UNIT I INTRODUCTION TO CLOUD COMPUTING Explain the term Cloud Computing History of Cloud Computing. Need for Cloud Computing. Explain the supporting areas of Cloud Computing. Introduction to various Internet Technologies. Introduction to Cloud Services Describe various communication technologies involved in Cloud Computing. Client server model Client server computing is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. Often clients and servers communicate over a computer network on separate hardware, but both client and server may reside in the same system. A server machine is a host that is running one or more server programs which share their resources with clients. A client does not share any of its resources, but requests a server's content or service function. Clients therefore initiate communication sessions with servers which await incoming requests. Peer-to-peer computing When computers moved into mainstream use, PCs (personal computers) were connected together through LANs (local area networks) to central servers. These central servers were much more powerful than the PCs so any large data processing took place on these servers.
Since then, PCs have become much more powerful, and they are able to handle the data processing locally rather than on central servers. Because of this, PC to PC, or peer-topeer computing can now occur when individual computers bypass central servers to connect and collaborate directly with each other. Distributed computing is a field of computer science that studies distributed systems. A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal. A computer program that runs in a distributed system is called a distributed program, and distributed programming is the process of writing such programs. Distributed computing also refers to the use of distributed systems to solve computational problems. In distributed computing, a problem is divided into many tasks, each of which is solved by one computer.
Grid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common goal. The Grid can be thought of as a distributed system with non-interactive workloads that involve a large number of files. What distinguishes grid computing from conventional high performance computing systems such as cluster computing is that grids tend to be more loosely coupled, heterogeneous, and geographically dispersed. Although a grid can be dedicated to a specialized application, it is more common that a single grid will be used for a variety of different purposes. Grids are often constructed with the aid of general-purpose grid software libraries known as middleware.
Collaborative Computing Collaborative computing is a fertile melange of technologies and techniques which facilitate people working together via computer-assisted means. Cloud Computing is Internet-based computing, whereby shared resources, software, and information are provided to computers and other devices on demand. Cloud computing refers to accessing computing resources that are typically owned and operated by a third-party provider on a consolidated basis in one, or usually more, data center locations. They feature on-demand provisioning and pay-as-you go resource billing, with minimal up-front investment.
How Cloud Computing Works All heavy lifting done by Web-based service Run through Interface Software Third party servers hold all information Software Saved data Security Used in online email services How does it Work? Front End Interface software and software licenses Word processing Custom programs Games Back end Network application servers and database storage
Lower computer costs. You don't need a high-powered and high-priced computer to run cloud computing's web-based applications. Since applications run in the cloud, not on the desktop PC, your desktop PC doesn't need the processing power or hard disk space demanded by traditional desktop software. When you're using webbased applications, your PC can be less expensive, with a smaller hard disk, less memory, more efficient processor, and the like. In fact, your PC in this scenario doesn't even need a CD or DVD drive, as no software programs have to be loaded and no document files need to be saved. Improved performance. With fewer bloated programs hogging your computer's memory, you'll see better performance from your PC. Put simply, computers in a cloud computing system boot and run faster because they have fewer programs and processes loaded into memory. Reduced software costs. Instead of purchasing expensive software applications, you can get most of what you need for free. That's right-most cloud computing applications today, such as the Google Docs suite, are totally free. That's a lot better
than paying $200+ for similar Microsoft Office software which alone may be justification for switching to cloud applications. Instant software updates. Another software-related advantage to cloud computing is that you're no longer faced with choosing between obsolete software and high upgrade costs. When the app is web-based, updates happen automatically and are available the next time you log into the cloud. When you access a web-based application, you get the latest version-without needing to pay for or download an upgrade. Improved document format compatibility. You don't have to worry about the documents you create on your machine being compatible with other users' applications or operating systems. In a world where Word 2007 documents can't be opened on a computer running Word 2003, all documents created by web-based applications can be read by any other user accessing that application. There are no format incompatibilities when everyone is sharing docs and apps in the cloud. Unlimited storage capacity. Cloud computing offers virtually limitless storage. Your computer's current 200 gigabyte hard drive is peanuts compared to the hundreds of petabytes (a million gigabytes) available in the cloud. Whatever you need to store, you can. Easier group collaboration. Sharing documents leads directly to collaborating on documents. To many users, this is one of the most important advantages of cloud computing-multiple users can collaborate easily on documents and projects. Because the documents are hosted in the cloud, not on individual computers, all you need is a computer with an Internet connection, and you're collaborating. Device independence. Finally, here's the ultimate cloud computing advantage: You're no longer tethered to a single computer or network. Change computers, and your existing applications and documents follow you through the cloud. Move to a portable device, and your apps and docs are still available. There's no need to buy a special version of a program for a particular device, or to save your document in a device-specific format. Your docs and their apps are the same no matter what computer or other device you're using.
