Cloud Computing and Its Applications

Cloud Computing is the delivery of computing services such as servers, storage, databases, networking, software, analytics, intelligence, and more, over the Cloud (Internet). Cloud Computing provides an alternative to the on-premises datacentre. With an on-premises datacentre, we have to manage everything, such as purchasing and installing hardware, virtualization, installing the operating system, and any other required applications, setting up the network, configuring the firewall, and setting up storage for data. After doing all the set-up, we become responsible for maintaining it through its entire lifecycle. But if we choose Cloud Computing, a cloud vendor is responsible for the hardware purchase and maintenance. They also provide a wide variety of software and platform as a service. We can take any required services on rent. The cloud computing services will be charged based on usage. The cloud environment provides an easily accessible online portal that makes handy for the user to manage the compute, storage, network, and application resources. Some cloud service providers are in the following figure.

In 1969, Leonard Kleinrock, one of the chief scientists of the original Advanced Research Projects Agency Network (ARPANET), which seeded the Internet, said: “As of now, computer networks are still in their infancy, but as they grow up and become sophisti- cated, we will probably see the spread of ‘computer utilities’ which, like present electric and telephone utilities, will service individual homes and offices across the country.” Cloud computing allows renting infrastructure, runtime environments, and services on a pay-per- use basis. This principle finds several practical applications and then gives different images of cloud computing to different people. Chief information and technology officers of large enterprises see opportunities for scaling their infrastructure on demand and sizing it according to their business needs. End users leveraging cloud computing services can access their documents and data anytime,anywhere, and from any device connected to the Internet. Many other points of view exist. One of the most diffuse views of cloud computing can be summarized as follows: “I don’t care where my servers are, who manages them, where my documents are stored, or where my applications are hosted. I just want them always available and access them from any device connected through Internet. And I am willing to pay for this service for as a long as I need it.”

Cloud computing has some interesting characteristics that bring benefits to both cloud service consumers (CSCs) and cloud service providers (CSPs). These characteristics are:

• No up-front commitments
• On-demand access
• Nice pricing
• Simplified application acceleration and scalability
• Efficient resource allocation
• Energy efficiency
• Seamless creation and use of third-party services

The most evident benefit from the use of cloud computing systems and technologies is the increased economical return due to the reduced maintenance costs and operational costs related to IT software and infrastructure. This is mainly because IT assets, namely software and infrastructure, are turned into utility costs, which are paid for as long as they are used, not paid for up front. IT infrastructure and software generated capital costs, since they were paid up front so that business start-ups could afford a computing infrastructure, enabling the business activities of the organization. The revenue of the business is then utilized to compensate over time for these costs. End users can benefit from cloud computing by having their data and the capability of operating on it always available, from anywhere, at any time, and through multiple devices. Information and services stored in the cloud are exposed to users by Web-based interfaces that make them accessible from portable devices as well as desktops at home.

Cloud computing is the delivery of different services through the Internet. These resources include tools and applications like data storage, servers, databases, networking, and software. Rather than keeping files on a proprietary hard drive or local storage device, cloud-based storage makes it possible to save them to a remote database. As long as an electronic device has access to the web, it has access to the data and the software programs to run it.
Cloud computing is a popular option for people and businesses for a number of reasons including cost savings, increased productivity, speed and efficiency, performance, and security.

Cloud computing is not a single piece of technology like a microchip or a cellphone. Rather, it is a system primarily comprised of three services: software as a service (SaaS), infrastructure as a service (IaaS), and platform as a service (PaaS).

1. Software as a service - (SaaS) involves the licensure of a software application to customers. Licenses are typically provided through a pay-as-you-go model or on-demand. This type of system can be found in Microsoft Office 365.
2. Infrastructure as a service (IaaS) involves a method for delivering everything from operating systems to servers and storage through IP-based connectivity as part of an on-demand service. Clients can avoid the need to purchase software or servers, and instead procure these resources in an outsourced, on-demand service. Popular examples of the IaaS system include IBM Cloud and Microsoft Azure.
3. Platform as a service (PaaS) is considered the most complex of the three layers of cloud-based computing. PaaS shares some similarities with SaaS, the primary difference being that instead of delivering software online, it is actually a platform for creating software that is delivered via the Internet. This model includes platforms like Salesforce.com and Heroku.

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.

Cloud computing allows anyone with a credit card to provision virtual hardware, runtime environments, and services. These are used for as long as needed, with no up-front commitments required. The entire stack of a computing system is transformed into a collection of utilities, which can be provisioned and composed together to deploy systems in hours rather than days and with virtually no maintenance costs. The long-term vision of cloud computing is that IT services are traded as utilities in an open market, without technological and legal barriers. In this cloud marketplace, cloud service providers and consumers, trading cloud services as utilities, play a central role. Many of the technological elements contributing to this vision already exist. Different stake-holders leverage clouds for a variety of services. The need for ubiquitous storage and compute power on demand is the most common reason to consider cloud computing. A scalable runtime for applications is an attractive option for application and system developers that do not have infrastructure or cannot afford any further expansion of existing infrastructure. This approach provides opportunities for optimizing datacenter facilities and fully utilizing their capabilities to serve multiple users. This consolidation model will reduce the waste of energy and carbon emissions, thus contributing to a greener IT on one end and increasing revenue on the other end.

