What is cloud computing, really? If you are confused by all the talk about moving to “the cloud” and having trouble pinning down what that actually means, there’s a reason for that: Cloud isn’t a technology, it’s a metaphor.
At one time, users had no fancy software on their computers, just simple programs (“terminals”) that they used to access a big central computer for them.
Sometimes it wasn’t just a wire between the user’s terminal and the big computer, it was a network with many wires and many devices. But most people didn’t need all those details so we used a cloud to represent all that hidden complexity.
When we got “personal computers” (PC’s) with software running right on them, and then the Internet sprouted up alongside corporate and phone company networks, the cloud metaphor was a handy way of distinguishing who controlled which network.
The cloud metaphor was now pervasive in tech circles and became part of our everyday tech lingo, so we applied it to a new set of services that are run by someone else, over networks, and offered to you as a service, and we called them cloud services. Cloud is the shorthand for those characteristics.
Sounds straight forward, right? The reason it seems more complicated is that we’re using the cloud metaphor for a wide variety of services. Fortunately they break down into three types:
• Software as a Service (SaaS)
• Platform as a Service (PaaS)
• Infrastructure as a Service (IaaS)
Most people really only need to know about SaaS. Instead of downloading a huge file that then runs a application locally on your machine, you access the application by visiting a website. If you’re using things like Gmail, SalesForce, or Office365, you’re using cloud applications. It’s that simple. You aren’t buying or running the actual software, you’re just using it and someone else is operating it. We mostly think of third-party SaaS where the “cloud” is the Internet, although sometimes your IT department will build and operate SaaS just for your company or put in private network connections to the SaaS provider. For the average user, that’s all just SaaS.
Software developers use SaaS just like end users but they also have their own set of cloud services that we call PaaS, or Platform as a Service. Platforms like Amazon Cloud and Microsoft Azure have integrated a lot of different software that developers use and deployed them on huge platforms. Instead of looking to IT to build, upgrade an manage platforms for each development project, developers just access the PaaS and pay for as much or as little as they need.
The last category is for IT departments. Infrastructure as a Service (IaaS) is just what it sounds like – technology infrastructure (like storage, computing power, servers and security) that’s running “in the cloud”. Your IT department can pay to use instead of deploying it themselves. Just like SaaS and PaaS, IaaS can be run privately just for your company, publicly for anyone to use, or a hybrid of the two. But essentially it’s the same as the other cloud services – big sets of hardware and software accessed as needed.
In future columns, we will explore why companies choose SaaS, PaaS and IaaS cloud services, and some of the pros and cons. We’ll also talk about the characteristics of cloud services that make them valuable.
But for today, here’s your takeaway:
At its heart, cloud is just a metaphor for computing resources delivered “as a Service”
