Abstract’ Computers have become an unavoidable
part of life. Any field you name be it research, banking enterprises, computers are needed everywhere. As the use of computers in our day-to-day life increases, so does the need of the computing resources. For companies like Google and Microsoft, tackling the resources as and when they need it is not a problem. But when it comes to smaller enterprises, affordability becomes a huge factor. Problems like machines failure, hard drive crashes, software bugs, etc increases as the infrastructure increases. This might be a big headache for such a community. Cloud Computing offers a solution to this situation. Cloud computing is a paradigm shift in which computing is moved away from personal computers and even the individual enterprise application server to a ‘cloud’ of computers. Cloud computing is basically an Internet-based network made up of large numbers of servers – mostly based on open standards, modular and inexpensive. Clouds contain vast amounts of information and provide a variety of services to large numbers of people. This paper describes cloud computing, a computing platform based upon internet. The paper defines cloud, outlines the cloud architecture and its major components.
I INTRODUCTION TO CLOUD COMPUTING
Cloud Computing can be broadly defined as several different methods to deliver information or services to customers who pay for what they use.
Cloud computing is the style of computing where massively scaled IT related capabilities are provided as a service across the internet to multiple external customers and are billed by consumption. Many cloud computing providers have popped up and there is a considerable growth in the usage of this service. Google, Microsoft, Yahoo, IBM and Amazon have started providing cloud computing services. Amazon is the pioneer in this field. Smaller companies like SmugMug, which is an online photo hosting site, has used cloud services for the storing all the data and doing some of its services.
Thus, it is a new mechanism to deliver products
from a producer to a consumer. Of course, we
have a consumer who wants or needs to utilize information.
Who is the customer?
The customer can be an external person or company who is paying for a service or information. The customer could also be an internal customer, such as the application owner who is using services that another department within the same company is offering, who is being charged for consumption. This is where we come to know about the types of cloud computing:
1) Public Cloud
2) Private Cloud
3) Hybrid cloud
Cloud computing implies the services provided over the internet as both the hardware and system software on the Data-centre’s provided by service provider. Cloud computing comprises following two levels:
‘ front end users: customers or users using those service on their device
‘ back end users: service provider or vendor managing the services
Part of the confusion in cloud computing is that there are two completely different customers for two different types of clouds. One type of cloud the customer gets information and services externally (public cloud) and the other type gets theirs internally (private cloud). With the public cloud, the customer owns no storage or server and has no capital expenditures; they simply want to buy what they need on demand. The other customer is an internal customer so the company spends capital to either provide services and data internally, or spends capital to provide the servers, storage, networking, and applications (capital spending) for an external customer. In addition, there are many different ways to use the cloud. Take the point-of-view of the producer. The producer can be an internal department offering services, which is called a private cloud. The producer can also be an external company that is supplying a server, storage, rack space, and electricity, and essentially supplies the capital for the information or service. As an example, let’s say that I am a product manager, and I have an application that I want to put into production. What do I need to put together to roll out this product? Well, Indeed to find a server and storage for the data. I also need to find rack space for the server, and I need electricity, to name the big items. Basically, a capital investment is made to put my application into production in my company’s data center. With an external (public) cloud, I do not do any of these things; someone else builds the space and provides the capital investment. Thus, we have a new way of doing business where the customer buys on demand, and the supplier charges for what the customer uses. This concept is similar to cable television on demand, I only pay for the movies that I want to watch. At issue are the details of providing the data to the users, and securing that data. A hybrid cloud environment consisting of multiple internal and/or external providers, will be typical for most enterprises". A hybrid cloud can describe configuration combining a local device, such as a Plug computer with cloud services. It can also describe configurations combining virtual and physical, collocated assets’for example, a mostly virtualized environment that requires physical servers, routers, or other hardware such as a network appliance acting as a firewall or spam filter.
II HISTORY
The Cloud is a metaphor for the Internet, derived from its common depiction in network diagrams
(or more generally components which are managed by others) as a cloud outline. The underlying concept dates back to 1960 when John McCarthy opined that "computation may someday be organized as a public utility" (indeed it shares characteristics with service bureaus which date back to the 1960s) and the term The Cloud was already in commercial use around the turn of the 21st century. Cloud computing solutions had started to appear on the market, though most of the focus at this time was on Software as a service. 2007 saw increased activity, including Goggle, IBM and a number of universities embarking on a large scale cloud computing research project, around the time the term started gaining popularity in the mainstream press. It was a hot topic by mid-2008 and numerous cloud computing events had been scheduled.
