In this chapter, the authors describe cloud computing from different angles. They clear up some misconceptions and ambiguities about it to reach a common understanding of the topic. Then, they enumerate cloud attributes and its essential characteristics. The authors consider cloud computing as a core topic and various things emerging around it such as its services and delivery models, its economic aspects, applications, usages, challenges, and so on. Cloud computing is a focal technological point for various technologies and shares its characteristics and features with them. Cloud is a dual technology for many emerging technologies such as Internet of Things, Smart Grid, Smart City, Green Computing, and Home Networking. On the other hand, cloud complements the growth and the development of these technologies. At the end, the authors explore these complementary technologies.
Top1. Introduction
On February 24, 2007, the term “cloud computing” was coined and that day Cloud Expo (Cloud Computing Expo, 2012) was announced. In 2007, the first Cloud Expo took place in New York City with 450 delegates. And in 2008, the number of delegates in Cloud Expo was with more than 10,000 and over 600 sponsors and exhibitors. This direct observation shows the importance and the rapid evolution of cloud computing.
Since the birth of TCP/IP, people have been drawing TCP/IP networks on diagrams like cloud metaphor. This metaphor resonates for the same reason the “electron cloud” is a useful metaphor for the behavior of electrons. A cloud represents a black-box: we do not have to know its internal details, just its behaviors or interfaces are needed by users. On the other hand, cloud computing is a new term to define and to represent infinity and utility computing in order to deliver elastic information technology (IT) over the Internet. However, the precise definition of cloud computing (Armbrust et al., 2009) varies widely and depends on the context, since clouds are not mature enough and they are in a rapid, continuous, and technological evolution stage.
In the cloud computing world, IT capabilities are delivered on the fly and on-demand through the Internet when the need arises instead of drawing from local and desktop computers. Many design and architectural patterns (Armbrust et al., 2010) are emerging around cloud computing that makes it difficult to fit everything into a perfect definition. For instance, from the marketing point of view (Buyya, Yeo, & Venugopal, 2008), the term “cloud computing” is vague and meaningless due to its widely misuse and extensive overuse. In the recent years of appearance of cloud computing, any software, service, tool, and product IT companies provide, offer, or sell, using Web technologies, are labeled ’cloud’. They are somehow in the cloud or are called “cloud computing.”
The other face of cloud computing is outsourcing. Software companies are rapidly moving more and more of their services, software, and applications to cloud computing due to users’ radical, urgent, growing, fluctuating, seasonal, competing, enormous, and economic demands. These number of demands cannot be met by running users’ local and private infrastructures. On the other hand, if users invest in private infrastructures and buy lots of servers during falling and low demands times servers would be under-utilized; this would largely lead to wasting IT resources and energy. In addition, local infrastructures require IT system administration tasks such as installation, deployment, configuration, patching, upgrading, etc. With outsourcing, these all shift to cloud computing.
During the emergence and the evolution of computing models, we have seen computing technologies like time-sharing, mainframe, high performance computing (HPC), cluster computing, grid computing, and service oriented computing. We observe that some of these computing models are the building blocks of cloud computing such as time-sharing and service oriented computing while the others could be provided and be offered as a service from a right cloud provider. For example, there are many cloud offerings for HPC as a Service, Grid as a Service.
Again we ask this question: what is cloud computing and why should we care? We define it in simple terms from another angle: cloud computing simply means using remote, large and Internet-based data centers as if they belong to your own private infrastructure. This is similar to large pipes for computing, network, software, data, and information.
Large software and Internet companies including Salesforce.com, Google, Yahoo! and Amazon are pushing forward to deliver information and software over the Internet (Armbrust et al., 2010). In accessing services, users do not know what is really happening and what is behind cloud infrastructures of these companies. It is like a Google search that we do not know anything about our search process like from where our search result is coming, what city the servers are located in, etc.