Cloud computing

Hello guys ,I think you all have definitely familiar with the term "Cloud computing".Thus have you ever thought ..what it is..??...umm ...if no...Than no problem ...here i am giving some knowledge about it from basic to professional level.
So what is cloud computing?
Before knowing about it lets know about what is cloud?
The term Cloud refers to a Network or Internet. In other words, we can say that Cloud is something, which is present at remote location. Cloud can provide services over network, i.e., on public networks or on private networks, i.e., WAN, LAN or VPN. Applications such as e-mail, web conferencing, customer relationship management (CRM),all run in cloud.
Ok now we get the idea of cloud ...so now what is cloud computing?
Well,Cloud Computing refers to manipulating, configuring, and accessing the applications online. It offers online data storage, infrastructure and application.

We need not to install a piece of software on our local PC and this is how the cloud computing overcomes platform dependency issues. Hence, the Cloud Computing is making our business application mobile and collaborative.

Now lets discuss about some basic concepts :
There are certain services and models working behind the scene making the cloud computing feasible and accessible to end users. Following are the working models for cloud computing:

• Deployment Models
• Service Models

 DEPLOYMENT MODELS
Deployment models define the type of access to the cloud, i.e., how the cloud is located? Cloud can have any of the four types of access: Public, Private, Hybrid and Community.

PUBLIC CLOUD 
The Public Cloud allows systems and services to be easily accessible to the general public. Public cloud may be less secure because of its openness, e.g., e-mail.
PRIVATE CLOUD 
The Private Cloud allows systems and services to be accessible within an organization. It offers increased security because of its private nature.
COMMUNITY CLOUD
The Community Cloud allows systems and services to be accessible by group of organizations. HYBRID CLOUD
The Hybrid Cloud is mixture of public and private cloud. However, the critical activities are performed using private cloud while the non-critical activities are performed using public cloud.
Hence it is about Deployment models .
Now discuss about Service models.
SERVICE MODELS
Service Models are the reference models on which the Cloud Computing is based. These can be categorized into three basic service models as listed below:
1.Infrastructure as a service(IaaS)
2.Platform as a Service(PaaS)
3.Software as a Service(SaaS)

There are many other service models all of which can take the form like XaaS, i.e., Anything as a Service. This can be Network as a Service, Business as a Service, Identity as a Service, Database as a Service or Strategy as a Service.
The Infrastructure as a Service (IaaS) is the most basic level of service. Each of the service models make use of the underlying service model, i.e., each inherits the security and management mechanism from the underlying model, as shown in the following diagram:

INFRASTRUCTURE AS A SERVICE (IAAS) 

IaaS provides access to fundamental resources such as physical machines, virtual machines, virtual storage, etc.

PLATFORM AS A SERVICE (PAAS)

 PaaS provides the runtime environment for applications, development & deployment tools, etc. SOFTWARE AS A SERVICE (SAAS) 

SaaS model allows to use software applications as a service to end users.

So Thats about cloud computing .Now lets discuss about its Benefits.

Benefits:

Cloud Computing has numerous advantages. Some of them are listed below:

• One can access applications as utilities,over the internet.
• Manipulate and configure the application online at any time
• not required to install a specific piece of software to access or manipulate cloud applications.
• Cloud Computing offers online development and deployment tools, programming runtime environment through Platform as a Service model.
• Cloud resources are available over the network in a manner that provides platform independent access to any type of clients
• Cloud Computing offers on-demand self-service. The resources can be used without interaction with cloud service provider
• Cloud Computing is highly cost effective because it operates at higher efficiencies with greater utilization. It just requires an Internet connection.
• Cloud Computing offers load balancing that makes it more reliable.

RISKS
As it has many benefits but there is some risks too in cloud computing although it is a great innovation .But nothing is perfect as we all know so here are some of its risks or disadvantages.

1. SECURITY & PRIVACY :It is the biggest concern about cloud computing. Since data management and infrastructure management in cloud is provided by third-party, it is always a risk to handover the sensitive information to such providers. Although the cloud computing vendors ensure more secure password protected accounts, any sign of security breach would result in loss of clients and businesses.
2. LOCK-IN:It is very difficult for the customers to switch from one Cloud Service Provider (CSP) to another. It results in dependency on a particular CSP for service.
3. ISOLATION FAILURE:This risk involves the failure of isolation mechanism that separates storage, memory, routing between the different tenants.
4. MANAGEMENT INTERFACE COMPROMISE:In case of public cloud provider, the customer management interfaces are accessible through the Internet.
5. INSECURE OR INCOMPLETE DATA DELETION:It is possible that the data requested for deletion may not get deleted. It happens either because extra copies of data are stored but are not available or disk destroyed also stores data from other tenants.