UNIT I - INTRODUCTION

Introduction to Cloud Computing - Understanding Cloud Computing - Developing Cloud Services - A Simple Model of the Cloud - Infrastructure as a Service -Platform as a Service - Software as a Service.

INTRODUCTION TO CLOUD COMPUTING

When you store your photos online instead of on your home computer, or use webmail or a social networking site, you are using a “cloud computing” service. If you are an organization, and you want to use, for example, an online invoicing service instead of updating the in-house one you have been using for many years, that online invoicing service is a “cloud computing” service. Cloud computing refers to the delivery of computing resources over the Internet. Instead of keeping data on your own hard drive or updating applications for your needs, you use a service over the Internet, at another location, to store your information or use its applications. Doing so may give rise to certain privacy implications.

Cloud computing is a computing paradigm, where a large pool of systems are connected in private or public networks, to provide dynamically scalable infrastructure for application, data and file storage. With the advent of this technology, the cost of computation, application hosting, content storage and delivery is reduced significantly. Cloud computing is a practical approach to experience direct cost benefits and it has the potential to transform a data center from a capital-intensive set up to a variable priced environment. The idea of cloud computing is based on a very fundamental principal of „reusability of IT capabilities'. The difference that cloud computing brings compared to traditional concepts of “grid computing”, “distributed computing”, “utility computing”, or “autonomic computing” is to broaden horizons across organizational boundaries. Forrester defines cloud computing as: “A pool of abstracted, highly scalable, and managed compute infrastructure capable of hosting end customer applications and billed by consumption.”

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

WHY CLOUD SERVICES ARE SO POPULAR?

Cloud services are popular because they can reduce the cost and complexity of owning and operating computers and networks. Since cloud users do not have to invest in information technology infrastructure, purchase hardware, or buy software licences, the benefits are low up-front costs, rapid return on investment, rapid deployment, customization, flexible use, and solutions that can make use of new innovations. In addition, cloud providers that have specialized in a particular area (such as e-mail) can bring advanced services that a single company might not be able to afford or develop. Some other benefits to users include scalability, reliability, and efficiency. Scalability means that cloud computing offers unlimited processing and storage capacity. The cloud is reliable in that it enables access to applications and documents anywhere in the world via the Internet. Cloud computing is often considered efficient because it allows organizations to free up resources to focus on innovation and product development. Another potential benefit is that personal information may be better protected in the cloud. Specifically, cloud computing may improve efforts to build privacy protection into technology from the start and the use of better security mechanisms. Cloud computing will enable more flexible IT acquisition and improvements, which may permit adjustments to procedures based on the sensitivity of the data. Widespread use of the cloud may also encourage open standards for cloud computing that will establish baseline data security features common across different services and providers. Cloud computing may also allow for better audit trails. In addition, information in the cloud is not as easily lost (when compared to the paper documents or hard drives, for example).

With traditional desktop computing, we run copies of software programs on our own computer. The documents we create are stored on our own pc. Although documents can be accessed from other computers on the network, they can’t be accessed by computers outside the network. This is PC-centric.With cloud computing, the software programs one use aren’t run from one’s personal computer, but are rather stored on servers accessed via the Internet.

If a computer crashes, the software is still available for others to use. Same goes for the documents one create; they’re stored on a collection of servers accessed via the Internet. Anyone with permission can not only access the documents, but can also edit and collaborate on those documents in real time. Unlike traditional computing, this cloud computing model isn’t PC-centric, it’s document-centric.

History

Concept evolved in 1950(IBM) called RJE (Remote Job Entry Process).

In 2006 Amazon provided First public cloud AWS(Amazon Web Service).

The origin of the term cloud computing is unclear. The expression cloud is commonly used in science to describe a large agglomeration of objects that visually appear from a distance as a cloud and describes any set of things whose details are not inspected further in a given context. Another explanation is that the old programs to draw network schematics surrounded the icons for servers with a circle, and a cluster of servers in a network diagram had several overlapping circles, which resembled a cloud.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

In analogy to above usage the word cloud was used as a metaphor for the Internet and a standardized cloud-like shape was used to denote a network on telephony schematics and later to depict the Internet in computer network diagrams. With this simplification, the implication is that the specifics of how the end points of a network are connected are not relevant for the purposes of understanding the diagram. The cloud symbol was used to represent the Internet as early as 1994, in which servers were then shown connected to, but external to, the cloud.

Definition of Cloud Computing Wikipedia

A computing paradigm shift where computing is moved away from personal computers or an individual application server to a "cloud" of computers .

The NIST Definition of Cloud Computing

• Cloud computing is a model for enabling ubiquitous, 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. This cloud model is composed of five essential characteristics, three service models, and four deployment models.

• Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over the Internet.

• In computer networking , cloud computing is a phrase used to describe a variety of computing concepts. Distributed computing on internet.

• Cloud computing is a type of computing that relies on sharing computing resources rather than having local servers or personal devices to handle applications.

• In cloud computing, the word cloud (also phrased as "the cloud") is used as a metaphor for "the Internet," so the phrase cloud computing means "a type of Internet-based computing," where different services such as servers, storage and applications are delivered to an organization's computers and devices through the Internet.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

EVOLUTION OF CLOUD COMPUTING

Cloud computing is the result of evolution and adoption of existing technologies and paradigms. The goal of cloud computing is to allow users to take benefit from all of these technologies, without the need for deep knowledge about or expertise with each one of them. The cloud aims to cut costs, and helps the users focus on their core business instead of being impeded by IT obstacles.

