I am often reminded of a specific parable whenever someone drops the words ‘cloud’, ‘private cloud’, ‘hybrid cloud‘ or ‘SaaS’. It’s the one about the blind men and an elephant, who describe the animal based on which part of its anatomy they feel, then come to blows because they assume the others are being dishonest. Software engineers and architects often have strong opinions on what the best architecture, application or methodology is to solve a problem, but can agree often enough about how frustratingly easy it is for customers to mistakenly interchange terms without considering the ways in which they differ from each other.

This blog entry isn’t about the uses of cloud computing — remotely hosted infrastructure and services used to transmit, process, manage and store data — or how it works. It is not why you should have a cloud strategy, or in terms of cost, scale, productivity, performance, and reliability with respect to the development, delivery or consumption of solutions. The intent is to help make sense of some of the language pertaining to cloud and what commonly differentiates a private cloud from a public one, what a hybrid cloud refers to, and why it is a mistake to assume SaaS and the cloud mean one and the same thing.

Let’s start with the three different ways to deploy cloud computing resources: Public Cloud, Private Cloud, and Hybrid Cloud.

Public Cloud: Fun For Everyone

Whenever you hear the word ‘cloud’, chances are it is the public cloud you have in mind. This is because of how large it really is, and how it can involve everything from applications and data storage to infrastructure. Public cloud resources are owned and operated by a third-party cloud service provider, which delivers computing resources such as servers and storage over the Internet. Customers or “cloud tenants” are able to purchase and provision compute, network and storage devices and services from the provider’s inventory of hardware, software and other supporting infrastructure.

Private Cloud: Where You Pay For The Privilege

The word has connotations that help define it. Anything private is always for those who can afford it. In this instance, it refers to cloud computing resources used exclusively by a single organization. This cloud can be physically located on a company’s on-site datacenter or hosted by a third-party service provider. What differentiates it from the public cloud, is that all its services and infrastructure are maintained on dedicated, private network and hardware infrastructure and used solely by one organization. Naturally, the greater control over data, services, security, and compliance comes with additional costs to provision and maintain.

Hybrid Cloud: A Little Bit Of This And That

This is simply a combination of a private and public cloud component that allows the sharing of applications and data between them. It is the most flexible approach because it offers businesses more deployment options; allowing them to choose the appropriate mix of on-premises and cloud. Customers can leverage services from multiple vendors with varying levels of cloud usage, which is another reason for its popularity.

Cloud Services: Your Building Blocks

These fall into three categories — Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (Saas) — each with its own set of benefits, challenges and models for provisioning and utilizing. They are often referred to as a cloud computing stack because they build on top of one another.

The lowest level is IaaS, which allows consumers to provision infrastructure such as servers, storage, networks and operating systems from a cloud provider on a pay-as-you-go basis. PaaS provides customers with an on-demand environment for developing, testing, delivering and managing software applications without the complexity of having to build and maintain the servers, networks, databases, and middleware.

SaaS — also sometimes referred to as ‘on-demand software’ — is a licensing and delivery model where software is centrally hosted and licensed on a subscription basis. It is the most confusing because it is often mistakenly referred to as cloud computing even though it is actually just the most common category of it. In the same category as SaaS, there is also Data-as-a-Service (DaaS), a model that involves offloading the risks and burdens of Data Management to a third-party cloud-based provider. This starts to make sense as the types and volume of data you retain and use becomes more complex and greater in size, which is when it becomes difficult and expensive to process, store and secure.

Subscription and SaaS: Not The Same Thing

Software-as-a-service allows customers to access software applications over the Internet, on demand, and on a per-seat or per-user basis. These applications and solutions are hosted by a third-party or software vendor and typically delivered online via a browser, mobile application or API. A customer pays not just for the software, but the required infrastructure, middleware, maintenance, and support that is required to run it. This right to use the service is sold as a subscription, for a given period of time.

The confusion arises when one assumes all subscription businesses are SaaS businesses, which is not the case because software vendors can also sell on-premises software with a term license (as opposed to a subscription) that does not include maintenance. In terms of costs, a subscription covers everything while a term license will incur separate maintenance and support fees for the use of the software.

One of the many things we love doing here at NexJ Systems Inc. is taking complex ideas and breaking them down into their component parts. We would love to know more about how you think of cloud computing or why you choose a particular kind of model.

Going back to the parable, none of the blind men are technically wrong, because they each interpret the elephant on the basis of their individual perceptions of the world. Similarly, in the rapidly expanding and evolving field of cloud computing, we often need to remind ourselves of the importance of communication and respect for different ideas and perspectives.