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How the Internet Works: The Layers of the Cloud

By  Aug 26, 2014

Topics: Web Services, WebSphere, Cloud Computing

Too often the vast majority of online articles and blogs concerning the Cloud talk about the technology through the guise of generalization as if saying "the Cloud" multiple times succinctly and clearly explained everything about "the Cloud"

Well, as a believer in the more knowledge you have the better, below is a quick starter course in Cloud education aimed at peeling back the layers of "Cloud Computing" to introduce you to SaaS, PaaS and IaaS. In this entry of "How the Internet Works", the Cloud is broken down into its core elements.


Like an onion, the Cloud has layers. Not just made up of catchy marketing terms and lingo which goes out of its way to remain obtuse, Cloud Computing is comprised of three major layers - SaaS, PaaS and IaaS. Of the three, IaaS is the foundation while SaaS is the top layer functioning off both PaaS and IaaS. Interestingly enough, although SaaS is normally represented in graphics as the smallest layer of Cloud infrastructure, it is anything but.

In this installment of "How the Internet Works" I will explain, from the foundation up, what the layers of the Cloud accomplish and how each respective layer - IaaS, PaaS, SaaS - operates/feeds into one another.

IaaS - Infrastructure as a Service


IaaS or Infrastructure as a Service refers to the hardware, network equipment and web hosting servers which web hosting companies rent out to consumers. The IaaS layer of Cloud Computing is comprised of all the hardware needed to make Cloud Computing possible. Used day in and day out by network architects (sometimes called NOC's) and web hosting professionals, the IaaS layer is the physical foundation of Cloud Computing which can be and is leased out to users to run their own Cloud based services.

The IaaS layer of Cloud Computing is physical hardware. Regardless of what anyone tells you, the Cloud is based on physical computing hardware (servers, nodes, PDU's, blades, hypervisors, cooling gear etc.) stored in a data center (also called a DC) operated by network architects, network engineers and web hosting professionals/companies. The big take away here: the Cloud is physical and without the IaaS layer, both PaaS and SaaS would not be possible.


PaaS - Platform as a Service


PaaS or Platform as a Service refers to the middle layer of the Cloud used for development by web developers, programmers and coders. The PaaS layer of the Cloud is used by developers and programmers to create applications, programs, software and web tools. PaaS works by developers renting raw hardware from an IaaS provider which can then be used as the platform to build software, applications, programs and web tools.


In most cases, developers will purchase the PaaS layer of the Cloud from infrastructure providers like RackSpace, Amazon EC2, Linode and Digital Ocean. The purchased infrastructure will come with pre-installled developer tools like Apache, MySQL, Ruby, LAMP Stack, Dokku and GitLab etc.

Getting a bit more granular with PaaS, the majority of providers sell PaaS level servers to consumers on a per resource allocation. Whereas you might purchase a car with 255 horsepower, leather seats and heated review mirrors, developers will purchase a Cloud server with a specific allotment of RAM, Disk Space, CPU Cores and Bandwidth. A typical Cloud server might look like 4GB of RAM, 60GB of Disk Space, 4 CPU Cores and 8TB of Bandwidth.

The big take away here: the PaaS layer of the Cloud is based on the IaaS layer of the Cloud and is used to build the highest layer of the Cloud, SaaS applications.


SaaS - Software as a Service


SaaS or Software as a Service is the top most layer of the Cloud. SaaS serves as the layer of the Cloud which the vast majority of consumers utilize. Built on top of both IaaS and PaaS, Software as a Service provides applications, programs, software and web tools to the pubic for free or for a price. Accessible via a computer, tablet or smartphone, the SaaS layer of the Cloud encompasses the largest and most accessible layer of Cloud Computing.



Every time you use the Google Play Store, the App Store, Dropbox, Salesforce, Adobe Cloud Suite, Spotify or any other Cloud based software which is stored in a web server located in a data center halfway around the world, you are accessing the SaaS layer of the Cloud.

As eluded to, the basic premise of SaaS is user friendly software accessed via a computing device of choice stored in a server the world away. A perfect example of SaaS is Microsoft Office 365. Without Microsoft Office 365, a company would be forced to:


  • Purchase individual copies of software or software bundles driving up per seat cost
  • Worry about per seat software upkeep
  • Purchase new versions of software based on a per seat basis

With SaaS enabled Microsoft Office 365:


  • SaaS eliminates per seat software purchases. Companies purchase/rent a license to utilize a single version of the software in question which is stored, maintained and updated in a central server.
  • SaaS eliminates the need for software maintenance, upkeep or upgrade. As the software is hosted by a parent company, the parent company updates the software and that update filters down the line.
  • SaaS enables is scalable. Without SaaS, a company continually purchases new copies of software for new employee. With SaaS, a company rents the license to the software from the hosting company. With new employees, the software is scaled to meet demand.

The big take away here: the SaaS layer of the Cloud is based on both the IaaS and PaaS layers of the Cloud and is used to provide applications to the market at a lower cost and lower local hardware resource need. SaaS is scalable, more affordable and easier to maintain than traditional software bundles.




In my next "How the Internet Works", I am going to cover virtualization and load balancing, both of which are natural offshoots of this conversation...If you have any topics you want me to cover in in a forthcoming "How the Internet Works" , feel free to leave them in the comments below or email me.

Remember, if you like this content and want to chat about it, you can reach me at the following social spaces:

Part one of "How the Internet Works: TCP/IP, Trace Routes and Hops"


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