|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
With SaaS use rampant across organizations, how can IT departments track company data and maintain security? More and more departments are commissioning their own solutions and bypassing IT. A cloud environment is amorphous and powerful, allowing you to set up solutions for all of your user needs: document sharing and collaboration, mobile access, e-mail, even industry-specific applications. In his session at 16th Cloud Expo, Shawn Mills, President and a founder of Green House Data, discussed h...
Jul. 30, 2015 07:45 AM EDT Reads: 333
One of the hottest areas in cloud right now is DRaaS and related offerings. In his session at 16th Cloud Expo, Dale Levesque, Disaster Recovery Product Manager with Windstream's Cloud and Data Center Marketing team, will discuss the benefits of the cloud model, which far outweigh the traditional approach, and how enterprises need to ensure that their needs are properly being met.
Jul. 30, 2015 07:00 AM EDT Reads: 1,671
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, explained the best practices of continuous testing at high scale, which is rele...
Jul. 29, 2015 11:45 PM EDT Reads: 1,367
[video] Logging and Monitoring with @Sematext Founder @OtisG | @DevOpsSummit #DevOps #Logging #Monitoring
"We got started as search consultants. On the services side of the business we have help organizations save time and save money when they hit issues that everyone more or less hits when their data grows," noted Otis Gospodnetić, Founder of Sematext, in this SYS-CON.tv interview at @DevOpsSummit, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 29, 2015 11:45 PM EDT Reads: 1,022
"We have been in business for 21 years and have been building many enterprise solutions, all IT plumbing - server, storage, interconnects," stated Alex Gorbachev, President of Intelligent Systems Services, in this SYS-CON.tv interview at 16th Cloud Expo, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 29, 2015 10:45 PM EDT Reads: 1,027
"We specialize in testing. DevOps is all about continuous delivery and accelerating the delivery pipeline and there is no continuous delivery without testing," noted Marc Hornbeek, Sr. Solutions Architect at Spirent Communications, in this SYS-CON.tv interview at @DevOpsSummit, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 29, 2015 05:15 PM EDT Reads: 363
"Alert Logic is a managed security service provider that basically deploys technologies, but we support those technologies with the people and process behind it," stated Stephen Coty, Chief Security Evangelist at Alert Logic, in this SYS-CON.tv interview at 16th Cloud Expo, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 29, 2015 04:15 PM EDT Reads: 328
Take the Long View with Digital Transformation By @IoT2040 | @ThingsExpo #IoT #M2M #API #Microservices #InternetOfThings
Digital Transformation is the ultimate goal of cloud computing and related initiatives. The phrase is certainly not a precise one, and as subject to hand-waving and distortion as any high-falutin' terminology in the world of information technology. Yet it is an excellent choice of words to describe what enterprise IT—and by extension, organizations in general—should be working to achieve. Digital Transformation means: handling all the data types being found and created in the organizat...
Jul. 29, 2015 04:00 PM EDT Reads: 1,070
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.
Jul. 29, 2015 03:15 PM EDT Reads: 244
The essence of cloud computing is that all consumable IT resources are delivered as services. In his session at 15th Cloud Expo, Yung Chou, Technology Evangelist at Microsoft, demonstrated the concepts and implementations of two important cloud computing deliveries: Infrastructure as a Service (IaaS) and Platform as a Service (PaaS). He discussed from business and technical viewpoints what exactly they are, why we care, how they are different and in what ways, and the strategies for IT to tran...
Jul. 29, 2015 03:15 PM EDT Reads: 396
The Software Defined Data Center (SDDC), which enables organizations to seamlessly run in a hybrid cloud model (public + private cloud), is here to stay. IDC estimates that the software-defined networking market will be valued at $3.7 billion by 2016. Security is a key component and benefit of the SDDC, and offers an opportunity to build security 'from the ground up' and weave it into the environment from day one. In his session at 16th Cloud Expo, Reuven Harrison, CTO and Co-Founder of Tufin,...
Jul. 29, 2015 03:00 PM EDT Reads: 469
The Internet of Things is not only adding billions of sensors and billions of terabytes to the Internet. It is also forcing a fundamental change in the way we envision Information Technology. For the first time, more data is being created by devices at the edge of the Internet rather than from centralized systems. What does this mean for today's IT professional? In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists addressed this very serious issue of pro...
Jul. 29, 2015 03:00 PM EDT Reads: 1,258
Container technology is sending shock waves through the world of cloud computing. Heralded as the 'next big thing,' containers provide software owners a consistent way to package their software and dependencies while infrastructure operators benefit from a standard way to deploy and run them. Containers present new challenges for tracking usage due to their dynamic nature. They can also be deployed to bare metal, virtual machines and various cloud platforms. How do software owners track the usag...
Jul. 29, 2015 02:30 PM EDT Reads: 115
Discussions about cloud computing are evolving into discussions about enterprise IT in general. As enterprises increasingly migrate toward their own unique clouds, new issues such as the use of containers and microservices emerge to keep things interesting. In this Power Panel at 16th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the state of cloud computing today, and what enterprise IT professionals need to know about how the latest topics and trends affect t...
Jul. 29, 2015 02:00 PM EDT Reads: 1,172
"Our biggest growth area has been the security services, the managed services - the things that differentiate us in the market that there is no client that's too small and there's no client that's too big," explained Paul Mazzucco, Chief Security Officer at TierPoint, in this SYS-CON.tv interview at 16th Cloud Expo, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 29, 2015 02:00 PM EDT Reads: 377
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
Jul. 29, 2015 01:45 PM EDT Reads: 426
[video] Infrastructure as a Toolbox By @SoftLayer at @CloudExpo New York | #IoT #API #Containers #Microservices
Countless business models have spawned from the IaaS industry. Resell Web hosting, blogs, public cloud, and on and on. With the overwhelming amount of tools available to us, it's sometimes easy to overlook that many of them are just new skins of resources we've had for a long time. In his General Session at 16th Cloud Expo, Phil Jackson, Lead Technology Evangelist at SoftLayer, broke down what we've got to work with and discuss the benefits and pitfalls to discover how we can best use them to d...
Jul. 29, 2015 01:00 PM EDT Reads: 1,949
[session] The Container New World By @KeGilpin | @DevOpsSummit #DevOps #Docker #Containers #Microservices
Containers are changing the security landscape for software development and deployment. As with any security solutions, security approaches that work for developers, operations personnel and security professionals is a requirement. In his session at DevOps Summit, Kevin Gilpin, CTO and Co-Founder of Conjur, will discuss various security considerations for container-based infrastructure and related DevOps workflows.
Jul. 29, 2015 01:00 PM EDT Reads: 1,062
"We do data integration for B2B also application to application, and we do data management and enable Big Data," explained Pat Adamiak, Vice President, Product Marketing at Liaison Technologies, in this SYS-CON.tv interview at 16th Cloud Expo, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 29, 2015 12:00 PM EDT Reads: 335
The Cloud industry has moved from being more than just being able to provide infrastructure and management services on the Cloud. Enter a new era of Cloud computing where monetization’s services through the Cloud are an essential piece of strategy to feed your organizations bottom-line, your revenue and Profitability. In their session at 16th Cloud Expo, Ermanno Bonifazi, CEO & Founder of Solgenia, and Ian Khan, Global Strategic Positioning & Brand Manager at Solgenia, discussed how to easily o...
Jul. 29, 2015 11:00 AM EDT Reads: 364