1 CLOUD COMPUTING INTRODUCTION 1. Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over a network (typically the Internet). The name comes from the use of a cloud-shaped symbol as an abstraction for the complex infrastructure it contains in system diagrams. Cloud computing entrusts remote services with a user's data, software and computation. It relies on sharing of resources to achieve coherence and economies of scale similar to a utility (like the electricity grid) over a network. At the foundation of cloud computing is the broader concept of converged infrastructure and shared services. 2. Cloud computing is receiving a great deal of attention, both in publications and among users, from individuals at home to a large number of organisations. Yet it is not always clearly defined. It is a subscription-based service where we can obtain networked storage space and computer resources. The most important part of the equation is having internet access. One way to think of cloud computing is to consider our experience with email. Our email client, if it is Yahoo!, Gmail, Hotmail, and so on, takes care of housing all of the hardware and software necessary to support our personal email account. 3. Our email is not housed on our physical computer; our access it through an internet connection, and we can access it anywhere. Our email is different than software installed on our computer, such as a word processing program. When we create a document using word processing software, that document stays on the device we used to make it unless we physically move it. An email client is similar to how cloud computing works. Except instead of accessing just our email, we can choose what information we have access to within the cloud. HISTORY 4. Cloud computing appears to derive from the practice of using drawings of stylized clouds to denote networks in diagrams of computing and communications systems. The word cloud is used as a metaphor for the Internet, based on the standardized use of a cloud-like shape to denote a network on telephony schematics and later to depict the Internet in computer network diagrams as an abstraction of the underlying infrastructure it represents. The cloud symbol was used to represent the Internet as early as 1994. 5. In the 1950s; when large-scale mainframe became available in academia and corporations, accessible via thin clients / terminal computers. In the 1990s, telecommunications companies, who previously offered primarily dedicated point-to-point data circuits, began offering virtual private network (VPN) services with comparable quality of service but at a much lower cost. Cloud computing extends this boundary to cover servers as well as the network infrastructure. 6. Whereas in 1990s, telecommunications companies, who previously offered primarily, dedicated point-to-point data circuits, began offering Virtual Private Network (VPN) services with comparable quality of service but at a much lower cost. By
2 switching traffic to balance utilization as they saw fit, they were able to utilize their overall network bandwidth more effectively. The cloud symbol was used to denote the demarcation point between that which was the responsibility of the provider and that which was the responsibility of the users. Cloud computing extends this boundary to cover servers as well as the network infrastructure. As computers became more prevalent, scientists and technologists explored ways to make large-scale computing power available to more users through time sharing, experimenting with algorithms to provide the optimal use of the infrastructure, platform and applications with prioritized access to the CPU and efficiency for the end users. Definition 7. The name comes from the use of a cloud-shaped symbol as an abstraction for the complex infrastructure it contains in system diagrams. Cloud computing entrusts remote services with a user's data, software and computation. There are many types of public cloud computing:- (a) Infrastructure as a Service (IaaS). It is a most basic cloud service model in which providers offer computers as physical or more often as virtual machines and other resources. The virtual machines are run as guests by a hyper-visor such as Xen or KVM. Pools of hyper-visors within the cloud operational support system support large numbers of virtual machines and the ability to scale services up and down according to customers' varying requirements. To deploy their applications, cloud users install operating system images and their application software on the cloud infrastructure. In this model, it is the cloud user who is responsible for patching and maintaining the operating systems and application software. (b) Platform as a Service (PaaS). In the PaaS model, cloud providers deliver a computing platform typically including operating system, programming language execution environment, database and web server. Application developers can develop and run their software solutions on a cloud platform without the cost and complexity of buying and managing the underlying hardware and software layers. With some PaaS offers, the underlying computer and storage resources scale automatically to match application demand such that cloud user does not have to allocate resources manually. (c) Software as a Service (SaaS). In the SaaS model, cloud providers install and operate application software in the cloud and cloud users access the software from cloud clients. The cloud users do not manage the cloud infrastructure and platform on which the application is running. This eliminates the need to install and run the application on the cloud user's own computers simplifying maintenance and support. What makes a cloud application different from other applications is its scalability. This can be achieved by cloning tasks onto multiple virtual machines at run-time to meet the changing work demand. This process is transparent to the cloud user who sees only a single access point. To accommodate a large number of cloud users, cloud applications can be multi-tenant, that is, any machine serves more than one cloud user organization.
