|By Mario Meir-Huber||
|May 20, 2012 02:00 PM EDT||
Infrastructure as a Service and Platform as a Service offer us easy scaling of services. However, scaling is not as easy as it seems to be in the Cloud. If your software architecture isn't done right, your services and applications might not scale as expected, even if you add new instances. As for most distributed systems, there are a couple of guidelines you should consider. I have summed up the ones I use most often for designing distributed systems.
Design for Failure
As Moore stated, everything that can fail, will fail. So it is very clear that a distributed system will fail at a certain time, even though cloud computing providers tell us that it is very unlikely. We had some outages  in the last year of some of the major platforms, and there might be even more of them. Therefore, your application should be able to deal with an outage of your cloud provider. This can be done with different techniques such as distributing an application in more than one availability zone (which should be done anyway). Netflix has a very interesting approach to steadily test their software for errors - they have employed an army of "Chaos Monkeys" . Of course, they are not real monkeys. It is software that randomly takes down different Instances. Netflix produces errors on purpose to see how their system reacts and if it is still performing well. The question is not if there will be another outage; the question is when the next outage will be.
Design for at Least Three Running Systems
For on-premise systems, we always used to do an "N+1" Design. This still applies in the cloud. There should always be one more system available than actually necessary. In the cloud, this can easily be achieved by running your instances in different geographical locations and availability zones. In case one region fails, the other region will take over. Some platforms offer intelligent routing and can easily forward traffic to another zone if one zone is down. However, there is this "rule of three," that basically says you should have three systems available: one for me, one for the customer and one if there is a failure. This will minimize the risk of an outage significantly for you.
Design for Monitoring
We all need to know what is going on in our datacenters and on our systems. Therefore, monitoring is an important aspect for every application you build. If you want to design intelligent monitoring, I/O performance or other metrics are not the only important things. It would be best if your system could "predict" your future load - this could either be done by statistical data you have from your applications‘ history or from your applications‘ domain. If your application is on sports betting, you might have high load on during major sports events. If it is for social games, your load might be higher during the day or when the weather is bad outside. However, your system should be monitored all the time and it should tell you in case a major failure might come up.
Design for Rollback
Large systems are typically owned by different teams in your company. This means that a lot of people work on your systems and rollout happens often. Even though there should be a lot of testing involved, it will still happen that new features will affect other services of your application. To prevent from that, our application should allow an easy rollback mechanism.
Design No State
State kills. If you store states on your systems, this will make load balancing much more complicated for you. State should be eliminated wherever and whenever possible. There are several techniques to reduce or remove state in your application. Modern devices such as tablets or smartphones have sufficient performance to store state information on the client. Every service call should be independent and it shouldn‘t be necessary to have a session state on the server. All session state should be transferred to the client, as described by Roy Fielding . Architectural styles such as ROA support this idea and help you make your services stateless. I will dig into ReST and ROA in one of my upcoming articles since this is really great for distributed systems.
Design to Disable Services
It should be easy to disable services that are not performing well or influencing your system in a way that is poisoning the entire application. Therefore, it will be important to isolate each service from each other, since it should not affect the entire system's functionality. Imagine the comment function of Amazon is not working - this might be essential to make up your mind about buying a book, but it wouldn't prevent you from buying the book.
Design Different Roles
However, with distributed systems we have a lot of servers involved - and it‘s necessary not to scale a front-end or back-end server, but to scale individual services. If there is exactly one front-end system that hosts all roles and a specific service experiences high load, why would it be necessary to scale up all services, even those services that have minor load? You might improve your systems if you have them split up in different roles. As already described by Bertram Meyer  with Command Query Separation, your application should also be split in different roles. This is basically a key thing for SOA applications; however, I still see that most services are not separated. There should be more separation of concerns based on the services. Implement some kind of application role separation for your application and services to improve scaling.
There might be additional principles for distributed systems. I see this article as a rather "living" one and will extend it over the time. I would be interested is your feedback on this. What are your thoughts on distributed systems? Email me at [email protected], use the comment section here or get in touch with me via Twitter at @mario_mh
VictorOps is making on-call suck less with the only collaborative alert management platform on the market. With easy on-call scheduling management, a real-time incident timeline that gives you contextual relevance around your alerts and powerful reporting features that make post-mortems more effective, VictorOps helps your IT/DevOps team solve problems faster.
