CLOUD COMPUTING – An Overview
Resource sharing in a pure plug and play model that dramatically simplifies infrastructure
planning is the promise of „cloud computing‟. The two key advantages of this model are easeof-use and cost-effectiveness. Though there remain questions on aspects such as security
and vendor lock-in, the benefits this model offers are many. This paper explores some of the
basics of cloud computing with the aim of introducing aspects such as:
Realities and risks of the model
Components in the model
Characteristics and Usage of the model
The paper aims to provide a means of understanding the model and exploring options
available for complementing your technology ...view middle of the document...
1. Software as a Service (SaaS): In this model, a complete application is offered to the customer,
as a service on demand. A single instance of the service runs on the cloud & multiple end users
are serviced. On the customers‟ side, there is no need for upfront investment in servers or
software licenses, while for the provider, the costs are lowered, since only a single application
needs to be hosted & maintained. Today SaaS is offered by companies such as Google,
Salesforce, Microsoft, Zoho, etc.
2. Platform as a Service (Paas): Here, a layer of software, or development environment is
encapsulated & offered as a service, upon which other higher levels of service can be built. The
customer has the freedom to build his own applications, which run on the provider‟s
infrastructure. To meet manageability and scalability requirements of the applications, PaaS
providers offer a predefined combination of OS and application servers, such as LAMP platform
(Linux, Apache, MySql and PHP), restricted J2EE, Ruby etc. Google‟s App Engine, Force.com,
etc are some of the popular PaaS examples.
3. Infrastructure as a Service (Iaas): IaaS provides basic storage and computing capabilities as
standardized services over the network. Servers, storage systems, networking equipment, data
centre space etc. are pooled and made available to handle workloads. The customer would
typically deploy his own software on the infrastructure. Some common examples are Amazon,
GoGrid, 3 Tera, etc.
Figure 2: Cloud models
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Understanding Public and Private Clouds
Enterprises can choose to deploy applications on Public, Private or Hybrid clouds. Cloud
Integrators can play a vital part in determining the right cloud path for each organization.
Public clouds are owned and operated by third parties; they deliver superior economies of
scale to customers, as the infrastructure costs are spread among a mix of users, giving each
individual client an attractive low-cost, “Pay-as-you-go” model. All customers share the
same infrastructure pool with limited configuration, security protections, and availability
variances. These are managed and supported by the cloud provider. One of the advantages
of a Public cloud is that they may be larger than an enterprises cloud, thus providing the
ability to scale seamlessly, on demand.
Private clouds are built exclusively for a single enterprise. They aim to address concerns on
data security and offer greater control, which is typically lacking in a public cloud. There are
two variations to a private cloud:
On-premise Private Cloud: On-premise private clouds, also known as internal
clouds are hosted within one‟s own data center. This model provides a more
standardized process and protection, but is limited in aspects of size and scalability.
IT departments would also need to incur the capital and operational costs for the
physical resources. This is best suited for applications which require...