Cloud Computing: Deployment Models

Deployment Models of Cloud Computing:

Cloud Computing is a growing trend that offers an innovative way to deliver software, data storage and computing services. Cloud services can be deployed in different ways, depending on the organizational structure and the provisioning location. Four deployment models are usually distinguished, namely public, private, community and hybrid cloud service usage.

Public Cloud:-

The public cloud deployment model represents true cloud hosting. In this deployment model, services and infrastructure are provided to various clients. Google is an example of a public cloud. This service can be provided by a vendor free of charge or on the basis of a pay-per-user license policy.
This model is best suited for business requirements wherein it is required to manage load spikes, host SaaS applications, utilize interim infrastructure for developing and testing applications, and manage applications which are consumed by many users that would otherwise require large investment in infrastructure from businesses.
This model helps to reduce capital expenditure and bring down operational IT costs.

Private Cloud:- 

Private clouds give users immediate access to computing resources hosted within an organization's infrastructure and the resources are dedicated solely for that organization's use. Users self-provision and scale collections of resources drawn from the private cloud, typically via web service interface, just as with a public cloud. However, because it is deployed within the organization's existing data center—and behind the organization's firewall—a private cloud is subject to the organization's physical, electronic, and procedural security measures and thus offers a higher degree of security over sensitive code and data.
With private cloud, the performance of physical hardware can be controlled and maintained by the organization, and can thus markedly improve data center efficiency while reducing operational expense.

The Hybrid Cloud:-

The hybrid cloud computing model employs aspects of all of the other cloud models and it is the most common method of cloud deployment within a large organization. A company may use internal resources in a private cloud maintain total control over its proprietary data. It can then use a public cloud storage provider for backing up less sensitive information. At the same time, it might share computing resources with other organizations that have similar needs. By combining the advantages of the other models , the hybrid model offers organizations the most flexibility. 

Community Cloud:-

The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises. 

 

Cloud Computing: Service Model of Cloud Computing

What are the Service Model in Cloud Computing?

Service delivery in Cloud Computing comprises three different service models, namely Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), and Software-as-a-Service (SaaS). The three service models or layer are completed by an end user layer that encapsulates the end user perspective on cloud services.

If a cloud user accesses services on the infrastructure layer, for instance, he can run his own applications on the resources of a cloud infrastructure and remain responsible for the support, maintenance, and security of these applications himself. If he accesses a service on the application layer, these tasks are normally taken care of by the cloud service provider.

1. Software as Service (SaaS):- Software-as-a-Service provides complete applications to a cloud’s end user. It is mainly accessed through a web portal and service oriented architectures based on web service technologies. Credit card or bank account details must be provided to enable the fees for the use of the services to be billed.
The services on the application layer can be seen as an extension of the ASP (application service provider) model, in which an application is run, maintained, and supported by a service vendor. The main differences between the services on the application layer and the classic ASP model are the encapsulation of the application as a service, the dynamic procurement, and billing by units of consumption (pay as you go). However, both models pursue the goal of focusing on core competencies by outsourcing applications.

                   

2. Platform as a Service:- PaaS comprises the environment for developing and provisioning cloud applications. The principal users of this layer are developers seeking to develop and run a cloud application for a particular platform. They are supported by the platform operators with an open or proprietary language, a set of essential basic services to facilitate communication, monitoring, or service billing, and various other components, for instance to facilitate startup or ensure an application’s scalability and/or elasticity (see figure 3). Distributing the application to the underlying infrastructure is normally the responsibility of the cloud platform operator. The services offered on a cloud platform tend to represent a compromise between complexity and flexibility that allows applications to be implemented quickly and loaded in the cloud without much configuration. Restrictions regarding the programming languages supported, the programming model, the ability to access resources, and persistency are possible downsides.

The services on the infrastructure layer are used to access essential IT resources that are combined under the heading Infrastructure-as-a-Service (IaaS). These essential IT resources include services linked to computing resources, data storage resources, and the communications channel. They enable existing applications to be provisioned on cloud resources and new services implemented on the higher layers.
Physical resources are abstracted by virtualization, which means they can then be shared by several operating systems and end user environments on the virtual resources – ideally, without any mutual interference. These virtualized resources usually comprise CPU and RAM, data storage resources (elastic block store and databases), and network resources as displayed below.

Infrastructure-as-a-Service (IaaS) Stack

Cloud Computing : Intoduction of Cloud Computing

What is Cloud Computing?
According to NIST Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.


Essential Characteristics of Cloud Computing

The five characteristics of the cloud computing model were originally defined by the National Institute of Standards and Technologies (NIST) and have since been refined by a number of experts. The model has been published many times before, but if you’re like me you need to see something several times before you really internalise it.

1.On Demand Self Service:-

 You can quickly and easily configure the computing resource you need all by yourself, without filling out forms or emailing the service provider. A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service provider.

2. Board Network Access:-

You can access these resources from anywhere you can access the Internet, and you can access them from a browser, from a desktop with applications designed to work with them or from mobile devices.

One of the most popular application models (such as iPhone apps) is a mobile application that communicates with a cloud-based back end.

3. Resource Pooling:- 
The provider’s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or data-center). Examples of resources include storage, processing, memory, and network bandwidth.

4. Rapid elasticity:-

 You can grow and shrink your capacity (processing power, storage, network) very quickly, in minutes or hours. Self-service and resource pooling are what make rapid elasticity possible. Triggered by a customer request, the service provider can automatically allocate more or less resources from the available pool.

   

5. Measured service:-
 Also described as subscription-based, measured service means that the resources you’re using are metered and reported back to you. You pay for only the resources you need, so you don’t waste processing power like you do when you have to buy it on a server-by-server basis.

Frankly, I recommend that you memorise this list; you’ll have the vague term “cloud” thrown at you many times in the future, and understanding these five characteristics will help you judge whether the latest offering you’re being shown is really cloud computing. And as an added plus, you’ll be able to finally explain cloud computing to your friends and relatives.