Mar. 1, 2015 05:00 PM EST Reads: 1,221
Skeuomorphism usually means retaining existing design cues in something new that doesn’t actually need them. However, the concept of skeuomorphism can be thought of as relating more broadly to applying existing patterns to new technologies that, in fact, cry out for new approaches. In his session at DevOps Summit, Gordon Haff, Senior Cloud Strategy Marketing and Evangelism Manager at Red Hat, will discuss why containers should be paired with new architectural practices such as microservices ra...
Mar. 1, 2015 04:00 PM EST Reads: 1,445
Roberto Medrano, Executive Vice President at SOA Software, had reached 30,000 page views on his home page - http://RobertoMedrano.SYS-CON.com/ - on the SYS-CON family of online magazines, which includes Cloud Computing Journal, Internet of Things Journal, Big Data Journal, and SOA World Magazine. He is a recognized executive in the information technology fields of SOA, internet security, governance, and compliance. He has extensive experience with both start-ups and large companies, having been ...
Mar. 1, 2015 04:00 PM EST Reads: 1,234
The industrial software market has treated data with the mentality of “collect everything now, worry about how to use it later.” We now find ourselves buried in data, with the pervasive connectivity of the (Industrial) Internet of Things only piling on more numbers. There’s too much data and not enough information. In his session at @ThingsExpo, Bob Gates, Global Marketing Director, GE’s Intelligent Platforms business, to discuss how realizing the power of IoT, software developers are now focu...
Mar. 1, 2015 03:15 PM EST Reads: 1,352
Operational Hadoop and the Lambda Architecture for Streaming Data Apache Hadoop is emerging as a distributed platform for handling large and fast incoming streams of data. Predictive maintenance, supply chain optimization, and Internet-of-Things analysis are examples where Hadoop provides the scalable storage, processing, and analytics platform to gain meaningful insights from granular data that is typically only valuable from a large-scale, aggregate view. One architecture useful for capturing...
Mar. 1, 2015 02:00 PM EST Reads: 1,338
SYS-CON Events announced today that Vitria Technology, Inc. will exhibit at SYS-CON’s @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Vitria will showcase the company’s new IoT Analytics Platform through live demonstrations at booth #330. Vitria’s IoT Analytics Platform, fully integrated and powered by an operational intelligence engine, enables customers to rapidly build and operationalize advanced analytics to deliver timely business outcomes ...
Mar. 1, 2015 01:45 PM EST Reads: 1,213
DevOps is about increasing efficiency, but nothing is more inefficient than building the same application twice. However, this is a routine occurrence with enterprise applications that need both a rich desktop web interface and strong mobile support. With recent technological advances from Isomorphic Software and others, it is now feasible to create a rich desktop and tuned mobile experience with a single codebase, without compromising performance or usability.
Mar. 1, 2015 01:15 PM EST Reads: 1,112
SYS-CON Events announced today Arista Networks will exhibit at SYS-CON's DevOps Summit 2015 New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Arista Networks was founded to deliver software-driven cloud networking solutions for large data center and computing environments. Arista’s award-winning 10/40/100GbE switches redefine scalability, robustness, and price-performance, with over 3,000 customers and more than three million cloud networking ports depl...
Mar. 1, 2015 01:00 PM EST Reads: 1,559
The speed of software changes in growing and large scale rapid-paced DevOps environments presents a challenge for continuous testing. Many organizations struggle to get this right. Practices that work for small scale continuous testing may not be sufficient as the requirements grow. In his session at DevOps Summit, Marc Hornbeek, Sr. Solutions Architect of DevOps continuous test solutions at Spirent Communications, will explain the best practices of continuous testing at high scale, which is r...
Mar. 1, 2015 01:00 PM EST Reads: 1,189
SYS-CON Events announced today that Open Data Centers (ODC), a carrier-neutral colocation provider, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Open Data Centers is a carrier-neutral data center operator in New Jersey and New York City offering alternative connectivity options for carriers, service providers and enterprise customers.
Mar. 1, 2015 12:00 PM EST Reads: 1,916
Thanks to Docker, it becomes very easy to leverage containers to build, ship, and run any Linux application on any kind of infrastructure. Docker is particularly helpful for microservice architectures because their successful implementation relies on a fast, efficient deployment mechanism – which is precisely one of the features of Docker. Microservice architectures are therefore becoming more popular, and are increasingly seen as an interesting option even for smaller projects, instead of bein...