3 (d) Network as a Service (NaaS). A category of cloud services where the capability provided to the cloud service user is to use network/transport connectivity services and/or inter-cloud network connectivity services. NaaS involves the optimization of resource allocations by considering network and computing resources as a unified whole. (e) Storage as a Service (STaaS). It is a business model in which a large service provider rents space in their storage infrastructure on a subscription basis. The economy of scale in the service provider's infrastructure allows them to provide storage much more cost effectively than most individuals or corporations can provide their own storage, when total cost of ownership is considered. Storage as a Service is often used to solve offsite backup challenges. (f) Security as a Service (SECaaS). It is a business model in which a large service provider integrates their security services into a corporate infrastructure on a subscription basis more cost effectively than most individuals or corporations can provide on their own, when total cost of ownership is considered. These security services often include authentication, anti-virus, anti-malware/spyware, intrusion detection, and security event management, among others. (g) Data as a Service (DaaS). It is a cousin of SaaS. Like all members of the "as a Service" (aas) family, DaaS is based on the concept that the product, data in this case, can be provided on demand to the user regardless of geographic or organizational separation of provider and consumer. Additionally, the emergence of service-oriented architecture (SOA) has rendered the actual platform on which the data resides also irrelevant. This development has enabled the recent emergence of the relatively new concept of DaaS. (h) Database as a Service (DBaaS). Some cloud platforms offer options for using a database as a service, without physically launching a virtual machine instance for the database. In this configuration, application owners do not have to install and maintain the database on their own. Instead, the database service provider takes responsibility for installing and maintaining the database, and application owners pay according to their usage. (j) Test Environment as a Service (TEaaS). Also referred to as "on-demand test environment," is a test environment delivery model in which software and its associated data are hosted centrally (typically in the internet cloud) and are typically accessed by users using a thin client, normally using a web-browser over the Internet. (k) Desktop Virtualization. Sometimes called Client Virtualization, as a concept, separates a personal computer desktop environment from a physical machine using the client-server model of computing. Virtual desktop infrastructure, sometimes referred to as Virtual Desktop Interface (VDI) is the server computing model enabling desktop virtualization, encompassing the hardware and software systems required to support the virtualized environment.
4 (l) API as a Service (APIaaS). It is a service platform that enables the creation and hosting of APIs (application programming interfaces). These API's normally provide multiple entry points for API calls ranging from REST, XML web services or TCP/IP. (m) Backend as a Service (BaaS). Also known as "mobile backend as a service" (MBaaS), is a model for providing web and mobile application developers with a way to link their applications to backend cloud storage while also providing features such as user management, push notifications, and integration with social networking services. These services are provided via the use of custom Software Development Kits (SDKs) and Application Programming Interfaces (APIs). Types of Clouds 8. There are different types of clouds that we can subscribe to depending on our needs. As a home user or small business owner, we will most likely use public cloud services. (a) Public Cloud A public cloud can be accessed by any subscriber with an internet connection and access to the cloud space. (b) Private Cloud A private cloud is established for a specific group or organization and limits access to just that group. (c) Community Cloud A community cloud is shared among two or more organizations that have similar cloud requirements. (d) Hybrid Cloud A hybrid cloud is essentially a combination of at least two clouds, where the clouds included are a mixture of public, private, or community. Characteristics 9. Cloud computing exhibits the following key characteristics:- (a) Agility. It improves with users' ability to re-provision technological infrastructure resources. (b) Application Programming Interface (API). API accessibility to software that enables machines to interact with cloud software in the same way the user interface facilitates interaction between humans and computers. Cloud computing systems typically use REST-based APIs. (c) Cost Factor. is claimed to be reduced and in a public cloud delivery model capital expenditure is converted to operational expenditure. This is purported to lower barriers to entry, as infrastructure is typically provided by a third-party and does not need to be purchased for one-time or infrequent intensive computing tasks. Pricing on a utility computing basis is fine-grained with usage-based options and fewer IT skills are required for implementation (in-house).
