|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
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform and how we integrate our thinking to solve complicated problems. In his session at 19th Cloud Expo, Craig Sproule, CEO of Metavine, demonstrated how to move beyond today's coding paradigm and ...
Dec. 5, 2016 09:29 AM EST
"Venafi has a platform that allows you to manage, centralize and automate the complete life cycle of keys and certificates within the organization," explained Gina Osmond, Sr. Field Marketing Manager at Venafi, in this SYS-CON.tv interview at DevOps at 19th Cloud Expo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 5, 2016 09:15 AM EST Reads: 871
"We are a modern development application platform and we have a suite of products that allow you to application release automation, we do version control, and we do application life cycle management," explained Flint Brenton, CEO of CollabNet, in this SYS-CON.tv interview at DevOps at 19th Cloud Expo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 5, 2016 08:45 AM EST Reads: 793
"ReadyTalk is an audio and web video conferencing provider. We've really come to embrace WebRTC as the platform for our future of technology," explained Dan Cunningham, CTO of ReadyTalk, in this SYS-CON.tv interview at WebRTC Summit at 19th Cloud Expo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 5, 2016 08:15 AM EST Reads: 445
We are always online. We access our data, our finances, work, and various services on the Internet. But we live in a congested world of information in which the roads were built two decades ago. The quest for better, faster Internet routing has been around for a decade, but nobody solved this problem. We’ve seen band-aid approaches like CDNs that attack a niche's slice of static content part of the Internet, but that’s it. It does not address the dynamic services-based Internet of today. It does...
Dec. 5, 2016 07:30 AM EST Reads: 976
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life sett...
Dec. 5, 2016 07:30 AM EST Reads: 7,039
20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
Dec. 5, 2016 06:45 AM EST Reads: 1,793
WebRTC is the future of browser-to-browser communications, and continues to make inroads into the traditional, difficult, plug-in web communications world. The 6th WebRTC Summit continues our tradition of delivering the latest and greatest presentations within the world of WebRTC. Topics include voice calling, video chat, P2P file sharing, and use cases that have already leveraged the power and convenience of WebRTC.
Dec. 5, 2016 06:45 AM EST Reads: 1,594
"We're a cybersecurity firm that specializes in engineering security solutions both at the software and hardware level. Security cannot be an after-the-fact afterthought, which is what it's become," stated Richard Blech, Chief Executive Officer at Secure Channels, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 5, 2016 06:30 AM EST Reads: 730
The Internet of Things (IoT) promises to simplify and streamline our lives by automating routine tasks that distract us from our goals. This promise is based on the ubiquitous deployment of smart, connected devices that link everything from industrial control systems to automobiles to refrigerators. Unfortunately, comparatively few of the devices currently deployed have been developed with an eye toward security, and as the DDoS attacks of late October 2016 have demonstrated, this oversight can ...
Dec. 5, 2016 06:15 AM EST Reads: 891
Internet-of-Things discussions can end up either going down the consumer gadget rabbit hole or focused on the sort of data logging that industrial manufacturers have been doing forever. However, in fact, companies today are already using IoT data both to optimize their operational technology and to improve the experience of customer interactions in novel ways. In his session at @ThingsExpo, Gordon Haff, Red Hat Technology Evangelist, will share examples from a wide range of industries – includin...
Dec. 5, 2016 04:15 AM EST Reads: 1,617
Unless your company can spend a lot of money on new technology, re-engineering your environment and hiring a comprehensive cybersecurity team, you will most likely move to the cloud or seek external service partnerships. In his session at 18th Cloud Expo, Darren Guccione, CEO of Keeper Security, revealed what you need to know when it comes to encryption in the cloud.
Dec. 5, 2016 04:00 AM EST Reads: 4,706
Organizations planning enterprise data center consolidation and modernization projects are faced with a challenging, costly reality. Requirements to deploy modern, cloud-native applications simultaneously with traditional client/server applications are almost impossible to achieve with hardware-centric enterprise infrastructure. Compute and network infrastructure are fast moving down a software-defined path, but storage has been a laggard. Until now.
Dec. 5, 2016 04:00 AM EST Reads: 5,409
We're entering the post-smartphone era, where wearable gadgets from watches and fitness bands to glasses and health aids will power the next technological revolution. With mass adoption of wearable devices comes a new data ecosystem that must be protected. Wearables open new pathways that facilitate the tracking, sharing and storing of consumers’ personal health, location and daily activity data. Consumers have some idea of the data these devices capture, but most don’t realize how revealing and...
Dec. 5, 2016 04:00 AM EST Reads: 5,126
"We are an all-flash array storage provider but our focus has been on VM-aware storage specifically for virtualized applications," stated Dhiraj Sehgal of Tintri in this SYS-CON.tv interview at 19th Cloud Expo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 5, 2016 03:30 AM EST Reads: 686
"We build IoT infrastructure products - when you have to integrate different devices, different systems and cloud you have to build an application to do that but we eliminate the need to build an application. Our products can integrate any device, any system, any cloud regardless of protocol," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 5, 2016 03:30 AM EST Reads: 944
It's easy to assume that your app will run on a fast and reliable network. The reality for your app's users, though, is often a slow, unreliable network with spotty coverage. What happens when the network doesn't work, or when the device is in airplane mode? You get unhappy, frustrated users. An offline-first app is an app that works, without error, when there is no network connection. In his session at 18th Cloud Expo, Bradley Holt, a Developer Advocate with IBM Cloud Data Services, discussed...
Dec. 5, 2016 01:00 AM EST Reads: 3,331
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at 20th Cloud Expo, Ed Featherston, director/senior enterprise architect at Collaborative Consulting, will discuss the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
Dec. 5, 2016 12:45 AM EST Reads: 1,577
Between 2005 and 2020, data volumes will grow by a factor of 300 – enough data to stack CDs from the earth to the moon 162 times. This has come to be known as the ‘big data’ phenomenon. Unfortunately, traditional approaches to handling, storing and analyzing data aren’t adequate at this scale: they’re too costly, slow and physically cumbersome to keep up. Fortunately, in response a new breed of technology has emerged that is cheaper, faster and more scalable. Yet, in meeting these new needs they...
Dec. 5, 2016 12:45 AM EST Reads: 1,816
In addition to all the benefits, IoT is also bringing new kind of customer experience challenges - cars that unlock themselves, thermostats turning houses into saunas and baby video monitors broadcasting over the internet. This list can only increase because while IoT services should be intuitive and simple to use, the delivery ecosystem is a myriad of potential problems as IoT explodes complexity. So finding a performance issue is like finding the proverbial needle in the haystack.
Dec. 5, 2016 12:30 AM EST Reads: 6,099