Mar. 1, 2015 12:00 PM EST Reads: 2,563
Security can create serious friction for DevOps processes. We've come up with an approach to alleviate the friction and provide security value to DevOps teams. In her session at DevOps Summit, Shannon Lietz, Senior Manager of DevSecOps at Intuit, will discuss how DevSecOps got started and how it has evolved. Shannon Lietz has over two decades of experience pursuing next generation security solutions. She is currently the DevSecOps Leader for Intuit where she is responsible for setting and driv...
Mar. 1, 2015 12:00 PM EST Reads: 2,370
The explosion of connected devices / sensors is creating an ever-expanding set of new and valuable data. In parallel the emerging capability of Big Data technologies to store, access, analyze, and react to this data is producing changes in business models under the umbrella of the Internet of Things (IoT). In particular within the Insurance industry, IoT appears positioned to enable deep changes by altering relationships between insurers, distributors, and the insured. In his session at @Things...
Mar. 1, 2015 12:00 PM EST Reads: 1,266
Even as cloud and managed services grow increasingly central to business strategy and performance, challenges remain. The biggest sticking point for companies seeking to capitalize on the cloud is data security. Keeping data safe is an issue in any computing environment, and it has been a focus since the earliest days of the cloud revolution. Understandably so: a lot can go wrong when you allow valuable information to live outside the firewall. Recent revelations about government snooping, along...
Mar. 1, 2015 11:00 AM EST Reads: 6,961
In his session at DevOps Summit, Tapabrata Pal, Director of Enterprise Architecture at Capital One, will tell a story about how Capital One has embraced Agile and DevOps Security practices across the Enterprise – driven by Enterprise Architecture; bringing in Development, Operations and Information Security organizations together. Capital Ones DevOpsSec practice is based upon three "pillars" – Shift-Left, Automate Everything, Dashboard Everything. Within about three years, from 100% waterfall, C...
Mar. 1, 2015 11:00 AM EST Reads: 2,723
PubNub on Monday has announced that it is partnering with IBM to bring its sophisticated real-time data streaming and messaging capabilities to Bluemix, IBM’s cloud development platform. “Today’s app and connected devices require an always-on connection, but building a secure, scalable solution from the ground up is time consuming, resource intensive, and error-prone,” said Todd Greene, CEO of PubNub. “PubNub enables web, mobile and IoT developers building apps on IBM Bluemix to quickly add sc...
Mar. 1, 2015 10:00 AM EST Reads: 4,755
Data-intensive companies that strive to gain insights from data using Big Data analytics tools can gain tremendous competitive advantage by deploying data-centric storage. Organizations generate large volumes of data, the vast majority of which is unstructured. As the volume and velocity of this unstructured data increases, the costs, risks and usability challenges associated with managing the unstructured data (regardless of file type, size or device) increases simultaneously, including end-to-...
Mar. 1, 2015 09:45 AM EST Reads: 2,205
The excitement around the possibilities enabled by Big Data is being tempered by the daunting task of feeding the analytics engines with high quality data on a continuous basis. As the once distinct fields of data integration and data management increasingly converge, cloud-based data solutions providers have emerged that can buffer your organization from the complexities of this continuous data cleansing and management so that you’re free to focus on the end goal: actionable insight.
Mar. 1, 2015 09:30 AM EST Reads: 1,670
With several hundred implementations of IoT-enabled solutions in the past 12 months alone, this session will focus on experience over the art of the possible. Many can only imagine the most advanced telematics platform ever deployed, supporting millions of customers, producing tens of thousands events or GBs per trip, and hundreds of TBs per month. With the ability to support a billion sensor events per second, over 30PB of warm data for analytics, and hundreds of PBs for an data analytics arc...
Mar. 1, 2015 09:00 AM EST Reads: 1,284
Between the compelling mockups and specs produced by your analysts and designers, and the resulting application built by your developers, there is a gulf where projects fail, costs spiral out of control, and applications fall short of requirements. In his session at DevOps Summit, Charles Kendrick, CTO and Chief Architect at Isomorphic Software, will present a new approach where business and development users collaborate – each using tools appropriate to their goals and expertise – to build mo...
Mar. 1, 2015 09:00 AM EST Reads: 2,913