Cloud Computing

• In cloud computing, there's asignificant workload shift from local machine to  cloud. The local machine would only have to load one applicationwhich allow to  log into remote machineswhich hosts all the  programs the user  would need for  his job.
• The consumer may no longer be required to pay for a PC, or purchase specific software, leading to lower upfront, capital and operating expenses.
• End users may not need to care about how servers and networks are maintained, and can access multiple servers anywhere on the globe.
• Remote machines owned by another company  would run everythingfrom e-mail  to word processing. It's called cloud computing.

Characteristics of Cloud Computing

• Elasticity and Scalability: It gives us            the      ability      to      expand resourcesaccording to the specific requirement.
• Pay-per-Use: We payfor cloud services only when we usethem.

and      reduce

• On-demand: With cloud services there is no need to have dedicated resources waiting to be used.
• Resiliency: It can completely isolate the failure ofserver and storage resources from cloud users and Work can be migrated to a different server.

• Multi Tenancy: Public cloud service providers often host the multiple userswithin the same infrastructure.
• Workload Movement: Service providers can migrate workloads servers. This migration can result in cost efficiency.

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Advantages of Cloud Computing

• Accessibility: Data and applications can be accesses anytime, anywhere.
• Globalize the workforce: Staff can work from anywhere in world.
• Economies of scale: Since Service provider invest in large infrastructure, even with fewer systems user get the benefit of economy of scale .

• Reduce capital costs: Not required to spend huge money on software.

hardware or

• Reduce spending on technology infrastructure: minimal upfront spending in a pay-as-per use approach.

• Minimize maintenance and licensing software: Maintenance and software license updates are handled by service provider
• Monitor projects more effectively: Expenditurewithin budgets.
• Less personnel training is needed: Fewer people can handle more work so training requirement is less.
• Streamline business processes: Getting more work done in less time with less resources are possible.
• Improved flexibility: Possible to make fast changes in work  environment  without taking big risks.

Drawbacks of Cloud Computing

• If Internet connection is lost, the linkto the cloud is also lost.
• Security is a major concernas entire working with data and applications depend on other cloud vendors or providers.
• Although Cloud computing supports scalability, it does not  permit  the  control on these resourcesas these are not owned by the user or customer.
• customers may have to face restrictions on the availability of applications, operating systems and infrastructure options.
• Interoperability(ability of two or more applications that are required to support  a business need to work together by sharing data and other business-related resources) is an issue.

Cloud Computing Environment

The cloud computing environment consist of multiple types of clouds :

• Public Clouds: This environment can be used by the general  public  like  individuals, corporations and other types of organizations.
• Maintained by third parties or vendors over the Internet, and the services are offered on pay-per-use basis.
• These are also called provider clouds.
• Advantages &Limitation :
  • It is widely usedin the development, deployment and management of enterprise applications, at affordable costs.
  • It allows the organizations to deliver highly scalable and reliable  applications at more affordable costs.
  • limitations is security assuranceas data is at public servers.

•Private Clouds:

• This resides within the boundaries of an organizationand is used  exclusively  for the organization’s benefits.
• These are also called internal clouds. Advantages &Limitation :

• They improve average server utilization; thus reducing the costs
• Reduces operations costs and administrative overheads
• limitationis to invest in buying building and managing the clouds independently.

• Hybrid Clouds: This is a combination of both. With hybrid cloud, organizations might run non-core applications in a public cloud, while maintaining core

applications and sensitive data in-house in a private cloud. Advantages & Limitation:

• It is highly scalable and gives the power of both private and public clouds.
• It provides better security than the public cloud.
• The limitation is that the security features are not as good as the private cloud and complex to manage.

• Community Clouds: This is the sharing of computing infrastructure inbetween organizations of the same community. The risk isthat data may be stored with the data of competitors.
• Advantages & Limitation:
  • It allows establishing a low-cost private cloud.
  • It allows collaborative work on the cloud.
  • It allows sharing of responsibilities among the organizations.
  • It has better security than the public cloud.
  • The limitationis that the autonomy of the organization is lost and some of the security features are not as good as the private cloud. It is  not suitable in the cases where there is no collaboration.

Characteristics of Cloud

CLOUD COMPUTING SERVICEMODELS

Infrastructure  as  a  Service  (IaaS): In IaaS, cloud              provides the equipment to support operations, including storage, hardware, servers and networking components.

• The client typically pays on a per-use basis.
• Examples are: Amazon Web Service, Google Compute Engine, Open Stack and Eucalyptus etc.

Characteristics of IaaS

• Web access to the resources: The IaaS model enables the IT users to access infrastructure resources over the Internet.
• Centralized Management: These are managed centrally to ensures effective resource management and utilization.
• Elasticity and Dynamic Scaling: Depending on the load, IaaS services can be increased or decreased.
• Shared infrastructure: multiple IT users to share the same physical infrastructure and thus ensure high resource utilization.
• Metered Services: The services consumed will  be charged based on the  amount  of usage.

• Platform  as  a  Service (PaaS):PaaSprovides a              platform and environment to allow developers to build applications and services over the internet.
• It allows users to create software applicationsusing tools  supplied  by  the provider.
• In PaaS subscriber can choose the features (tools) that meet their requirements while discarding those that do not.
• Paid on pay per use basis
• Some of examples are: AWS Elastic Beanstalk, Cloud Foundry, Heroku, Force.com, EngineYardetc.

Software as a Service (SaaS):

• SaaS changes the way the software is delivered to the customers. SaaS provides users to access large variety of applications over internetthat are hosted  on  service provider’s infrastructure. For example, Google docs.
• end users need not manage and control the application.