The past decade has witnessed a dramatic change in the way organizations handle their computing needs. In the 1990s and early 2000s, most enterprises ran their applications on servers that they owned and maintained in their own data centers. But today, cloud computing has come to the forefront.
In fact, the RightScale 2017 Cloud Computing Survey found that 95 percent of the organizations surveyed were using at least one cloud, and 85 percent were using multiple clouds. The average enterprise now runs the majority of its workloads in the cloud: 32 percent of them in the public cloud and 43 percent in a private cloud.
As public, private and hybrid cloud computing has become the norm, businesses have begun to change the ways they think and talk about software and hardware. Now instead of buying an individual application or owning their own IT infrastructure, they often consume computing resources as a cloud service instead.
Webopedia defines cloud services as "any service made available to users on demand via the Internet from a cloud computing provider's servers as opposed to being provided from a company's own on-premises servers." Instead of paying a one-time fee to purchase software or hardware outright, organizations purchase cloud services through a subscription. The fees are tied to their usage of the computing resources, and it is easy to scale up or down as they need more or fewer resources.
Most people use cloud services every day — although they may not realize it. If you have Web-based email like Gmail or Outlook.com, that is a cloud service. If you use online office productivity tools like Office 365 or Google Docs, that is a cloud service. If you use a file sharing service like Dropbox or Box, online storage like iCloud or Amazon Drive, online backup like Carbonite or online software like Salesforce, those are all cloud services.
These days, cloud services have become so commonplace that some laptops, such as Chromebooks, are designed to use cloud services almost exclusively, with nearly no software installed on the computer's hard drive other than the operating system.
Some people also use the term “cloud services” to refer to professional services related to the cloud. For example, vendors might offer “cloud services” that help organizations migrate to the cloud, integrate various cloud services, manage cloud workloads or secure their clouds. However, this article will focus on the first definition rather than those sorts of professional services.
In order to use a cloud service you need two things: 1) a device with an Internet browser and 2) a Web connection. With a cloud service, your data isn't stored on your PC or mobile device, it's stored in the service provider's data center. That means you can pick up where you left off even if you switch devices. Similarly, the applications that you are running aren't saved on your device's hard drive; instead, they are running on the servers in the service provider's data center. Essentially, you are using the computing power of a server that may be hundreds or thousands of miles away, and you are accessing it via the Web.
However, just because you access something via the Web doesn't necessarily make it a cloud service. According to the National Institute of Standards and Technology (NIST), a service has to have five characteristics in order to qualify as a cloud service:
Source: The Open Group
Organizations choose to use cloud services because they offer a number of benefits that aren’t available with other types of IT environments:
Cloud services vendors often describe their offerings with a label that ends in the words "as a service." For example, they might offer backup as a service, storage as a service, database as a service or even IT as a service. However, all of these types of cloud services generally fit into one of three major categories: software as a service, platform as a service or infrastructure as a service.
In the software as a service (SaaS) model, a vendor hosts an application in its own servers, and end users access the software via a browser. Users generally pay a subscription fee for the SaaS — often on a monthly or annual basis.
Because it is delivered via the Web, a SaaS offering can be accessed from anywhere, making it a good option for companies with mobile workers. In addition, the vendor does all the work of maintaining and updating the software as well as the hardware it runs on, and that makes SaaS attractive to companies with small IT teams. SaaS also enables companies to get started quickly and scale easily, which appeals to startups and growing companies.
On the negative side, organizations often don’t have as much opportunity to customize SaaS as with on-premise software. In addition, they often face difficulties integrating their SaaS data with their other applications, and it can be tough to switch vendors after committing to one SaaS supplier. SaaS may also not be a good choice for organizations with stringent compliance requirements or those with security concerns.
The world's largest SaaS vendors include Salesforce.com, Microsoft, Intuit, Google, ADP, SAP, Oracle, IBM, Cisco and Adobe.
With infrastructure as a service (IaaS), customers rent access to servers, storage, networking and other hardware that they use to run their applications. The cloud services vendor generally isn’t supplying software, other than perhaps the operating system.
IaaS is a good choice for companies that are developing their own applications, and it is very popular with development teams that need a quick way to set up dev and test environments. It’s also a good option for organizations seeking agility and scalability. Other organizations look to IaaS when they want to keep costs low or when they want to convert some capital expenses into operational expenses.
However, it is helpful to have some cloud expertise when using an IaaS, and it might not be as good an option for organizations that have very small IT teams. Organizations should also be careful to make sure that their IaaS will meet their security and compliance needs.
Amazon Web Services is the leading IaaS vendor. Others include Microsoft Azure, Google Cloud, IBM SoftLayer and VMware vCloud Air.
The platform as a service (PaaS) model offers some of the features of SaaS and some of the features of IaaS. While PaaS vendors don’t provide software for end users, they do provide all of the infrastructure and tools that developers might need to create, deploy, manage and secure their own applications. For example, a PaaS designed for Web developers might bundle together an operating system, Web server, content management system, database and other tools along with the compute power and storage necessary for running a website.
Vendors generally market PaaSes to developers, who like them because they make it much faster and easier to get started on a development project. A PaaS offering might not be a good option for smaller organizations without development teams or for organizations with strict compliance and security needs.
The list of leading PaaS vendors is very similar to the list of IaaS vendors, and it includes Amazon Web Services, Microsoft Azure, IBM Bluemix, Google App Engine, Salesforce App Cloud, Red Hat OpenShift, Cloud Foundry and Heroku.