The main enabling technology for cloud computing is virtualization. Virtualization software separates a physical computing device into one or more "virtual" devices, each of which can be easily used and managed to perform computing tasks. With operating system–level virtualization essentially creating a scalable system of multiple independent computing devices, idle computing resources can be allocated and used more efficiently. Virtualization provides the agility required to speed up IT operations, and reduces cost by increasing infrastructure utilization. Autonomic computing automates the process through which the user can provision resources on-demand. By minimizing user involvement, automation speeds up the process, reduces labor costs and reduces the possibility of human errors.

Users routinely face difficult business problems. Cloud computing adopts concepts from Service-oriented Architecture (SOA) that can help the user break these problems intoservices that can be integrated to provide a solution. Cloud computing provides all of its resources as services, and makes use of the well-established standards and best practices gained in the domain of SOA to allow global and easy access to cloud services in a standardized way.

Cloud computing also leverages concepts from utility computing to provide metrics for the services used. Such metrics are at the core of the public cloud pay-per-use models. In addition, measured

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

services are an essential part of the feedback loop in autonomic computing, allowing services to scale on-demand and to perform automatic failure recovery.

Cloud computing is a kind of grid computing; it has evolved by addressing the QoS (quality of service) and reliability problems. Cloud computing provides the tools and technologies to build data/compute intensive parallel applications with much more affordable prices compared to traditional parallel computing techniques.

Cloud computing shares characteristics with:

Client–server model — Client–server computing refers broadly to any distributed application that distinguishes between service providers (servers) and service requestors (clients).

Grid computing — "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."

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.

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."

Peer-to-peer — A distributed architecture without the need for central coordination. Participants are both suppliers and consumers of resources (in contrast to the traditional client–server model)

Cloud Components

It has three components 1.) Client computers2.) Distributed Servers3.) Datacenters

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

Clients

Clients are the device that the end user interact with cloud. three types of clients:

1.) Mobile2.) Thick3.) Thin (Most Popular)

Datacenter

It is collection of servers where application is placed and is accessed via internet.

Distributed servers

Often servers are in geographically different places, but server acts as if they are working next to each other

Central Server

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

It Administers the system such as monitoring traffic, client demands to ensure everything runs smoothly.

It uses a special type of software called Middleware. Middleware allow computer to communicate each other

Individual users connect to the cloud from their own personal computers or portable devices, over the Internet. To these individual users, the cloud is seen as a single application, device, or document.

The hardware in the cloud (and the operating system that manages the hardware connections) is invisible.

Traditional Software Cloud computing vs Cloud computing

ESSENTIAL CHARACTERISTICS OF CLOUD COMPUTING:

On-demand self-service. A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service provider.

Broad network access. Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, tablets, laptops, and workstations).

Resource pooling. The provider’s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacenter). Examples of resources include storage, processing, memory, and network bandwidth.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

Rapid elasticity. Capabilities can be elastically provisioned and released, in some cases automatically, to scale rapidly outward and inward commensurate with demand. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be appropriated in any quantity at any time.

Measured service. Cloud systems automatically control and optimize resource use by leveraging a metering capability1 at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service.

CLOUD COMPUTING BENEFITS

Enterprises would need to align their applications, so as to exploit the architecture models that Cloud Computing offers. Some of the typical benefits are listed below:

1. Reduced Cost There are a number of reasons to attribute Cloud technology with lower costs. The billing model is pay as per usage; the infrastructure is not purchased thus lowering maintenance. Initial expense and recurring expenses are much lower than traditional computing.

2. Increased Storage With the massive Infrastructure that is offered by Cloud providers today, storage & maintenance of large volumes of data is a reality. Sudden workload spikes are also managed effectively & efficiently, since the cloud can scale dynamically.

3. Flexibility This is an extremely important characteristic. With enterprises having to adapt, even more rapidly, to changing business conditions, speed to deliver is critical. Cloud computing stresses on getting applications to market very quickly, by using the most appropriate building blocks necessary for deployment.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

CLOUD COMPUTING CHALLENGES

Despite its growing influence, concerns regarding cloud computing still remain. In our opinion, the benefits outweigh the drawbacks and the model is worth exploring.

Some common challenges are:

1. Data Protection Data Security is a crucial element that warrants scrutiny. Enterprises are reluctant to buy an assurance of business data security from vendors. They fear losing data to competition and the data confidentiality of consumers. In many instances, the actual storage location is not disclosed, adding onto the security concerns of enterprises. In the existing models, firewalls across data centers (owned by enterprises) protect this sensitive information. In the cloud model, Service providers are responsible for maintaining data security and enterprises would have to rely on them

2. Data Recovery and Availability All business applications have Service level agreements that are stringently followed. Operational teams play a key role in management of service level agreements and runtime governance of applications. In production environments, operational teams support Appropriate clustering and Fail over Data Replication System monitoring (Transactions monitoring, logs monitoring and others) Maintenance (Runtime Governance) Disaster recovery Capacity and performance management If, any of the above mentioned services is under-served by a cloud provider, the damage & impact could be severe.