New, interesting problems and challenges are regularly being posed to the cloud community, including IT practitioners, managers, governments, and regulators. Technical challenges also arise for cloud service providers for the management of large computing infrastructures and the use of virtualization technologies on top of them. Security in terms of confidentiality, secrecy, and protection of data in a cloud environment is another important challenge. Organizations do not own the infrastructure they use to process data and store information. This condition poses challenges for confidential data, which organizations cannot afford to reveal. Legal issues may also arise. These are specifically tied to the ubiquitous nature of cloud computing, which spreads computing infrastructure across diverse geographical locations. Different legislation about privacy in different countries may potentially create disputes as to the rights that third parties (including government agencies) have to your data.

Cloud computing has some interesting characteristics that bring benefits to both cloud service consumers (CSCs) and cloud service providers (CSPs). These characteristics are:

• No up-front commitments
• On-demand access
• Nice pricing
• Simplified application acceleration and scalability
• Efficient resource allocation
• Energy efficiency
• Seamless creation and use of third-party services

The most evident benefit from the use of cloud computing systems and technologies is the increased economical return due to the reduced maintenance costs and operational costs related to IT software and infrastructure. This is mainly because IT assets, namely software and infrastructure, are turned into utility costs, which are paid for as long as they are used, not paid for up front. IT infrastructure and software generated capital costs, since they were paid up front so that business start-ups could afford a computing infrastructure, enabling the business activities of the organization. The revenue of the business is then utilized to compensate over time for these costs. End users can benefit from cloud computing by having their data and the capability of operating on it always available, from anywhere, at any time, and through multiple devices. Information and services stored in the cloud are exposed to users by Web-based interfaces that make them accessible from portable devices as well as desktops at home.

AWS offers comprehensive cloud IaaS services ranging from virtual compute, storage, and networking to complete computing stacks. AWS is mostly known for its compute and storage-on- demand services, namely Elastic Compute Cloud (EC2) and Simple Storage Service (S3). EC2 provides users with customizable virtual hardware that can be used as the base infrastructure for deploying computing systems on the cloud. It is possible to choose from a large variety of virtual hardware configurations, including GPU and cluster instances. EC2 also provides the capability to save a specific running instance as an image, thus allowing users to create their own templates for deploying systems. These templates are stored into S3 that delivers persistent storage on demand. S3 is organized into buckets; these are containers of objects that are stored in binary form and can be enriched with attributes. Users can store objects of any size, from simple files to entire disk images, and have them accessible from everywhere.

Google AppEngine is a scalable runtime environment mostly devoted to executing Web applications. These take advantage of the large computing infrastructure of Google to dynamically scale as the demand varies over time. AppEngine provides both a secure execution environment and a collection of services that simplify the development of scalable and high-performance Web applications. These services include in-memory caching, scalable data store, job queues, messaging, and cron tasks. Developers can build and test applications on their own machines using the AppEngine software development kit (SDK). Once development is complete, developers can easily migrate their application to AppEngine, set quotas to contain the costs generated, and make the application available to the world. The languages currently supported are Python, Java, and Go.

Microsoft Azure is a cloud operating system and a platform for developing applications in the cloud. Applications in Azure are organized around the concept of roles, which identify a distribution unit for applications and embody the application’s logic. Currently, there are three types ofrole: Web role, worker role, and virtual machine role. The Web role is designed to host a Web application, the worker role is a more generic container of applications and can be used to perform workload processing, and the virtual machine role provides a virtual environment in which the computing stack can be fully customized, including the operating systems.

A fundamental characteristic of cloud computing is the capability to deliver, on demand, a variety of IT services that are quite diverse from each other. cloud computing services offerings into three major categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), and Software-as- a-Service (SaaS). These categories are related to each other as described in Figure 1.5, which provides an organic view of cloud computing.At the base of the stack, Infrastructure-as-a-Service solutions deliver infrastructure on demand in the form of virtual hardware, storage, and networking. Virtual hardware is utilized to provide compute on demand in the form of virtual machine instances.Platform-as-a-Service solutions are the next step in the stack. They deliver scalable and elastic runtime environments on demand and host the execution of applications. These services are backed by a core middleware platform that is responsible for creating the abstract environment where applications are deployed and executed. At the top of the stack, Software-as-a-Service solutions provide applications and services on demand. Most of the common functionalities of desktop applications. Each layer provides a different service to users. IaaS solutions are sought by users who want to leverage cloud computing from building dynamically scalable computing systems requiring a spe- cific software stack. IaaS services are therefore used to develop scalable Websites or for back- ground processing.

Popek and Goldberg provided a classification of the instruction set and proposed three theorems that define the properties that hardware instructions need to satisfy in order to efficiently support virtualization. Theorem 1: For any conventional third-generation, a VMM maybe constructed if the set of sensitive instructions for that computer is a set of privileged instructions.This theorem establishes that all the instructions that change the configuration of the system resources should generate a trap in user mode and be executed under the control of the virtual machine manager.

