A Comprehensive Introduction to Cloud Computing


I’m aware that there many cloud computing introductory articles or papers out there, so why am I writing another one? As this my first article at A Cloudy Place, I’d like to start at the beginning and take a new approach to explain the cloud.

Would you rather buy or rent a car?

The analogy that I will be using is very simple and I believe some readers have probably run into it at some point. Have you ever considered buying or renting a car?

Buying or Renting Cloud Computing

Buy Your Own Car

Buying a car is a big investment, and there are a lot of important decisions to take into account. Some people like all the different options, and others don’t want to bother with thousands of decisions.  When buying a car you have full control over everything, its make and model, cost, interior, etc. Additionally, you’ve got to work about taxes, insurance, inspections, and all sorts of maintenance, you’ve got the control, but it comes with a hassle.

Renting a Car

Then how about renting a car? You have fewer and simpler decisions to make. You just need to select a car from what’s available, and you can switch your car if something comes up.

Rent when you need; pay when you use. You don’t have to worry about maintenance costs, tax, and insurance since they are included in your rental fee. On the other hand, there are obviously some disadvantages. You’re limited by what’s available from the rental vendor, you may not be allowed to customize the car, and the car is not dedicated to you all the time.

Translating the Analogy to Cloud Computing

This simple real life analogy is easily translatable to Cloud Computing.

Buying your own car is similar to setting up your own on-premise data center. You have the flexibility to customize whatever you like, starting from physical infrastructure, the security system, hardware and software, etc. However, you also have to invest a lot of money upfront. And also, you will also need to manage it later when it’s operating.

On the other hand, instead of building your own data center, you can rent computation power and storage from the cloud provider. You can scale in and out when necessary. Just pay when you use. No specific commitment takes place. You can start and stop anytime.

Characteristics of Cloud Computing

This summarizes the characteristics of cloud computing.

  • On-demand

Resources should be always available when you need them, and you have control over turning them on or off to ensure there’s no lack of resource or wastage happen.

  • Scalable

You should be able to scale (increase or decrease the resource) when necessary. The cloud providers should have sufficient capacity to meet customer’s needs.

  • Multi-tenant

Sometimes you may be sharing the same resource (e.g. hardware) with another tenant. But of course, this is transparent to the customer. Cloud provider shall responsible the security aspect, ensuring that one tenant won’t be able to access other’s data.

  • Self-service computation and storage resource

Related processes including: billing, resource provisioning, and deployment should be self-service and automated, involving much less manual processing. If a machine where our service is hosted fails, the cloud provider should be able to failover our service immediately.

  • Reliability

Cloud provider should be able to provide customer reliability service, committing to uptimes of their service.

  • Utility-based subscription

You will pay the cloud provider as a utility based subscription, just like paying your electricity bill – without any upfront investment.

Cloud Computing Service Model

Cloud Computing consists of several type of service models.

  • On-premise Environment
    As you can see, for the first stack from left, you will need to take care of everything from networking all the way up to applications. This is typically what many of us are doing today.
  • IaaS (Infrastructure as a Service)
    IaaS helps you to take care of some of the components, starting from networking to provisioning the OS. But you are responsible for the middleware, runtime, data, and application. Sometimes IaaS vendors will just provide the OS but will not manage updates or patches for you. You basically just rent the virtual machine (VM) with the preferred OS installed. They won’t care what you do with the VM.
    Example of IaaS market players: Amazon Web Service, Rackspace, and VMware vCloud.
  • PaaS (Platform as a Service)
    Paas is one level up from IaaS, where cloud providers not only take care of the components that IaaS does; but also manage the platform-level components like middleware and runtime. Middleware such as applications / web server (IIS, JBoss, Tomcat, etc.) and runtime (.NET Framework, Java runtime) will be pre-installed. As a customer, you just need to focus on managing application and data.
    Example of PaaS market player: Google AppEngine, Windows Azure Platform, andforce.com.
  • SaaS (Software as a Service)
    SaaS is probably the most common one as we may have been using it, unaware that they are actually cloud services. SaaS takes care of all the stacks from networking to application level. You don’t even manage the application and data storage. All you need to do is to use the system.
    Example of SaaS market player: GMail, Office 365, and Google Docs.

Cloud Computing Deployment Model

There are three main cloud deployment models, each on with its own set of customers it’s targeting.

  • Public Cloud
    Public cloud provider refers to the cloud platform that targets any types of customers, regardless of whether they’re an independent consumer, enterprise, or even public sector. Normally, public cloud providers are considered prominent players which have invested huge amount of capital. Windows Azure Platform by Microsoft, AWS by Amazon, AppEngine and Gmail by Google, etc. are all examples of public cloud services. Customers who possess sensitive data and application normally do not feel comfortable using public cloud due to privacy, policy, and security concerns. Remember, for public cloud, the application and data will be stored in the provider’s data center.
  • Private Cloud
    Private cloud is infrastructure that’s hosted internally, targeting specific customers or sometimes exclusively within an organization. Setting up a private cloud is normally more affordable when compared to a public cloud. As the matter of fact, there are many organizations who have implemented their own private cloud system with product offering from vendors such as IBM, HP, Microsoft, and so on. Customers who possess sensitive data and application feel more comfortable going with this approach since the data and application are hosted privately.
  • Hybrid Cloud
    Hybrid cloud is the combination of public and private clouds, or sometimes on-premise services. Customers who look into this solution generally want to utilize the scalability and cost-competitiveness that public cloud providers offer, but also want to retain their sensitive data on-premise or in a private cloud. With the benefits derived from both deployment models, the hybrid model solution has become more popular nowadays.

I sincerely hope that, this article would be helpful to you. In my next article, I’ll discuss more about the comparison between IaaS and PaaS.

This post was also published at A Cloud Place blog.

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1 Response to A Comprehensive Introduction to Cloud Computing

  1. Pingback: Moving Applications to the Cloud: Part 2 – A Scenario-Based Example | Wely's Cloud Journey...

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