Cloud Computing Delivery Models:

Topics:

1. Introduction.

2. Cloud Computing Delivery Models.

3. Attributes of Cloud Computing.

3.1 Virtualization.

3.2 Multi-tenancy.

3.3 Network Access.

3.4 Scalability.

3.5 Metering/Chargeback.

4. Software as a Service (SaaS).

5. Platform as a Service (PaaS).

6. Infrastructure as a Service (IaaS).

7. Comparison of Different Services.

8. Obstacles for Cloud Technology

9. Cloud Vulnerabilities

10. Cloud Challenges

11. Practical Applications of Cloud Computing

12. Summary

Introduction

Cloud Computing is a broad term that describes a broad range of services. Perhaps, that is the reason there is no single, one-size-fits all definition for this term. Instead, depending on what services one is describing or what you are talking to, the moniker term 'cloud' is often described as a stack, as a response to the broad range of services built on top of one another.

v Definition

"Cloud Computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (for an example, network, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction."

Cloud Computing Delivery Models:

Cloud Computing services range from satisfying a single functional need of an organization to delivering the entire data Centre through networks. With Cloud Computing, innovation is accelerated and the opportunity to focus entirely on the core business operations is enhanced.

v Delivery models

v 1. Public cloud

v 2. Private cloud

v 3. Hybrid cloud

Public Cloud

• This utility model of Cloud Computing provides easy access to a shared infrastructure, storages as well as other computing resources.

• These shared resources are hosted in a remote Data Centre, and multiple clients can gain access to them using the internet.

• Scalability and cost-effectiveness are

the major advantages of a public cloud.

Private Cloud

Provisioning of infrastructure for controlled access by a single organization providing controlled access to restricted data and information for a new organizations in a closed network format is referred to as private cloud.

All business units within the organization can access the cloud without having to build their own infrastructure.

Hybrid Cloud

As the name implies, a cloud that is a combination of two or more clouds (public cloud, private cloud or community cloud) is called as hybrid cloud. In a hybrid cloud environment, workloads can be moved between private and the public clouds based on changing computing needs and costs. This allows enhanced flexibility and more options when it comes to data deployment.

Community Cloud

• A community cloud is a type of cloud primarily used by a closed group of people or organizations.

• It is a collaborative efforts, and the hardware infrastructure is mutually shared by two or more organizations from a specific community.

• It could either be managed or hosted internally within an organizations in the community or by a third party cloud service provider.

• The infrastructure costs are shared among the community members based on mutual agreements.

Attributes of Cloud Computing

When a company decides to move its one or more IT services to the cloud, it incurs many benefits, including lower capital costs, potentially lower operating costs, better support for mobile and remote personnel, and IT flexibility.

v Virtualization

Virtualization forms the core of cloud technology. It refers to the creation of virtual servers, memory, operating system or a storage device as opposed to the actual existence of the resource. In simpler terms, virtualization allows one physical computer to run several virtual machines at the same time.

v Multi-tenancy

Multi-tenancy, a key common attribute of both private and public clouds, applies to all three services of the cloud (SaaS, PaaS and IaaS). Consider an example of a cloud service provider offering storage and backup solutions in the cloud. Organizations that access these cloud resources are called tenants, and the fact that many such tenants access these common resources gives rise to the concept of multi-tenancy.

v Network Access

No cloud can exist without a network. Network facilitate the sharing for resources, movement of data and integrated functioning of the infrastructure components. The services to be offered over the internet or private networks

are allowed by network access.

v Scalability

One of the strongest effects of Cloud Computing on a business is the scalability of IT resources. The business environment today suffers from increasing levels of unpredictability and shrinking IT budget.

v Metering/Chargeback

Metering or Chargeback in the cloud ecosystem is the type of payment structure through which user can gain unlimited access to all computing resources and yet pay for only their actual usage. This allows the cutting down of excess costs that are usually termed as IT overhead costs.

Infrastructure as a Service (IaaS)

Infrastructure as a Service forms the base of the Cloud Computing stacks. The service offers the ability to provision server, storage, networking and other basic computing infrastructure resources through the internet and as required. Since the IaaS cloud delivery model eliminates the need to invest in hardware, it is a perfect solution for startup and for organizations that deal with extreme spikes and troughs in usage.

Platform as a Service (PaaS)

PaaS is the best fit for organizations that are committed to the delivery of web and mobile applications within a stipulated time and budget. A PaaS provider offers the toolkit to build an application and the virtual machine to run it. Application developers can design the functionalities as well as the interface based on their particular needs.

Software as a Service (PaaS)

Software as a Service (SaaS) allows an organization to access the desired software applications through the cloud on a subscription basis. The SaaS vender offers access to the software applications with no upfront investment and takes care of all upgrades.