3. Management Capabilities Despite there being multiple cloud providers, the management of platform and infrastructure is still in its infancy. Features like „Auto-scaling‟ for example, are a crucial

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

requirement for many enterprises. There is huge potential to improve on the scalability and load balancing features provided today.

4. Regulatory and Compliance Restrictions In some of the European countries, Government regulations do not allow customer's personal information and other sensitive information to be physically located outside the state or country. In order to meet such requirements, cloud providers need to setup a data center or a storage site exclusively within the country to comply with regulations. Having such an infrastructure may not always be feasible and is a big challenge for cloud providers.

With cloud computing, the action moves to the interface — that is, to the interface between service suppliers and multiple groups of service consumers. Cloud services will demand expertise in distributed services, procurement, risk assessment and service negotiation — areas that many enterprises are only modestly equipped to handle.

DISADVANTAGES OF CLOUD COMPUTING

• Requires a constant Internet connection• Does not work well with low-speed connections• Features might be limited

CLOUD SERVICE MODELS

Service Models are the reference models on which the Cloud Computing is based. These can be categorized into three basic service models:

Cloud Computing Models Cloud Providers offer services that can be grouped into three categories. 1. Software as a Service (SaaS): In this model, a complete application is offered to the customer, as a service on demand. A single instance of the service runs on the cloud & multiple end users are serviced. On the customers‟ side, there is no need for upfront investment in servers or software licenses, while for the provider, the costs are lowered, since only a single application needs to be hosted & maintained. Today SaaS is offered by companies such as Google, Salesforce, Microsoft, Zoho, etc. 2. Platform as a Service (Paas): Here, a layer of software, or development environment is encapsulated & offered as a service, upon which other higher levels of service can be built. The customer has the freedom to build his own applications, which run on the provider‟s infrastructure. To meet manageability and scalability requirements of the applications, PaaS providers offer a predefined combination of OS and application servers, such as LAMP platform (Linux, Apache, MySql and PHP), restricted J2EE, Ruby etc. Google‟s App Engine, Force.com, etc are some of the popular PaaS examples. 3. Infrastructure as a Service (Iaas): IaaS provides basic storage and computing capabilities as standardized services over the network. Servers, storage systems, networking equipment, data centre space etc. are pooled and made available to handle workloads. The customer would typically deploy his own software on the infrastructure. Some common examples are Amazon, GoGrid, 3 Tera, etc.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

There are mainly 3 service models given as:

1. Software as a Service (SaaS)

2. Platform as a Service (PaaS)

3. Infrastructure as a Service (IaaS)

SAAS : SOFTWARE AS A SERVICE

Defined as service-on-demand, where a provider will license software tailored.

In the SaaS model, cloud providers install and operate application software in the cloud and cloud users access the software from cloud clients. Cloud users do not manage the cloud infrastructure and platform where the application runs. This eliminates the need to install and run the application on the cloud user's own computers, which simplifies maintenance and support.

In the business model using software as a service (SaaS), users are provided access to application software and databases. Cloud providers manage the infrastructure and platforms that run the applications. SaaS is sometimes referred to as "on-demand software" and is usually priced on a pay-per-use basis or using a subscription fee.

In the SaaS model, cloud providers install and operate application software in the cloud and cloud Cloud applications are different from other applications in their scalability—which can be achieved by cloning Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

tasks onto multiple virtual machines at run-time to meet changing work demand.Load balancers distribute the work over the set of virtual machines. 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 multitenant, that is, any machine serves more than one cloud user organization.

The pricing model for SaaS applications is typically a monthly or yearly flat fee per user,so price is scalable and adjustable if users are added or removed at any point.

Proponents claim SaaS allows a business the potential to reduce IT operational costs by outsourcing hardware and software maintenance and support to the cloud provider. This enables the business to reallocate IT operations costs away from hardware/software spending and personnel expenses, towards meeting other goals. In addition, with applications hosted centrally, updates can be released without the need for users to install new software. One drawback of SaaS is that the users' data are stored on the cloud provider's server. As a result, there could be unauthorized access to the data. For this reason, users are increasingly adopting intelligent third-party key management systems to help secure their data

Examples of SaaS include: Google Apps, Microsoft Office 365, Onlive, GT Nexus, Marketo, and TradeCard.

SAAS ADVANTAGE

Free or Paid via Subscription

Accessible from any computer

Facilitates collaborative working

The growing use of web-based user interfaces by applications, along with the proliferation of associated practices (e.g., web design), continuously decreased the need for traditional client-server applications. Consequently, traditional software vendor's investment in software based on fat clients has become a disadvantage (mandating ongoing support), opening the door for new software vendors offering a user experience perceived as more "modern".

The standardization of web page technologies (HTML, JavaScript, CSS), the increasing popularity of web development as a practice, and the introduction and ubiquity of web application frameworks like Ruby on Rails or Laravel (PHP) gradually reduced the cost of developing new SaaS solutions, and enabled new solution providers to come up with competitive solutions, challenging traditional vendors.

The increasing penetration of broadband Internet access enabled remote centrally hosted applications to offer speed comparable to on-premises software.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

The standardization of the HTTPS protocol as part of the web stack provided universally available lightweight security that is sufficient for most everyday applications.