5 (d) Device and Location Independence. It enables users to access systems using a web browser regardless of their location or what device they are using (e.g., PC, mobile phone). As infrastructure is off-site (typically provided by a thirdparty) and accessed via the Internet, users can connect from anywhere. (e) Virtualization Technology. It allows servers and storage devices to be shared and utilization be increased. Applications can be easily migrated from one physical server to another. (f) Multi-Tenancy. It enables sharing of resources and costs across a large pool of users thus allowing for Centralization of infrastructure in locations with lower costs (such as real estate, electricity, etc.), Peek load capacity increases (users need not engineer for highest possible load-levels), Utilization and efficiency improvements for systems that are often only 10 20% utilised. (g) Reliability. It is improved if multiple redundant sites are used, which makes well-designed cloud computing suitable for business continuity and disaster recovery. (h) Scalability and Elasticity. Scalability and elasticity via dynamic ("ondemand") provisioning of resources on a fine-grained, self-service basis near realtime, without users having to engineer for peak loads. (j) Performance. Performance is monitored, and consistent and loosely coupled architectures are constructed using web services as the system interface. (k) Security. Security could improve due to centralization of data, increased security-focused resources, etc., but concerns can persist about loss of control over certain sensitive data, and the lack of security for stored kernels. Security is often as good as or better than other traditional systems, in part because providers are able to devote resources to solving security issues that many customers cannot afford. However, the complexity of security is greatly increased when data is distributed over a wider area or greater number of devices and in multi-tenant systems that are being shared by unrelated users. In addition, user access to security audit logs may be difficult or impossible. Private cloud installations are in part motivated by users' desire to retain control over the infrastructure and avoid losing control of information security. (l) Maintenance. 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. Similarities 10. Cloud computing shares characteristics with:-
6 (a) Autonomic Computing. Computer systems that are capable of selfmanagement. (b) Client-Server Model. Client server computing refers broadly to any distributed application that distinguishes between service providers (servers) and service requesters (clients). (c) Grid Computing. It is a form of distributed and parallel computing whereby a Super and Virtual Computer is composed of a cluster of networked, loosely coupled computers acting in concert to perform very large tasks. (d) Mainframe Computer. Powerful computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, police and secret intelligence services, enterprise resource planning, and financial transaction processing. (e) Utility Computing. The "packaging of computing resources, such as computation and storage, as a metered service similar to a traditional public utility, such as electricity. (f) Peer-to-Peer. It is a distributed architecture without the need for central coordination, with participants being at the same time both suppliers and consumers of resources (in contrast to the traditional client server model). (g) Cloud Gaming. Also known as on-demand gaming, this is a way of delivering games to computers. The gaming data will be stored in the provider's server, so that gaming will be independent of client computers used to play the game. Cloud Computing Deployment Models 11. There are various different models of Cloud computing. These are explained in following paragraphs:- (a) Public Cloud. Public cloud applications, storage, and other resources are made available to the general public by a service provider. These services are free or offered on a pay-per-use model. Generally, public cloud service providers like Amazon AWS, Microsoft and Google own and operate the infrastructure and offer access only via Internet (direct connectivity is not offered). (b) Community Cloud. It shares infrastructure between several organizations from a specific community with common concerns (security, compliance, jurisdiction, etc.), whether managed internally or by a third-party and hosted internally or externally. The costs are spread over fewer users than a public cloud (but more than a private cloud), so only some of the cost savings potential of cloud computing are realized.