A few of the risks related to cloud computing: Requires a constant Internet connection. Cloud computing is impossible if you can't connect to the Internet. Since you use the Internet to connect to both your applications and documents, if you don't have an Internet connection you can't access anything, even your own documents. A dead Internet connection means no work, period and, in areas where Internet connections are few or inherently unreliable, this could be a deal-breaker. When you're offline, cloud computing simply doesn't work. Doesn't work well with low-speed connections. Similarly, a low-speed Internet connection, such as that found with dial-up services, makes cloud computing painful at best and often impossible. Web-based apps require a lot of bandwidth to download, as do large documents. If you're laboring with a low-speed dial-up connection, it might take seemingly forever just to change from page to page in a document, let alone to launch a feature-rich cloud service. In other words, cloud computing isn't for the broadband-impaired. Can be slow. Even on a fast connection, web-based applications can sometimes be slower than accessing a similar software program on your desktop PC. Everything about the program, from the interface to the current document, has to be sent back and forth from your computer to the computers in the cloud. If the cloud servers happen to be backed up at that moment, or if the Internet is having a slow day, you won't get the instantaneous access you might expect from desktop apps. Features might be limited. This situation is bound to change, but today many webbased applications simply aren't as full-featured as their desktop-based brethren. For example, you can do a lot more with Microsoft PowerPoint than with Google Presentation's web-based offering. The basics are similar, but the cloud application lacks many of PowerPoint's advanced features. If you're a power user, you might not want to leap into cloud computing just yet. Stored data might not be secure. With cloud computing, all your data is stored on the cloud. How secure is the cloud? Can unauthorized users gain access to your confidential data? Cloud computing companies say that data is secure, but it's too
early in the game to be completely sure of that. Only time will tell if your data is secure in the cloud. Stored data can be lost. Theoretically, data stored in the cloud is unusually safe, replicated across multiple machines. But on the off chance that your data goes missing, you have no physical or local backup. (Unless you methodically download all your cloud documents to your own desktop which few users do.) Put simply, relying on the cloud puts you at risk if the cloud lets you down. Advantages of the Cloud: Unlimited, everywhere access Reduction in hardware costs Reduction in software costs No physical space in office Increased computing power Automatic redundancy. Eco-Friendly Incentives for Cloud Computing Of course another incentive to opt for cloud computing is that it is more environmentally friendly. Reducing the number of hardware components and replacing them with cloud computing systems reduces energy costs for running hardware and cooling as well as reducing carbon dioxide emissions and conserving energy. Moving applications to the cloud can potentially reduce energy costs for running and cooling hardware. This can also work in combination with government tax incentives to go green and power companies added incentives.
Advantages of Cloud Development One of the underlying advantages of cloud development is that of economy of scale. By taking advantage of the infrastructure provided by a cloud computing vendor, a developer can offer better, cheaper, and more reliable applications than is possible within a single enterprise. The application can utilize the full resources of the cloud, if needed without requiring a company to invest in similar physical resources. Speaking of cost, because cloud services follow the one-to-many model, cost is significantly reduced over individual desktop program deployment. Instead of purchasing or licensing physical copies of software programs (one for each desktop), cloud applications are typically rented, priced on a per-user basis. It s more of a subscription model than an asset purchase (and subsequent depreciation) model, which means there s less up-front investment and a more predictable monthly expense stream. IT departments like cloud applications because all management activities are managed from a central location rather than from individual sites or workstations. This enables IT staff to access applications remotely via the web. There s also the advantage of quickly outfitting users with the software they need (known as rapid provisioning), and adding more computing resources as more users tax the system (automatic scaling). When you need more storage space or bandwidth, companies can just add another virtual server from the cloud. It s a lot easier than purchasing, installing, and configuring a new server in their data center. For developers, it s also easier to upgrade a cloud application than with traditional desktop software. Application features can be quickly and easily updated by upgrading the centralized application, instead of manually upgrading individual applications located on each and every desktop PC in the organization. With a cloud service, a single change affects every user running the application, which greatly reduces the developer s workload.