The introduction and wide acceptance of lightweight integration protocols such as REST and SOAP enabled affordable integration between SaaS applications (residing in the cloud) with internal applications over wide area networks and with other SaaS applications.

SAAS DISADVANTAGE

Some limitations slow down the acceptance of SaaS and prohibit it from being used in some cases:

Since data are being stored on the vendor’s servers, data security becomes an issue.

SaaS applications are hosted in the cloud, far away from the application users. This introduces

latency into the environment; so, for example, the SaaS model is not suitable for applications that demand response times in the milliseconds.

Multi-tenant architectures, which drive cost efficiency for SaaS solution providers, limit customization of applications for large clients, inhibiting such applications from being used in scenarios (applicable mostly to large enterprises) for which such customization is necessary.

Some business applications require access to or integration with customer's current data. When such data are large in volume or sensitive (e.g., end users' personal information), integrating them with remotely hosted software can be costly or risky, or can conflict with data governance regulations.

Constitutional search/seizure warrant laws do not protect all forms of SaaS dynamically stored data. The end result is that a link is added to the chain of security where access to the data, and, by extension, misuse of these data, are limited only by the assumed honesty of 3rd parties or government agencies able to access the data on their own recognizance. [21][22][23][24]

Switching SaaS vendors may involve the slow and difficult task of transferring very large data files over the Internet.

Organizations that adopt SaaS may find they are forced into adopting new versions, which might result in unforeseen training costs or an increase in probability that a user might make an error.

Relying on an Internet connection means that data are transferred to and from a SaaS firm at Internet speeds, rather than the potentially higher speeds of a firm’s internal network. [25]

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

The standard model also has limitations:

Compatibility with hardware, other software, and operating systems.[26]

Licensing and compliance problems (unauthorized copies of the software program putting the organization at risk of fines or litigation).

Maintenance, support, and patch revision processes.

Can the SaaS hosting company guarantee the uptime level agreed in the SLA (Service Level Agreement)?

PAAS: PLATFORM AS A SERVICE

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.

Platform as a service (PaaS) is a category of cloud computing services that provides a platform allowing customers to develop, run and manage Web applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.PaaS can be delivered in two ways: as a public cloud service from a provider, where the consumer controls software deployment and configuration settings, and the provider provides the networks, servers, storage and other services to host the consumer's application; or as software installed in private data centers or public infrastructure as a service and managed by internal IT departments.

The original intent of PaaS was to simplify the code-writing process for developers, with the infrastructure and operations handled by the PaaS provider. Originally, all PaaSes were in the public cloud. Because many companies did not want to have everything in the public cloud, private and hybrid PaaS options (managed by internal IT departments) were created.

PaaS provides an environment for developers and companies to create, host and deploy applications, saving developers from the complexities of the infrastructure side (setting up, configuring and managing elements such as servers and databases). PaaS can improve the speed of developing an app, and allow the consumer to focus on the application itself. With PaaS, the consumer manages applications and data, while the provider (in public PaaS) or IT department (in private PaaS) manages runtime, middleware, operating system, virtualization, servers, storage and networking. Development tools provided by the vendor are customized according to the needs of the user. The user can choose to maintain the software, or have the vendor maintain it.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

PaaS offerings may also include facilities for application design, application development, testing and deployment, as well as services such as team collaboration, web service integration, and marshalling, database integration, security, scalability, storage, persistence, state management, application versioning, application instrumentation, and developer community facilitation. Besides the service engineering aspects, PaaS offerings include mechanisms for service management, such as monitoring, workflow management, discovery and reservation.

Examples of PaaS include: AWS Elastic Beanstalk, Cloud Foundry, Heroku, Force.com, EngineYard, Mendix, OpenShift, Google App Engine, Windows Azure Cloud Services and OrangeScape

ADAVANTAGE & DISADVANTAGE OF PAAS

The advantages to PaaS are primarily that it allows for higher-level programming with dramatically reduced complexity; the overall development of the application can be more effective, as it has built-in infrastructure; and maintenance and enhancement of the application is easier. It can also be useful in situations where multiple developers are working on a single project involving parties who are not located nearby.

The primary disadvantage would be the possibility of being locked in to a certain platform. However, most PaaSes are relatively lock-in free

IAAS: INFRASTRUCTURE AS A SERVICE

In the most basic cloud-service model, providers of IaaS offer computers physical or (more often) virtual machines and other resources. IaaS clouds often offer additional resources such as a virtual-machine disk image library, raw (block) and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles.IaaS-cloud providers supply these resources on-demand from their large pools installed in data centers.

In the most basic cloud-service model & according to the IETF (Internet Engineering Task Force), providers of IaaS offer computers – physical or (more often) virtual machines – and other resources. (A hypervisor, such as Xen, Oracle VirtualBox, KVM, VMware ESX/ESXi, or Hyper-V runs the virtual machines as guests. Pools of hypervisors within the cloud operational support-system can support large numbers of virtual machines and the ability to scale services up and down according to customers' varying requirements.) IaaS clouds often offer additional resources such as a virtual-machine disk image library, raw block storage, and file or object storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles.[52] IaaS-cloud providers supply these resources on-demand from their large pools installed in data centers. For wide-area connectivity, customers can use either the Internet or carrier clouds (dedicated virtual private networks).

