary
— August 19, 2019

Boto: Using Python to Automate AWS Services

Boto allows you to write scripts to automate things like starting AWS EC2 instances Boto is a Python package that provides programmatic connectivity to Amazon Web Services (AWS). AWS offers a range of services for dynamically scaling servers including the core compute service, Elastic...

Read more
  • Automated AWS Services
  • AWS
  • Boto
  • Python
Avatar
Andrew Larkin
— August 13, 2019

Content Roadmap: AZ-500, ITIL 4, MS-100, Google Cloud Associate Engineer, and More

Last month, Cloud Academy joined forces with QA, the UK’s largest B2B skills provider, and it put us in an excellent position to solve a massive skills gap problem. As a result of this collaboration, you will see our training library grow with additions from QA’s massive catalog of 500+...

Read more
  • AWS
  • Azure
  • content roadmap
  • Google Cloud Platform
Avatar
Adam Hawkins
— August 9, 2019

DevSecOps: How to Secure DevOps Environments

Security has been a friction point when discussing DevOps. This stems from the assumption that DevOps teams move too fast to handle security concerns. This makes sense if Information Security (InfoSec) is separate from the DevOps value stream, or if development velocity exceeds the band...

Read more
  • AWS
  • cloud security
  • DevOps
  • DevSecOps
  • Security
Avatar
Stefano Giacone
— August 8, 2019

Test Your Cloud Knowledge on AWS, Azure, or Google Cloud Platform

Cloud skills are in demand | In today's digital era, employers are constantly seeking skilled professionals with working knowledge of AWS, Azure, and Google Cloud Platform. According to the 2019 Trends in Cloud Transformation report by 451 Research: Business and IT transformations re...

Read more
  • AWS
  • Cloud skills
  • Google Cloud
  • Microsoft Azure