Software as a Service (SaaS)
When we use Software as a Service product, it usually doesn’t feel as if we’re actually using a remote server or logging into a SaaS provider’s system. That’s because SaaS applications are designed to look and feel just like the software on our computers and devices. In fact, millions of people around the world are using SaaS products today without realizing that they’re cloud-based!
SaaS providers such as Zimbra, Gmail, and SalesForce.com, to name a few, work hard to make their products easy to use. They provide their customers with fully-functioning, on-demand software over the web. And because the software doesn’t need to be installed locally on customers’ machines, there’s no need for them to worry about the installation and configuration of these applications. Like utility power, the software just works - anywhere, any time!
There’s a catch though. For SaaS providers to serve as many different groups of people as possible, they have to balance their individual customers’ desire for flexibility with the need for general usability by all their users. SaaS applications, therefore, tend to be very uniform and standardized, meaning that users usually cannot customize the way the software works.
However, users are sometimes able to customize how the software looks and feels. Best of all, they don’t need to manage or maintain any aspect of the system, not even the backup and recovery of their own data.
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It’s easy to see the benefits of SaaS in corporate settings, where a single copy of a SaaS application is used on many computers. Tasks such as file-sharing and software updating can be done much more efficiently, freeing up time and resources for use elsewhere.
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Platform as a Service (PaaS)
Some users require more hands-on control of their cloud computing environment than SaaS can provide – for example, web-hosting companies and developers. Often, Platform as a Service gives users the development tools, application sets, and base operating systems they need to be productive with this higher level of control. Included in PaaS is the ability to upload content to an application server where new apps can be created and run.
You can’t access the underlying operating system, though. Full remote control of the PaaS server is also off-limits. So, although you have the tools and the flexibility you need to develop your applications and customize how they work, you still must rely on your PaaS provider to apply operating system and service patches.
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The good news is that, as PaaS providers typically check updates to their software very carefully, PaaS environments are usually very stable. The not-so-good news is that those updates may take a while to arrive because providers have to check that each and every program that they supply has all the programs it depends on to function properly. (This process is called “dependency-checking”.) For obvious reasons, this complex requirement can take time.
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Infrastructure as a Service (IaaS)
With Infrastructure as a Service, you have even more control when compared to SaaS or PaaS as you’re provided with a dedicated virtual machine and then get to install desired operating systems, services, and software that your organization needs. You have complete control over the virtual machine – configuration, updates, everything. Instead of tying up valuable resources with expensive hardware (including the technicians, facilities, and software needed to operate and maintain it), you outsource your hardware requirements – i.e., pay an IaaS provider to be responsible for them.
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Because no two organizations are given the same virtual machine to share, IaaS provides better security and better separation of different organizations’ memory, storage, routing, etc. (The techniques used to achieve this separation are called “isolation”.)
There are many forms of IaaS cloud computing, as we’ll see shortly. What the various forms all have in common is that in each one, the user is presented with an operating system. With the simplest form of IaaS, where the user is provided with a virtualized server that they have full control over, a server operating system (an advanced type of operating system specially-designed to run on servers) is included.
Other forms of Infrastructure as a Service are Desktop as a Service (DaaS), Disaster Recovery as a Service (DRaaS), and Containers as a Service (CaaS). With DaaS, you access a virtual desktop and applications from the device and location of your choice, while your cloud provider handles storage, security, backups, and upgrades from its data center. DRaaS provides a complete virtual backup of an organization’s system, plus the automatic switching to that backup, in the event of a system failure. (In some places, you’ll see DRaaS referred to as Recovery as a Service – RaaS).
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CaaS provides the containers, automation processes (collectively known as “orchestration”), and computing resources needed for container-based virtualization - either on-premises or via the cloud.
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In addition to the IaaS desktop and disaster recovery environments, there are several others, including:
- The IaaS production environment is for when a user needs to run live applications.
- The IaaS replication environment is for when a user needs high availability and therefore has a replicated (i.e., copied) environment.
- The IaaS development environment is for when a user or developer needs a test environment for a short period of time.
VMware allows its users to deploy (i.e., use) and manage resources on multiple vendor cloud platforms, different vendor hypervisors, and different vendor hardware. The flexibility of its products and processes can be seen by how widely they are used on popular cloud platforms such as Amazon Web Services (AWS), Microsoft Azure, Red Hat, and OpenStack, to name just a few.