Cloud computing is transforming the way software is built and delivered. There is a shift from where we buy and control infrastructure or buy software to a new world where we consume everything as services. It is critical that managers and architects fully understand the pros and cons of cloud computing and the definitions of each cloud service model.
Cloud computing is about delivering computing services over the internet. The term cloud computing first appeared in 1996 and then cloud services became a commercial and profitable practice when Amazon released its product, Elastic Cloud Computer in 2006.
By 2008, Cloud services became very popular and many companies were switching from a traditional on-premises model to cloud computing service models.
To choose the right service model, it is important to understand what each service model is and what responsibilities the cloud service providers assume, and their responsibilities. The on-premises model refers to the traditional way of handling services and hardware in most companies. This involves having an IT department and hiring IT professionals; buying switches and servers, and find a place to house them; s power supply/electricity; install an Operating System (OS). All these require expertise and manpower for planning, configuration, and management. The traditional on-premises model gives us absolute control over our IT resources.
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Cloud Computing Model Essential Characteristics
• On-demand self-service
• Network access
• Resource pooling
• Location independence
• Rapid elasticity
• Measured service
Cloud Service Models
Software as a Service (SaaS)
With SaaS, you just connect to and use a cloud-based application over the internet because the Cloud Service Provider manages all aspects of the service applications hence, no worry about setting up physical hardware, installing OS, virtualization, setting up a network, installing and maintaining middleware, runtime, and applications, as all these are taken care by the CSP. All the hardware and software are maintained and managed by the CSP.
We simply access the application we want to you over the internet and as a pay-as-you-go model, you pay based on the usage. The software runs at the CSP’s data center on their physical servers.
This model can be used by small, medium, and large organizations. Examples of SaaS are Gmail, Netflix, Office 365, Dropbox, GoogleDrive, Google mail, etc. There are varieties of SaaS applications such as
• Customer Relationship Management (CRM)
• Financial Management
• Sales Management
• Human Resource Management (HRM)
• Storage etc.
Platform as a Service (PaaS)
Having explained IaaS, It will be easy to understand PaaS as this boils down to what your organization manages versus what CSPs manage. With IaaS, the CSP manages the infrastructure, that is networking, servers, storage, and virtualization while your company manages everything else like the Operating System, middleware, runtime, data, and applications. When compared with IaaS, PaaS provides an even higher level of abstraction. You can think of it as a layer on top of IaaS. It shifts more responsibility to the CSP. All your organization manage is just your business applications or services, and the underlying data while the rest like runtime, middleware, Operating System(OS), virtualization, servers, storage, and networking are managed by the CSP. Hence, this gives you more time to concentrate on other important areas of your business.
Examples are AWS Elastic Beanstalk, Oracle Cloud Platform, Microsoft Azure, Google App Engine
Infrastructure as a Service (IaaS)
If you are not using the cloud you manage everything on-premise, meaning your organization is responsible for managing pretty much everything such as networking, storage, servers, data centers, making sure power supply, cooling systems, etc are in place. You will also ensure the installation and configuration of your Virtualization software and the Operating Systems, and runtime components that your team needs. In essence, your organization is responsible for managing everything.
With IaaS, you rent or lease IT infrastructure from a CSP like Amazon Web Services and Microsoft Azure, Google Cloud, etc. So there is no need for your organization to procure and manage the infrastructure, as it is the CSP that is responsible for procuring physical servers, storage, and hardware, setting up networks, the CSP manages and secures the data center. In other words, the CSP hosts the infrastructure and the data center while you as the customer provide this infrastructure on-demand over the internet or through a virtual private connection.
For the duration that you use the infrastructure, you pay a fee and you are only charged based on the number of machines and resources that are actually being used. Your own job is to manage your Operating Systems, data, runtime, middleware, and applications. This means that you have better control and you can install any Operating System of your choice like Windows or Linux etc.
Cloud Deployment Models
As the name implies, a Private cloud is private to a single organization. In other words, the resources and services are used exclusively by one business or organization. The private cloud is physically in the organization’s onsite data center or hosted by a third-party Cloud Service Provider. In a private cloud, it is very easy to customize the hardware and software to meet your organization’s specific IT requirements. This is because your organization owns everything that is, the hardware, software, and network so you have complete control and can change anything in any way you want to meet your organization’s requirements. Private Clouds are often used by any medium or large organization with business-critical operations that wants complete control over their cloud environment.
Being the most common type of cloud, it is easy for anyone that is, an individual or an organization to start using public cloud resources and services. You don’t have to worry about buying the hardware, maintenance as all the infrastructure such as the physical servers, storage, and networking, etc, are purchased and owned by the Cloud Service Provider. It is the CSP that setup and maintains it. Microsoft Azure, Amazon Web Services, Google Cloud, Oracle Cloud, etc, are examples of a public cloud.
To access public cloud resources, we need an internet connection hence to manage the cloud services and resources, the CSP creates a web portal and we pay for the services and resources that we use. It is a pay-as-you-go model hence, you only pay for what you use.
In this cloud model, organizations share resources with other organizations and this is called Multi-tenancy- in which your organization’s data is stored with other organizations data on the same storage device.
A hybrid cloud, like the name implies, is a combination of both the private and public cloud. These unique entities work together to meet our organization’s requirements, that is, it offers the best of both worlds. For example, we can use the private cloud model for sensitive business operations and then use the public cloud model for less sensitive business operations.