Indroduction :
Now a days Cloud Computing has become very critical aspect of every IT infrastructure. It is very difficult to imagine any general, block or decision without the mention of cloud computing. Through it is all prevalent, no one really knows exact definition of cloud computing system so, what is cloud computing after our? Simply put, Cloud Computing is the delivery of computing services over the Internet. The services that consists of server, storage, database, networking, software analytics and more. you can compare this to uses of utilities such as water, telephone, gas or electricity. similarly to these utilities, computing services are delivered on demand. This enable organisation to quickly and effectively either add or Delete resources.
Cloud computing at glance:
1. Cloud Computing is a new paradigm for the dynamic provisioning of Computer Services.
2. Computing services such as storage, databases, service extra are available on demand. This is similar to using utilities like electricity, telephone etc.
3. User of these services will pay to providers only when they use the service.
4. User access services based on their needs without knowing where the services are hosted.
5. Consumers/users no longer need to invest heavily in building and maintaining their own complex IT infrastructure.
6. Web 2.0 Technologies and advancement in hardware components have made Cloud Computing possible and an attractive opportunity.
Fig:Cloud computing needs
Defining a cloud:
1. Defining of cloud is associated with various Technologies depending on the context.
2.Often , it is associated with virtualized infrastructure, hardware on demand, software and services or IT outsourcing.
3 Historically , cloud is referred to as a depiction of network abstraction in network diagrams in telecommunication domain. Currently the same depiction is used to represent Internet.
4. Internet plays a fundamental role in cloud computing as a medium or platform through which other cloud services are delivered.
5. Going by this interpretation , cloud in cloud computing refers to internet oriented computing.
6. One of the definition of cloud computing provides by armbrust reflect this aspect of cloud computing: Cloud Computing refers to both the application delivered as service over the internet and the hardware and system software in the data centres that provide the services.
7. Cloud Computing in a way touches the entire stack :from the hardware to high-level software services and applications.
8. Essentially, every layer of this that can be delivered, measured and prices as service.
9. This new approach has not only changed the way we develop software but also the way we think of its deployments.
10. Cloud benefits spectrum of users from single user who could access single document over internet to big IT companies who want to deploy part of its IT infrastructure in cloud.
11. Basis on this notation , National Institute of standard and technologies defines cloud computing as a model for enabling ubiquitous, convenient, on demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with the minimal management effort or service provider interaction.
12. Three important characteristics of cloud based services are
a. the service is accessible from anywhere via the web browser or web service application program interface(API).
b. Zero capital expenditure is necessary to get started.
c. You pay only for what you use as you use it.
Cloud computing reference model:
1. Cloud Computing reference model can be envisioned as a stack. It comprises of three layers are representing three categories of the offerings. These categories are related to each other.
2. Three categories of offering in cloud computing are infrastructure as a service(Iaas) , platform as a service(Paas) , software as a service(Saas).
Infrastructure as a service(Iaas):
● Deliver infrastructure on demand in the form of virtual hardware, storage, and networking.
● User can request for Hardware which is provided in the form of virtual systems.
● Users are provided with configuration tools and services in order to configure their virtual environment as per their need.
● For example, system engineer can request RedHatLinux machine with desired configuration. using tools provided by the service provider systems engineer can prepare the this Linux machine as if it is available in the form of hardware sitting right next to him.
● Examples- Amazon EC2 Amazon S3, vCloud.
Platform as a service(Paas) :
● they deliver scalable and Elastic run time environment on demand and force the execution of application.
● Examples-Windows Azure, Hadoop.
Software as a service(Saas) :
● Provide applications and services on demand.
● Examples- Google documents, Facebook.
Fig:Cloud computing reference model
Characteristics and benefits:
characteristics include:
1. No upfront commitments- provision or deprovision services as and when needed without any compulsion on time of use.
2. On demand access- get wherever you want at the click of a button.
3. Pay as you use-similar to utilities like electricity and telephone.
4. Pricing - with improved hardware and infrastructure across the globe, overall cloud services prices are very attractive.
5. Seamless use of third party services.
6. Energy Efficiency.
7. Resource allocation efficiency.
These characteristics bring benefits such as-
1. Increased economical return-
a. No capital cost - as there is no need to create any hardware infrastructure at end user side there is significant less cost involved at the beginning.
b. Reduced maintenance and operational- As there is no infrastructure setup that user and, there is no hassle of infrastructure maintenance.
2. Increased flexibility in defining and structuring software systems- as IT infrastructure is rented on need basis, organisation can now freely think of bigger volumes and scales without worrying about initial capital cost. For example, organisations can add more server servers to process workload Spikes and dismiss them when they are no longer needed.
3. Ease of scalability- small organisation can leverage potentially unlimited resources available in cloud.
4. 24/7 availability- service level agreements from CSP’s to provide 99% availability of the services provided.
5. New opportunities- By combining multiple services from different vendors, new concept or solution can be in envisioned and Developed. This was not possible in pre-cloud era.