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

To deploy their applications, cloud users install operating-system images and their application software on the cloud infrastructure. In this model, the cloud user patches and maintains the operating systems and the application software. Cloud providers typically bill IaaS services on a utility computing basis: cost reflects the amount of resources allocated and consumed

Examples of IaaS providers include: Amazon EC2, Azure Services Platform, DynDNS, Google Compute Engine, HP Cloud, iland, Joyent, LeaseWeb, Linode, NaviSite, Oracle Infrastructure as a Service, Rackspace Cloud , ReadySpace Cloud Services , ReliaCloud, SAVVIS, SingleHop, and Terremark

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

DEPLOYMENT MODELS:

Deployment models define the type of access to the cloud. These are:

Understanding Public and Private Clouds Enterprises can choose to deploy applications on Public, Private or Hybrid clouds. Cloud Integrators can play a vital part in determining the right cloud path for each organization. Public Cloud Public clouds are owned and operated by third parties; they deliver superior economies of scale to customers, as the infrastructure costs are spread among a mix of users, giving each individual client an attractive low-cost, “Pay-as-you-go” model. All customers share the same infrastructure pool with limited configuration, security protections, and availability variances. These are managed and supported by the cloud provider. One of the advantages of a Public cloud is that they may be larger than an enterprises cloud, thus providing the ability to scale seamlessly, on demand. Private Cloud Private clouds are built exclusively for a single enterprise. They aim to address concerns on data security and offer greater control, which is typically lacking in a public cloud. There are two variations to a private cloud: - On-premise Private Cloud: On-premise private clouds, also known as internal clouds are hosted within one‟s own data center. This model provides a more standardized process and protection, but is limited in aspects of size and scalability. IT departments would also need to incur the capital and operational costs for the physical resources. This is best suited for applications which require complete control and configurability of the infrastructure and security. - Externally hosted Private Cloud: This type of private cloud is hosted externally with a cloud provider, where the provider facilitates an Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

exclusive cloud environment with full guarantee of privacy. This is best suited for enterprises that don‟t prefer a public cloud due to sharing of physical resources. Hybrid Cloud Hybrid Clouds combine both public and private cloud models. With a Hybrid Cloud, service providers can utilize 3rd party Cloud Providers in a full or partial manner thus increasing the flexibility of computing. The Hybrid cloud environment is capable of providing on-demand, externally provisioned scale. The ability to augment a private cloud with the resources of a public cloud can be used to manage any unexpected surges in workload.

PRIVATE CLOUD.

The cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (e.g., business units). It may be owned, managed, and operated by the organization, a third party, or some combination of them, and it may exist on or off premises.

COMMUNITY CLOUD.

The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises.

PUBLIC CLOUD.

The cloud infrastructure is provisioned for open use by the general public. It may be owned, managed, and operated by a business, academic, or government organization, or some combination of them. It exists on the premises of the cloud provider.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

HYBRID CLOUD.

The cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds).

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

COMPARING PUBLIC, PRIVATE, AND HYBRID CLOUD COMPUTING OPTIONS

PUBLIC CLOUD VS PRIVATE CLOUD Public cloud is used as a service via Internet by the users, whereas a private cloud, as the name

conveys is deployed within certain boundaries like firewall settings and is completely managed and monitored by the users working on it in an organization.

Users have to pay a monthly bill for public cloud services, but in private cloud money is charged on the basis of per Gb usage along with bandwidth transfer fees.

Public cloud functions on the prime principle of storage demand scalability, which means it requires no hardware device. On the contrary, no hardware is required even in private cloud, but the data stored in the private cloud can only be shared amongst users of an organization and third party

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

sharing depends upon trust they build with them. It is also entirely monitored by the business entity where it is running.

Cloud computing comes in three forms: public clouds, private clouds, and hybrids clouds. Depending on the type of data you're working with, you'll want to compare public, private, and hybrid clouds in terms of the different levels of security and management required.

PUBLIC CLOUDSA public cloud is one in which the services and infrastructure are provided off-site over the Internet. These clouds offer the greatest level of efficiency in shared resources; however, they are also more vulnerable than private clouds. A public cloud is the obvious choice whenMs.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

Your standardized workload for applications is used by lots of people, such as e-mail.

You need to test and develop application code.

You have SaaS (Software as a Service) applications from a vendor who has a well-implemented

security strategy.

You need incremental capacity (the ability to add computer capacity for peak times).

You’re doing collaboration projects.

You’re doing an ad-hoc software development project using a Platform as a Service (PaaS)

offering cloud.

Public clouds are owned and operated by third-party service providers. Customers benefit from economies of scale because infrastructure costs are spread across all users, thus allowing each individual client to operate on a low-cost, “pay-as-you-go” model. Another advantage of public cloud infrastructures is that they are typically larger in scale than an in-house enterprise cloud, which provides clients with seamless, on-demand scalability.

It is also important to note that all customers on public clouds share the same infrastructure pool with limited configurations, security protections and availability variances, as these factors are wholly managed and supported by the service provider.

Many IT department executives are concerned about public cloud security and reliability. Take extra time to ensure that you have security and governance issues well planned, or the short-term cost savings could turn into a long-term nightmare.

