1. Introduction to cloud computing
Cloud Computing is the use of common software, functionality or business applications from a remote server that is accessed via the Internet. Basically, the Internet is the "cloud" of applications and services that are available for access by subscribers utilizing a modem from their computer. With Cloud Computing, one simply logs into desired computer applications - such as sales force or office automation programs, web services, data storage services, spam filtering, or even blog sites. Generally, access to such programs is by monthly or annual paid subscription. Through Cloud Computing, businesses may prevent financial waste, better track employee activities, and avert technological headaches such as computer viruses, system crashes, and loss of data. [pic]
a) Cloud Computing Is User Centric: Once as a user are connected to the cloud, whatever is stored there—documents, messages, images, applications, whatever—becomes authorized to the user access them. b) Cloud Computing Is Task-Centric: Instead of focusing on the application and what it can do, the focus is on what one need done and how the application can do it for us. Traditional applications—word processing, spreadsheets, email, and so on—are becoming less important than the documents they create. c) Cloud Computing Is Powerful: Connecting hundreds or thousands of computers together in a cloud creates a wealth of computing power impossible with a single desktop PC. d) Cloud Computing Is Accessible: Because data is stored in the cloud, users can instantly retrieve more information from multiple repositories. We are not limited to a single source of data, as we do with a desktop PC. e) Cloud Computing Is Intelligent: With all the various data stored on the computers in a cloud, data mining and analysis are necessary to access that information in an intelligent manner. f) Cloud Computing Is Programmable: Many of the tasks necessary with cloud computing must be automated. For example, to protect the integrity of the data, information stored on a single computer in the cloud must be replicated on other computers in the cloud. If that one computer goes offline, the cloud’s programming automatically redistributes that computer’s data to a new computer in the cloud. 2. Services of Cloud Computing
The rapid improvement of the capacity of online connectivity gave birth to cloud computing. Although the term was already used since the 90s, the actual adoption of cloud computing in relation to online computing started in the 21st century. Cloud computing is a general term for anything that involves delivering hosted services over the Internet. These services are broadly divided into three categories: a) Infrastructure-as-a-Service (IaaS): Infrastructure as a Service is a provision model in which an organization outsources the equipment used to support operations, including storage, hardware, servers and networking components. The service provider owns the equipment and is responsible for housing, running and maintaining it. The client typically pays on a per-use basis. Characteristics and components of IaaS include:
• Utility computing service and billing model: (charges per usage) • Automation of administrative tasks.
• Dynamic scaling.
• Desktop virtualization: (multiple network,, centrally located server.) • Policy-based services.
• Internet connectivity.
b) Platform-as-a-Service (PaaS): Platform as a Service (PaaS) is a way to rent hardware, operating systems, storage and network capacity over the Internet. The service delivery model allows the customer to rent virtualized servers and associated services for running existing applications or developing and testing new ones. Characteristics of Paas include:
• Operating system features can be changed and upgraded...