7 (c) Hybrid Cloud. Hybrid cloud is a composition of two or more clouds (private, community or public) that remain unique entities but are bound together, offering the benefits of multiple deployment models. By utilizing "hybrid cloud" architecture, companies and individuals are able to obtain degrees of fault tolerance combined with locally immediate usability without dependency on internet connectivity. Hybrid cloud architecture requires both on-premises resources and off-site (remote) server-based cloud infrastructure. Hybrid clouds lack the flexibility, security and certainty of in-house applications. Hybrid cloud provides the flexibility of in house applications with the fault tolerance and scalability of cloud based services. (d) Private Cloud. It is cloud infrastructure operated solely for a single organization, whether managed internally or by a third-party and hosted internally or externally. Undertaking a private cloud project requires a significant level and degree of engagement to virtualize the business environment and it will require the organization to re-evaluate decisions about existing resources. When it is done right, it can have a positive impact on a business, but every one of the steps in the project raises security issues that must be addressed in order to avoid serious vulnerabilities. Cloud Architecture 12. Systems architecture of the software systems involved in the delivery of cloud computing, typically involves multiple cloud components communicating with each other over a loose coupling mechanism such as a messaging queue. Elastic provision implies intelligence in the use of tight or loose coupling as applied to mechanisms such as these and others. (a) Inter-Cloud. The Inter-cloud is an interconnected global "cloud of clouds" and an extension of the Internet "network of networks" on which it is based. (b) Cloud Engineering. It is the application of engineering disciplines to cloud computing. It brings a systematic approach to the high-level concerns of commercialisation, standardisation, and governance in conceiving, developing, operating and maintaining cloud computing systems. It is a multidisciplinary method encompassing contributions from diverse areas such as systems, software, web, performance, information, security, platform, risk and quality engineering. SECURITY 13. The information housed on the cloud is often seen as valuable to individuals with malicious intent. There is a lot of personal information and potentially secure data that people store on their computers and this information is now being transferred to the cloud. This makes it critical for us to understand the security measures that our cloud provider has in place and it is equally important to take personal precautions to secure your data.
8 14. The first thing we must look into is the security measures that our cloud provider already has in place. These vary from provider to provider and among the various types of clouds. What encryption methods do the providers have in place? What methods of protection do they have in place for the actual hardware that our data will be stored on? Will they have backups of my data? Do they have firewalls set up? If we have a community cloud, what barriers are in place to keep our information separate from other companies? 15. Many cloud providers have standard terms and conditions that may answer these questions but the home user will probably have little negotiation room in their cloud contract. A small business user may have slightly more room to discuss the terms of their contract with the provider and will be able to ask these questions during that time. There are many questions that you can ask, but it is important to choose a cloud provider that considers the security of our data as a major concern. 16. No matter how careful we are with our personal data, by subscribing to the cloud we will be giving up some control to an external source. This distance between we and the physical location of our data creates a barrier. It may also create more space for a third party to access our information. However, to take advantage of the benefits of the cloud, we will have to knowingly give up direct control of your data. On the converse, keep in mind that most cloud providers will have a great deal of knowledge on how to keep your data safe. A provider likely has more resources and expertise than the average user to secure their computers and networks. CONCLUSION 17. To summarize, the cloud provides many options for the everyday computer user as well as large and small businesses. It opens up the world of computing to a broader range of uses and increases the ease of use by giving access through any internet connection. However, with this increased ease also come drawbacks. We have less control over who has access to our information and little to no knowledge of where it is stored. We also must be aware of the security risks of having data stored on the cloud. The cloud is a big target for malicious individuals and may have disadvantages because it can be accessed through an unsecured internet connection. 18. If we are considering using the cloud, we need to be certain that what information we will be putting out in the cloud who will have access to that information and what we will need to make sure it is protected. Additionally, know our options in terms of what type of cloud will be best for our needs, what type of provider will be most useful to us and what the reputation and responsibilities of the providers we are considering are before we sign up. 19. Cloud computing relies on sharing of resources to achieve coherence and economies of scale similar to a utility (like the electricity grid) over a network. At the foundation of cloud computing is the broader concept of converged infrastructure and shared services. x x