PRIVATE CLOUDSPrivate clouds are those that are built exclusively for an individual enterprise. They allow the firm to host applications in the cloud, while addressing concerns regarding data security and control, which is often lacking in a public cloud environment. There are two variations of private clouds:

On-Premise Private Cloud: This format, also known as an “internal cloud,” is hosted within an organization’s own data center. It provides a more standardized process and protection, but is often limited in size and scalability. Also, a firm’s IT department would incur the capital and operational costs for the physical resources with this model. On-premise private clouds are best used for applications that require complete control and configurability of the infrastructure and security.

Externally-Hosted Private Cloud: This private cloud model is hosted by an external cloud computing provider (such as Eze Castle Integration). The service provider facilitates an exclusive cloud environment with full guarantee of privacy. This format is recommended for organizations that prefer not to use a public cloud infrastructure due to the risks associated with the sharing of physical resources.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

The following graphic shows the difference between customer private clouds and provider private clouds.

A private cloud is one in which the services and infrastructure are maintained on a private network. These clouds offer the greatest level of security and control, but they require the company to still purchase and maintain all the software and infrastructure, which reduces the cost savings. A private cloud is the obvious choice when Your business is your data and your applications. Therefore, control and security are paramount. Your business is part of an industry that must conform to strict security and data privacy issues. Your company is large enough to run a next generation cloud data center efficiently and effectively on its own.

To complicate things, the lines between private and public clouds are blurring. For example, some public cloud companies are now offering private versions of their public clouds. Some companies that only offered private cloud technologies are now offering public versions of those same capabilities.

HYBRID CLOUDS

Hybrid clouds combine the advantages of both the public and private cloud models. In a hybrid cloud, a company can leverage third-party cloud providers in either a full or partial manner. This increases the flexibility of computing. The hybrid cloud environment is also capable of providing on-demand, externally-provisioned scalability. Augmenting a traditional private cloud with the resources of a public cloud can be used to manage any unexpected surges in workload.

A hybrid cloud includes a variety of public and private options with multiple providers. By spreading things out over a hybrid cloud, you keep each aspect at your business in the most efficient environment possible. The downside is that you have to keep track of multiple different security platforms and ensure that all aspects of your business can communicate with each other. Here are a couple of situations where a hybrid environment is best.

Your company wants to use a SaaS application but is concerned about security. Your SaaS vendor can create a private cloud just for your company inside their firewall. They provide you with a virtual private network (VPN) for additional security.

Your company offers services that are tailored for different vertical markets. You can use a public cloud to interact with the clients but keep their data secured within a private cloud.

The management requirements of cloud computing become much more complex when you need to manage private, public, and traditional data centers all together. You'll need to add capabilities for federating these environments.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

CLOUD ARCHITECTURE, MODELING AND DESIGN

Cloud Adoption Lifecycle Model: Role of Cloud Modeling and ArchitectureThe Cloud Adoption Lifecycle Model offers an idealized set of stages that should ensure a thorough cloud planning, modeling, and deployment process for your enterprise. Key to success with cloud is the process of modeling and architecture. The cloud modeling and architecture process involves the following activities:

Cloud Modeling. Determining, mapping, and alignment of business drivers and key requirements to the range of potential cloud technical and resource patterns available. Cloud modeling forces the explicit definition of business needs, and then establishing what cloud technical patterns and resource models best suit those business requirements. For example,a business need for a customer relationship management (CRM) application provided as a service (by Salesforce.com)

Cloud Deployment Model. Determining, based on the cloud modeling effort, what cloud deployment model(s) best fit your organization’s business and technical needs. Is an internal/

private cloud best for your current and pending needs, or are their third-party external cloud service providers that can satisfy your business requirements. (e.g., Amazon S3, EC2, or Salesforce Force.com)

Cloud Architecture. Once the above choices have been made, the cloud architecture can be defined, which is important for all cloud deployment scenarios: internal/private, external/ public, hybrid/integrated, and community/semi-private.Cloud architecture must be defined, documented, governed,and managed regardless of whether you are planning a purely internal

private cloud or if you intend to leverage external public clouds. the requirements are to develop a robust cloud architecture, document it, and evaluate and test it—all prior to deploying that architecture.

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CLOUD INDUSTRY STANDARDS

Cloud interoperability and integration standards, covering cloud to-cloud (C2C) integration, hybrid-to-private cloud integration,and interoperability of various cloud patterns with one

another. Cloud interface standards and application programmer interfaces (APIs) to facilitate the

consumption of cloud to support specific business requirements, standardize the access to and invocation of cloud computing, and more.

Cloud discovery, portability, onboarding and offboarding models, and cloud provider abstraction to enable seamless switching of cloud providers without disrupting business operations.

Cloud performance benchmarks to guide consumers on how cloud can increase asset utilization, resource optimization, and other performance guides, as well as pricing model standardization

of various a la carte cloud models (e.g., comparing Amazon’s web services to other cloud service and solution providers).

Cloud governance standards for design-time planning, architecture, modelling, and deployment, as well as run-time standards for management, monitoring, operations and support, quality of service (QoS), and service level agreements (SLAs).

Cloud security and privacy concerns, such as data integrity, physical and logical security, and all other related security requirements for services, applications, and interactions in a cloud ecosystem.