III HOW IT’S WORK?
Let’s say you’re an executive at a large corporation. Your particular responsibilities include making sure that all of your employees have the right hardware and software they need to do their jobs. Buying computers for everyone isn’t enough — you also have to purchase software or software licenses to give employees the tools they require. Whenever you have a new hire, you have to buy more software or make sure your current software license allows another user. It’s so stressful that you find it difficult to go to sleep on your huge pile of money every night.
Soon, there may be an alternative for executives like you. Instead of installing a suite of software for each computer, you’d only have to load one application. That application would allow workers to log into a Web-based service which hosts all the programs the user would need for his or her job. Remote machines owned by another company would run everything from e-mail to word processing to complex data analysis programs. It’s called cloud computing, and it could change the entire computer industry.
IV CHARACTERISTICS
1. Agility improves with users’ ability to re-provision technological infrastructure resources.
2. Virtualization technology allows servers and storage devices to be shared and utilization be increased. Applications can be easily migrated from one physical server to another.
3. Reliability is improved if multiple redundant sites are used, which makes well-designed cloud computing suitable for business continuity and disaster recovery.
4. Performance is monitored, and consistent and loosely coupled architectures are constructed using web services as the system interface.
5. Maintenance of cloud computing applications is easier, because they do not need to be installed on each user’s computer and can be accessed from different places.
V ISSUES
1. Privacy
The cloud model has been criticized by privacy advocates for the greater ease in which the companies hosting the cloud services control, and thus, can monitor at will (whether permitted or not by their customers), the communication between the host company and the end user, as well as the user’s stored data. Instances such as the secret NSA program, working with AT&T, and Verizon, which recorded over 10 million telephone calls between American citizens, causes uncertainty among privacy advocates, and the greater powers it gives to telecommunication companies to monitor user activity.
2. Compliance
In order to obtain compliance with regulations including FISMA, HIPAA, and SOX in the United States, the Data Protection Directive in the EU and the credit card industry’s PCI DSS, users may have to adopt community or hybrid deployment modes that are typically more expensive and may offer restricted benefits. This is how Google is able to "manage and meet additional government policy requirements beyond FISMA" and Rackspace Cloud or QubeSpace are able to claim PCI compliance.
3. Legal
As with other changes in the landscape of computing, certain legal issues arise with cloud computing, including trademark infringement, security concerns and sharing of proprietary data resources.
The Electronic Frontier Foundation has criticized the United States government for considering during the Megaupload seizure process that people lose property rights by storing data on a cloud computing service.
VI ARCHITECTURE
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.
When talking about a cloud computing system, it’s helpful to divide it into two sections: the front end and the back end. They connect to each other through a network, usually the Internet. The front end is the side the computer user, or client, sees. The back end is the "cloud" section of the system.
The front end includes the client’s computer (or computer network) and the application required to access the cloud computing system. Not all cloud computing systems have the same user interface. Services like Web-based e-mail programs leverage existing Web browsers like Internet Explorer or Firefox. Other systems have unique applications that provide network access to clients.
On the back end of the system are the various computers, servers and data storage systems that create the "cloud" of computing services. In theory, a cloud computing system could include practically any computer program you can imagine, from data processing to video games. Usually, each application will have its own dedicated server.
A central server administers the system, monitoring traffic and client demands to ensure everything runs smoothly. It follows a set of rules called protocols and uses a special kind of software called middleware. Middleware allows networked computers to communicate with each other.
f a cloud computing company has a lot of clients, there’s likely to be a high demand for a lot of storage space. Some companies require hundreds of digital storage devices. Cloud computing systems need at least twice the number of storage devices it requires to keep all its clients’ information stored. That’s because these devices, like all computers, occasionally break down. A cloud computing system must make a copy of all its clients’ information and store it on other devices. The copies enable the central server to access backup machines to retrieve data that otherwise would be unreachable. Making copies of data as a backup is called redundancy.
LAYERS:
CLIENT
A cloud client consists of computer hardware and/or computer software that relies on cloud computing for application delivery, or that is specifically designed for delivery of cloud services and that, in either case, is essentially useless without it. Examples include some computers, phones and other devices, operating systems and browsers.