Deployment Models

Deploying cloud computing can differ depending on requirements, and the following four deployment models have been identified, each with specific characteristics that support the needs of the services and users of the clouds in particular ways .

• Private Cloud — The cloud infrastructure has been deployed, and is maintained and operated for a specific organization. The operation may be in-house or with a third party on the premises.
• Community Cloud — The cloud infrastructure is shared among a number of organizations with similar interests and requirements. This may help limit the capital expenditure costs for its establishment as the costs are shared among the organizations. The operation may be in-house or with a third party on the premises.
• Public Cloud — The cloud infrastructure is available to the public on a commercial basis by a cloud service provider. This enables a consumer to develop and deploy a service in the cloud with very little financial outlay compared to the capital expenditure requirements normally associated with other deployment options.
• Hybrid Cloud — The cloud infrastructure consists of a number of clouds of any type, but the clouds have the ability through their interfaces to allow data and/or applications to be moved from one cloud to another. This can be a combination of private and public clouds that support the requirement to retain some data in an organization, and also the need to offer services in the cloud.

Layers of Cloud Computing

Cloud Infrastructure as a Service (IaaS) -  It is the delivery of computer infrastructure( typically a platform virtualization environment) as a service .The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components (e.g., host firewalls).

Cloud Software as a Service (SaaS) - It is a model of software deployment whereby the provider licenses an application to the customers for use as a service on demand. The capability provided to the consumer is to use the provider’s applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., web based email). The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user specific application configuration settings.

Cloud Platform as a Service (PaaS) -  It is the delivery of computing platform and solution stack as a service . The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations.

Definition of Cloud Computing - Its Essential Features

Origin of Cloud Computing

         Comes from the early days of the Internet where we drew the network as a cloud… we didn’t care where the messages went… the cloud hid it from us” – Kevin Marks, Google. 

• First cloud around networking (TCP/IP abstraction)
• Second cloud around documents (WWW data abstraction)

         The emerging cloud abstracts infrastructure complexities of servers, applications, data, and heterogeneous platforms.

Cloud computing is a model for enabling 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.
This cloud model promotes availability and is composed of five essential characteristics, three service models,and four deployment models.

This cloud model promotes availability and is composed of five essential characteristics, three service models,and four deployment models.

Five essential characterstics

*   On-demand Self Service. A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service’s provider.

*  Broad Network Access. Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, laptops, and PDAs). 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, network bandwidth, and virtual machines.

*  Rapid Elasticity. Capabilities can be rapidly and elastically provisioned, in some cases automatically, to quickly scale out, and rapidly released to quickly scale in. To the consumer, the capabilities availablefor provisioning often appear to be unlimited and can be purchased in any quantity at any time.

*  Measured Service. Cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported providing transparency for both the provider and consumer of the utilized service.

A Walk In The Cloud

The term Cloud Computing is relatively new, and some say it is no different than “Utility Computing,” the idea that the internet is the electric company. The image of a cloud comes from engineers and technicians who use a fluffy cumulus cloud in wiring diagrams to designate a network built and maintained outside of an organization. The faster internet connections have become – 10mbps, 20 mbps, 40 mbps, the more applications and storage have moved to the Cloud and out of internal servers and PCs. In fact, all processing power, applications and storage a communications professional might need today are available already through Cloud Computing.

Cloud Computing requires high-speed broadband service and enormous data storage, but current predictions are that nothing will stop the internet from reaching petabyte size and speed. That is a thousand trillion bytes of storage, an unimaginable size, and equally astonishing speed. This means millions of people can download multi-billion-byte, high- definition, feature-length movies at the same time without slowing down or straining the internet. There are serious capacity and economic issues to achieving this scale, but internet service providers are moving to solve them. Some countries have already achieved extraordinary speed and volume such as Korea, Japan and Australia.

Figure, adapted from Voas and Zhang (2009), shows six phases of computing paradigms, from dummy terminals/mainframes, to PCs, networking computing, to grid and cloud computing.

In phase 1, many users shared powerful mainframes using dummy terminals.

In phase 2, stand-alone PCs became powerful enough to meet the majority of users’ needs.

In phase 3, PCs, laptops, and servers were connected together through local networks to share resources and increase performance. 

In phase 4, local networks were connected to other local networks forming a global network such as the Internet to utilize remote applications and resources.
In phase 5, grid computing provided shared computing power and storage through a distributed computing.