Comparison of Different Services

The "cloud" has become a universal buzzword, and all types of organizations are looking at driving the benefits of the cloud. The first step towards migrating to the cloud is to understand the three service-delivery models, their capabilities and limitations

Obstacles for Cloud Technology

Like with any other technology, there are some significant obstacles to be overcome in cloud computing too before it can turn into a part of the mainstream operations in an organization. Common concerns that arise while choosing to adopt the cloud are:

v Data security and privacy issues: Moving to the cloud means loss of control over applications an data to third party provider, thus issues related to security and privacy are inevitable.

v Adherence to regulatory and compliance measures: Data in the cloud may be stored in a different location for better performance and to avoid localised outages. In such cases, apart from the industry-specific regulations, location-specific compliance measures must also be met.

v Vendor lock-in: A robust SLA must be established to avoid too much dependence on the cloud service provider.

v Lack of performance and uptime: Will your application perform better in the cloud? Is your cloud service provider promising the maximum uptime? These issues must be addressed before moving to the cloud.

v Network connectivity and bandwidth: Cloud Computing experts additional pressure on the internet used by the organization, and bandwidth requirements must be evaluated based on the service used.

v Dependency on outside agency: The involvement of a third party into the internal operations of an enterprise may sometime cause psychological obstacles for CIOs and IT managers.

v Knowledge and integration: Cloud migration process must be done through a well structured procedure which will be explained in detail in the upcoming chapters. With Cloud Computing, the IT department must be prepared to embrace the changes in their roles and responsibilities.

Cloud Vulnerabilities:

Cloud Vulnerabilities can be defined as a weakness in any part of the cloud environment and can be used by a potential attacker for personal gain. Some common Vulnerabilities are:

v Session riding: When attackers use the information form cookies to perform data theft or any similar cyber crime, it is referred to as session riding. Tricking users into sending authenticated requests to fake websites another form of this vulnerability.

v Virtual Machine Escape: Any vulnerability in the hypervisor paves the way for potential attacks on the hypervisor as well as for all virtual machines running on top of it. This vulnerability. though rare, still exists and can causes serious damage in the worst cases.

v Reliability and Availability: Availability of the cloud service directly translates to business value for the client. However power outages, technical glitches and natural disasters are some common sources that lead to cloud downtime.

v Insecure Cryptography: Cryptographic algorithms used to generate random numbers must provide a large entropy pool for maximum data protection. In the case of random number generators that offer only a small entropy pool, easily guessable numbers could lead to security issues.

v Data Portability: There may be several reason for an organization to move its data from one cloud service provider to another. Unsatisfying performance, finding a chapter option or the cloud service provider running out of business could be some possible reason.

v Vendor Lock-in: Do you want to be stuck with one single cloud service provider forever? The answer is definitely not, given that the IT needs keep changing for every organization and another provider in the industry may just come up with the most perfect solution for your current needs.

v Internet Dependency: The internet is the unsung hero of the entire cloud setup. An unfailing internet service provider is what an organization needs to achieve 100% success in the cloud.

Cloud Challenges:

Once the decision to embrace the cloud has been taken, organization must chart out a detailed plan that marks their journey to the cloud. Listed below are the top challenges battled in a cloud environment by the cloud vendor, client as well as the end user.

v Keeping up with security requirements: Security tops the list of challenges when it comes to Cloud Computing as organization lose their direct control over data.

v Obtaining the right knowledge and expertise: With the advent of Cloud Computing, the role of the IT department has significant changes and so has their need for knowledge and skills.

v Choosing the right vendor: Partnering with the right vendor is the key to success in the cloud. Organizations must follow a fail-safe mechanism in evaluating potential cloud vendors and ensure that they meet all security and privacy standards.

v Data interoperability and portability: Organizations expand with time and their needs change rapidly. Therefore, additional caution must be practiced to avoid choosing a platform/technology/provider that makes the organization too dependent on them.

v Budgeting difficulties while moving to the cloud: The very nature of cloud is that it is scalable and is delivered on demand. This, in turn, may cause difficulties while drawing IT budgets for that entire organization.

Practical Applications of Cloud Computing:

v Resource-hungry applications: Applications that demand many resources like the CPU, memory, storage or time can be hosted on the cloud efficiently.

v Application with extreme spikes and troughs: Consider the example of an HR system that is accessed by employees only a few times in a year. However, on the review day, every employees in the organization logs onto the system thus slowing the system.

v Special Server Configuration: When applications demand non-standard settings, the cloud server is a much easier option to be configured to perfectly fit the requirements.

v Backup and Recovery: This is most common application of cloud as it is clearly more expensive to manage the entire duplicate infrastructure.

Summary:

ü The three categories of cloud services, Software as a Service (SaaS), Platform as a Service (PaaS) and Infrastructure as a Service (IaaS) together form the Cloud Computing stack.

ü Software as a Service (SaaS) allows an organization to access the desired software applications through the cloud on a subscription basis.

ü The PaaS model of Cloud Computing enables organization to access the toolkit to build the software application and the virtual machine to run it.

ü IaaS is the ability to provision server, storage, networking and other basic computing resources through the internet as and when required.

ü The key attributes of a Cloud Computing environment are virtualization, multi-tenancy, networking access scalability and metering/chargeback.

ü Implementing the cloud paves the way for some challenges like privacy and security concerns, low quality of service, and loss of control and so on. The key lies in choosing a reliable cloud service vendor and establishing strong SLAs.

ü Though all kinds of web applications can be hosted on the cloud, applications with special server configuration, varying levels of utilization and resources-hungry application are the most suitable candidates for the cloud.

ü ICICI Lombard, WhatsApp and Expedia are great stories that exemplify the power of cloud in today's business world.

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