Cloud standards for various tiers of cloud enablement, such as virtualization vendor-neutral frameworks driven by standards organizations such as Organization for the Advancement of Structured Information Standards (OASIS), the Object Management Group (OMG), and others, typically for the overall betterment of the industry.

Below are summaries of certain industry standards bodies and organizations working to develop cloud industry standards:

National Institute of Standards and Technology NIST is heavily focused on federal government cloud standards, including emphasis on cloud interfaces, cloud integration, and cloud APIs. NIST has a working definition of cloud computing, as well as a forthcoming special publication that will cover cloud architectures, security, and deployment strategies for the federal government.

Open Cloud Consortium. The Open Cloud Consortium (OCC) is a recent standards group comprised of a group of universities focused on improving performance of various cloud patterns— primarily computing and storage cloud patterns—across geographically distributed data centers. In addition, the OCC seeks open frameworks to enable cloud integration and interoperability across multiple vendors, benchmarks for cloud, open source reference implementations of cloud, as well as managing a testing sandbox for cloud computing, called the Open Cloud Testbed.

Cloud Computing Interoperability Forum. The Cloud Computing Interoperability Forum (CCIF) is focused on establishing a global cloud community and ecosystem where organizations can work together to foster and enable wider adoption of cloud computing technology, solutions, and services. The CCIF’s UCI will be an open and standardized interface to facilitate the unification of all cloud APIs to support cloud integration and interoperability.

Distributed Management Task Force. The Distributed Management Task Force (DMTF) is focused on developing standards for cloud management and operations across cloud and enterprise platforms. In addition, DMTF has a draft standard for System Virtualization,

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Partitioning, and Clustering. DMTF has also initiated the DMTF Open Cloud Standards Incubator to accelerate development of open cloud standards.

Cloud Computing Community and Cloud Standards WikisThe cloud computing community and cloud standards wikis have been excellent resources to see the state of the industry with respect to cloud standards, as well as concepts for developing a Cloud Computing Reference Model, cloud computing stack, and cloud platform reference architecture.These industry grass roots efforts also have contributed two additional items of value to the cloud ecosystem: the Cloud Computing Manifesto for cloud providers, and the Cloud Computing Bill of Rights for end-users or consumers of cloud computing solutions.

Cloud Computing Manifesto. The Cloud Computing Manifesto (CCMF) is a set of principles and guidelines developed for the cloud providers’ community as complementary guidance to the Cloud Computing Bill of Rights. Categories of information included in the manifesto are user-centric guidelines, philanthropic principles, openness, transparency, interoperability,representation, discrimination, evolution, balance, and security.

Cloud Computing Bill of Rights. The Cloud Computing Bill of Rights (CC-BoR) is a set of rights developed in support of end-users of cloud computing solutions and services.

Cloud Security Alliance. The Cloud Security Alliance is focused on promoting the development and use of best practices for cloud security, as well as providing education on how cloud-enabled security can benefit other computing models and architectures.

Standards Monitoring FrameworkIndustry standards fall into three broad categories, as illustrated in Exhibit 6.2.

Appropriate care should be taken when evaluating cloud computing for our enterprise, so that we do not inadvertently leverage the wrong standards or immature standards, and thus expose our enterprise to unnecessary risk and cost. Determine what standards matter to our particular cloud requirements, and the subsequent cloud model, cloud deployment pattern, and cloud architecture.

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University

A Cloud Computing Reference ModelThe components of this Cloud Computing Reference Model are summarized below, and are explained in detail in the subsequent sections.Cloud Enablement Model

Cloud virtualization tier Cloud operating system tier Cloud platform tier Cloud business tier

Cloud Deployment Model Internal/private cloud External/public cloud Hybrid/integrated cloud Community/vertical/shared by community of interest stakeholders

Cloud Governance and Operations Model Governance, culture, and behavior Security and privacy Management and monitoring Operations and support

Cloud Ecosystem Model Cloud network/dial tone Cloud ecosystem enablement Cloud consumers and cloud providers Cloud physical access, integration, and distribution

The Cloud Computing Reference Model is depicted in Exhibit 6.3.

EXPLORING THE CLOUD COMPUTING LOGICAL ARCHITECTURE

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One widely-adopted cloud reference architecture is provided by NIST. The NIST cloud reference architecture is a high-level model comprised of three ‘‘tiers’’ of cloud capabilities ‘‘as a Service.’’ In this NIST model, illustrated in Exhibit 6.4, there are three categories of cloud—Infrastructure, Platform, and Software—all ‘‘as a Service’’ architectures.

Exhibit 6.5 offers an extended cloud computing logical architecture that broadens the tiers and logical layers of cloud computing.

This model includes the following eight virtualized capabilities in support of attaining cloudcomputing:1.Network virtualization (NaaS)2.Infrastructure Virtualization (IaaS)3.Application hosting virtualization (Container aaS)

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4.Platform virtualization (PaaS)5.Data virtualization (DaaS)6.Application virtualization (SaaS)7.SOA/Services virtualization (SOAaaS)8.Governance virtualization (GaaS)

Another view of a cloud logical stack is illustrated in Exhibit 6.6.Available from the Cloud Computing Community Wiki, this cloud stack is comprised of six layers or tiers as shown.

