What is cloud computing?

by Alexander Weiß

There are many different answers to the question “What is a cloud?” or, more specifically, “What is cloud computing?”. Some of the answers have a very narrow point of view. In this post, I’ll give you a short overview of the different types of cloud computing.

In recent years, the term “cloud” has gotten more and more popular. Today, nearly everything is a cloud. But this term encompasses very different service models. The National Institute of Standards & Technology defined the different service models in their paper “The NIST Definition of Cloud Computing”. Based on this paper, I’ll give a short summary of what cloud computing is and which different kinds of clouds exist.

Fundamental elements of cloud computing are:

  • Self-service: The user can order and configure the product without any need for human interaction by the service provider.
  • Measured service: The user is informed about how much capacity she’s using, and the resource utilization is transparent for the service provider and the consumer.
  • Elasticity: The service provider can upgrade the service at any time to provide access to more computational power or storage space. The resources seem to be unlimited and can be purchased in any quantity and at any time.
  • Resource pooling: The provider’s computing, storage, and network resources are pooled together and the user has no information about the composition of the pool. The consumer usually cannot influence where the resources for his service are exactly located. Some providers let the user choose where his service is provided on a higher level of abstraction.
  • Broad network access: The service is available over a network and requires thin or thick clients.
What is cloud computing

What is cloud computing

The advantages of cloud computing are that the user can immediately, and without a huge budget, access enormous amounts of CPU and storage capacity. As fast as she can access these services, she can terminate them. She only has to pay for the service when she is using the service, thus saving him a lot of money. Whenever she needs more power, she can easily add more processing power to his subscription, and then get rid of it just as easily.

Now that you’ve seen some general explanations of what cloud computing is, I want to give a short overview of the differences of cloud computing. The first difference is caused by security demands and results in different deployment models. The Private Cloud can fulfill every security demand, whereas Virtual Private Clouds, Public Clouds, Communities Cloud and Hybrid Clouds can’t fulfill every security demand.

Private Cloud

  • A limited set of users who access unlimited numbers of services
  • Users know where their data is hosted and can fulfill legal and compliance aspects
  • Heavy use of virtualization techniques
  • Automatization and Self-Service Provisioning features
  • Cloud is only used by a single organization
  • Personal and structural adjustments are necessary

Virtual Private Cloud

To avoid the personal and structural adjustments of the private cloud, many companies implement a virtual private cloud. The main difference is that the virtual private cloud is not hosted on premise, and it is not managed by the organization’s staff. In this context, virtual means that the privacy is just virtual because the service is outsourced.

Public Cloud

  • Unlimited number of users who access clearly defined services
  • Owned, managed, and operated by a single organization
  • Exists on the premises of the cloud provider

Community Cloud

  • A mixture of the characteristics of a private and a public cloud
  • Not open to the public but serves more than one organization
  • Services are suited to the needs of a community or a specific set of organizations that share a common interest

Hybrid Cloud

  • A combination of a private cloud and a public cloud, whereas the private cloud handles the core processes of the business and the sensitive data and the public cloud is used for services that are not critical for the business
  • The two entities are bound together to allow data and application portability
  • Option to insource the cloud should always be considered

The second main difference in cloud computing is the service model. There are three basic models: IaaS, PaaS and SaaS.

IaaS (Infrastructure as a Service)

  • Offers place in a data center and takes care of the USV, cooling, and network
  • Provider delivers processing, storage, and network resources
  • Consumer can deploy and run arbitrary software
  • Consumer has no control over the underlying hardware but can control the software layer starting with the operating system

PaaS (Platform as a Service)

  • Integrated runtime and development environment where the user can deploy his own applications
  • Benefits are usually available over the Internet
  • User has control over the deployed applications and some of the parameters of the application’s hosting environment
  • Only the supplier profits from virtualization

SaaS (Software as a Service)

  • Customer pays for using an application that is running in the provider’s cloud infrastructure
  • User only has control over the application settings
  • Only the supplier profits from virtualization

As you can see, the term “cloud” is just a generic term. The concepts behind cloud computing are so diverse that it is obvious why everybody can claim that he or she is “cloud ready” or “cloud based.” It is a direct result of the desire to participate and profit from the cloud hype, but it also is the truth.

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