Disadvantages of Cloud Development Perhaps the biggest perceived disadvantage of cloud development is the same one that plagues all web-based applications: Is it secure? Web-based applications have long been considered potential security risks. For this reason, many businesses prefer to keep their applications, data, and IT operations under their own control. That said, there have been few instances of data loss with cloud-hosted applications and storage. It could even be argued that a large cloud hosting operation is likely to have better data security and redundancy tools than the average enterprise. In any case, however, even the perceived security danger from hosting critical data and services offsite might discourage some companies from going this route. Another potential disadvantage is what happens if the cloud computing host goes offline. Although most companies say this isn t possible, it has happened. Amazon s EC2 service suffered a massive outage on February 15, 2008, that wiped out some customer application data. (The outage was caused by a software deployment that erroneously terminated an unknown number of user instances.) For clients expecting a safe and secure platform, having that platform go down and your data disappear is a somewhat rude awakening. And, if a company relies on a third-party cloud platform to host all of its data with no other physical backup, that data can be at risk. Infrastructure as a Service Infrastructure as a Service (IaaS) is delivery of the computing infrastructure as a fully outsourced service. Some of the companies that provide infrastructure services are Google, IBM, and Amazon Web Services (AWS) etc. Managed hosting and development environments are the services included in IaaS. The user can buy the infrastructure according to the requirements at any particular point of time instead of buying the infrastructure that might not be used for months. IaaS operates on a Pay as you go model ensuring that the users pay for only what they are using. Virtualization enables IaaS providers to offer almost unlimited instances of servers to customers and make cost-
effective use of the hosting hardware. IaaS users enjoy access to enterprise grade IT Infrastructure and resources that might be very costly if purchased completely. Thus dynamic scaling, usage based pricing, reduced costs and access to superior IT resources are some of the benefits of IaaS. IaaS is also sometimes referred to as Hardware as a Service (HaaS). An Infrastructure as a Service offering also provides maximum flexibility because just about anything that can be virtualized can be run on these platforms. This is perhaps the biggest benefit of an IaaS environment. For a startup or small business, one of the most difficult things to do is keep capital expenditures under control. By moving your infrastructure to the cloud, you have the ability to scale as if you owned your own hardware and data center. Platform as a Service Providers such as Windows Azure and Google App Engine (GAE) provide a platform that users write to. In this case, the term platform refers to something that abstracts away the lower levels of the stack. This application runs in a specialized environment. PaaS offers a development platform for developers. The end users write their own code and the PaaS provider uploads that code and presents it on the web. SalesForce.com s Force.com is an example of PaaS. PaaS provides services to develop, test, deploy, host and maintain applications in the same integrated development environment. It also provides some level of support for the creation of applications. Thus PaaS offers a faster more cost effective model for application development and delivery. The PaaS provider manages upgrades, patches and other routine system maintenance. PaaS is based on a metering or subscription model so users only pay for what they use. Users take what they need without worrying about the complexity behind the scenes. Software as a Service Software as a Service (SaaS) is the service based on the concept of renting software from a service provider rather than buying it yourself. The software is hosted on centralized network servers to make functionality available over the web or intranet. Also known as software on demand it is currently the most popular type of cloud computing because
of its high flexibility, great services, enhanced scalability and less maintenance. Yahoo mail, Google docs, CRM applications are all instances of SaaS. With a web-based CRM all that employees need to do is register and login to the central system and import any existing customer data. The service provider hosts both the application and the data so the end user is free to use the service from anywhere. SaaS is very effective in lowering the costs of business as it provides the business an access to applications at a cost normally far cheaper than a licensed application fee which is possible due to its monthly fees based revenue model. With SaaS user need not worry about installation or upgrades Discovering Cloud Services Amazon Amazon, one of the largest retailers on the Internet, is also one of the primary providers of cloud development services. Think of it this way: Amazon has spent a lot of time and money setting up a multitude of servers to service its popular website, and is making those vast hardware resources available for all developers to use. Amazon s service lets customers choose from three sizes of virtual servers: Small, which offers the equivalent of a system with 1.7GB of memory, 160GB of storage, and one virtual 32-bit core processor Large, which offers the equivalent of a system with 7.5GB of memory, 850GB of storage, and two 64-bit virtual core processors Extra large, which offers the equivalent of a system with 15GB of memory, 1.7TB of storage, and four virtual 64-bit core processors In other words, you pick the size and power you want for your virtual server, and Amazon does the rest. Google App Engine Google is a leader in web-based applications, so it s not surprising that the company also offers cloud development services. These services come in the form of the Google App Engine, which enables developers to build their own Web applications utilizing the same infrastructure that powers Google s powerful applications. The Google App Engine provides a fully integrated application environment.
Google offers a robust cloud development environment. It includes the following features: Dynamic web serving Full support for all common web technologies Persistent storage with queries, sorting, and transactions Automatic scaling and load balancing APIs for authenticating users and sending email using Google Accounts In addition, Google provides a fully featured local development environment that simulates the Google App Engine on any desktop computer. Salesforce.com Salesforce.com is probably best known for its sales management SaaS, but it s also a leader in cloud computing development. The company s cloud computing architecture is dubbed Force.com. The platform as a service is entirely on-demand, running across the Internet. Salesforce provides its own Force.com API and developer s toolkit. Pricing is on a per log-in basis. Summary Probably more than anything we ve seen in IT since the invention of timesharing or the introduction of the PC, cloud computing represents a paradigm shift in the delivery architecture of information services. Google, Yahoo, Amazon, and others have built large, purpose-built architectures to support their applications and taught the rest of the world how to do massively scalable architectures to support compute, storage, and application services. Cloud computing is about moving services, computation and/or data for cost and business advantage off-site to an internal or external, location-transparent, centralized facility or contractor. By making data available in the cloud, it can be more easily and ubiquitously accessed, often at much lower cost, increasing its value by enabling opportunities for enhanced collaboration, integration, and analysis on a shared common platform.
Short Questions: 1. Define distributed computing. 2. What is utility computing? 3. What is cloud computing? 4. Compare Distributed, Grid, Cloud computing. 5. List out the cloud services. 6. What are the advantages of IaaS? 7. List the risks involved in cloud computing. 8. Write short notes on cloud service providers. 9. Mention some properties of cloud computing. 10. What are the advantages of Cloud computing?