Exhibit 6.6 Logical Cloud Stack: Six Tiers

Exhibit 6.5 considers storage, computing, network, and security virtualization as part of the infrastructure virtualization tier. In addition, the cloud stack of Exhibit 6.6 also includes the cloud clients tier.

Developing a Holistic Cloud Computing Reference ModelThe Cloud Enablement Model is illustrated in Exhibit 6.7.The Cloud Enablement Model is comprised of five fundamental tiers of Cloud functionality, working from the bottom up, and listed below:

Exhibit 6.7 Cloud Enablement Model Tiers1. Cloud Physical Tier. Provides the physical computing, storage, network, and security resources that are virtualized and cloud enabled to support cloud requirements.

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2. Cloud Virtualization Tier. Provides core physical hardware virtualization and provides a potentially useful (in certain situations) foundation for cloud computing.

3. Cloud Operating System Tier. Provides the cloud computing ‘‘fabric,’’ as well as application virtualization, core cloud provisioning, metering, billing, load balancing, workflow, and related functionality typical of cloud platforms.4.Cloud Platform Tier. Provides the technical solutions, application and messaging middleware, application servers, et cetera that comprise cloud- and/or application platforms, as well as pre-integrated cloud- and application platforms themselves, offered via PaaS delivery models.

5.Cloud Business Tier. Comprises the business or mission exploitation of cloud-enabled business applications, software, data, content, knowledge, and associated analysis frameworks.

Before we develop the detailed descriptions of the four primary tiers of the Cloud Enablement Model, there are a few principles and guidelines that must be explained first. The following rules are appropriate to make use of this Cloud Computing Reference Model.

Cloud Tiers Enable Higher-Level Tiers. Each cloud tier, working from the bottom up in the Cloud Computing Reference Model, enables the cloud tier or tiers above it. The tiers build upon one another, but yet are independent and offer separately accessible cloud capabilities in and of themselves.

Cloud Tiers Are Individually ‘‘Atomic’’ and Individually Accessible. Cloud consumers can access and consume cloud enabled resources directly from any of these tiers, independent of the others, via cloud API and a portal or self-service user interface of some fashion.

All Cloud Tiers Need Ecosystem Enablement and Cloud DialTone. Each cloud tier must have the necessary cloud network/dial tone and cloud ecosystem enablement capabilities in order to be discoverable, provisionable, and consumable as a service via the cloud.

Cloud Consumer-Provider Continuum: Finally, implied in our Cloud Computing Reference Model is a continuum that describes the relationship of cloud providers to cloud consumers. We represent this continuum as three categories: CloudFoundation, Cloud Enablement, and Cloud Exploitation.

The four elements of the Cloud Enablement Model are explained in detail in the sections below.Cloud Virtualization Tier (Infrastructure as a Service) Typical physical resources included in the cloud virtualization tier include:

Computing resources. Storage resources. Network resources. Security resources. Other physical infrastructure resources that may be virtualized and provided as

foundational cloud infrastructure enablement capabilities.

Cloud Operating System Tier

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The functionality of this layer includes the types of capabilities listed below: Virtualization technology SOA enablement technology Billing and metering Chargeback and financial integration Load balancing and performance assurance Monitoring, management, and SLA enforcement Resource provisioning and management Onboarding and offboarding automation Security and privacy tools/controls Cloud pattern enablement tools (see Exhibit 6.6) Cloud workflow, process management, and orchestration tools

Cloud Platform Tier (Platform Enablement and Platforms Provided as a Service)

Figure 6.8 depicts the cloud platform tier as two sub-tiers: the Cloud Platform Middleware sub-tier, and the Cloud Platform sub-tier. The Cloud Platform Middleware Sub-tier includes all the cloud and application middleware technologies and tools typically needed to build an application platform, e.g. SOA platform middleware, application servers, messaging and application middleware, web servers, runtime application containers, content servers, developer tools and integrated development environments (IDEs) typically associated with application servers, et al.

The Cloud Platform/PaaS Sub-tier represented as the upper portion of the Cloud Platform Tier represents pre-integrated cloud and application platforms, which can be offered as a service PaaS) as a standalone, virtualized application capability such as Force.com,Google App Engine, etc.

The cloud platform is what enables Platform as a Service. The following capabilities are included in this cloud tier:

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PaaS as pre-assembled, integrated application platforms provided to others (e.g., Google App Engine, Salesforce’s Force.com)

SOA middleware, services and other related SOA enablement middleware and capabilities.

Application container services, application servers, and related application hosting and runtime services.

Web application and content servers, content hosting and delivery, and web server capabilities.

Messaging, mediation, integration, and related messaging services and middleware, provided as part of an application platform, as a service. This would also include event engines, complex event processing and related event middleware.

Developer resources to support develop on boarding, application development, testing resources, sandbox functionality, and application provisioning, hosting, and the related application metering, billing, and support capabilities.

Cloud Business Tier

The cloud business tier includes the following business capabilities, provided as services, to end-user consumers:

SaaS, including business applications, enterprise applications,desktop software, business utilities (e-mail, calendar, synchronization), portal, and so forth.

DaaS/KaaS Business processes as a Service KaaS Anything aaS

Ms.Krishnaveni S,Assistant Professor,Software Engineering,SRM University