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Theorem 2:A conventional third-generation computer is recursively if:

1. It is virtualizable and
2. A VMM without any timing dependencies can be constructed for it.

Recursive virtualization is the ability to run a virtual machine manager on top of another virtual machine manager. This allows nesting hypervisors as long as the capacity of the underlying resources can accommodate that. Virtualizable hardware is a prerequisite to recursive virtualization.

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THEOREM 3: A hybrid VMM may be constructed for any conventional third-generation machine in which set of user-sensitive instructions is a subset of the set of privileged instructions. There is another term, hybrid virtual machine (HVM), which is less efficient than the virtual machine system. In the case of an HVM, more instructions are interpreted rather than being executed directly. All instructions in virtual supervisor mode are interpreted. Whenever there is an attempt to execute a behavior-sensitive or control-sensitive instruction, HVM controls the execution directly or gains the control via a trap. Here all sensitive instructions are caught by HVM that are simulated.

Development of a cloud computing application happens by leveraging platforms and frameworks that provide different types of services, from the bare-metal infrastructure to customizable applications serving specific purposes.

1. Amazon web services (AWS)
2. Google AppEngine
3. Microsoft Azure
4. Hadoop
5. Force.com and Salesforce.com
6. Manjrasoft Aneka

Machine reference model Modern computing systems can be expressed in terms of the reference model described in below Figure At the bottom layer, the model for the hardware is expressed in terms of the Instruction Set Architecture (ISA), which defines the instruction set for the processor, registers, memory, and interrupt management. ISA is the interface between hardware and software, and it is important to the operating system (OS) developer (System ISA) and developers of applications that directly manage the underlying hardware (User ISA). The application binary interface (ABI) separates the operating system layer from the applications and libraries, which are managed by the OS. ABI covers details such as low-level data types, alignment, and call conventions and defines a format for executable programs. The highest level of abstraction is represented by the application programming interface (API), which interfaces applications to libraries and/or the underlying operating system. a possible implementation features a hierarchy of privileges (see Figure 3.5) in the form of ring-based security: Ring 0, Ring 1, Ring 2, and Ring 3; Ring 0 is in the most privileged level and Ring 3 in the least privileged level. Ring 0 is used by the kernel of the OS, rings 1 and 2 are used by the OS-level services, and Ring 3 is used by the user. Recent systems support only two levels, with Ring 0 for supervisor mode and Ring 3 for user mode.

Advantages of Virtualization

• Managed execution and isolation are perhaps the most important advantages of virtualization.
• allow building secure and controllable computing environments.
• This enables fine tuning of resources, which is important in a server consolidation and is also a requirement for effective quality of service
• Portability especially for execution virtualization techniques
• Java programs are compiled once and run every where. they only require that the java Virtual Machine be installed on the host.
• To achieve a more efficient use of resources the underlying host, without interfering with each other.

Disadvantages of Virtualization

• Performance degradation since virtualization interposes an abstraction layer b/w the guest and the host , the guest can experience increased latencies
• Binary transition and interpretation can slow down the execution of managed applications
• inefficiency and degraded user explain leads to an experience leads to an inefficient use of the host
• Some of the specific features of the host cannot be exposed by the abstraction layer and then become an inaccesible
• Security holes and new threats opens the door to a new and unexpected form of phishing

• In a virtualized environment there are three major components: guest, host, and virtualization layer.
• The guest represents the system component that interacts with the virtualization layer rather than with the host, as would normally happen.
• The host represents the original environment where the guest is supposed to be managed.
• The virtualization layer is responsible for recreating the same or a different environment where the guest will operate
• in the case of hardware virtualization, the guest is represented by a system image Compromising an operating system & installed application
• These are installed on top of Virtual hardware that is controlled & managed by the Virtualization layer also called Virtual machine mangager

Operating System Level Virtualization

• To create different and separated execution environments for applications that are managed concurrently.
• There is no virtual machine manager or hypervisor, and the virtualization is done within a single operating system.
• OS kernel allows for multiple isolated user space instances.
• chroot mechanism in Unix systems. The chroot operation changes the file system root directory for a process and its children to a specific directory.
• The process and its children cannot have access to other portions of the file system.

Programming language-level virtualization

• To achieve ease of deployment of applications, managed execution, and portability across different platforms and operating systems.
• It consists of a virtual machine executing the byte code of a program, which is the result of the compilation process.
• Generally these virtual machines constitute a simplification of the underlying hardware instruction set and provide some high-level instructions that map some of the features of the languages compiled for them.
• Basic Combined Programming Language
• Both Java and the CLI are stack-based virtual machines.

Application-level virtualization

• Such emulation is performed by a thin layer - a program or an operating system component that is in charge of executing the application.
• Interpretation - In this technique every source instruction is interpreted by an emulator for executing native ISA instructions, leading to poor performance.
• Binary translation - In this technique every source instruction is converted to native instructions with equivalent functions. After a block of instructions is translated, it is cached and reused.
• SaaS utilizes application-level virtualization to deploy the application

Virtualization is mainly used to emulate execution environments, storage, and networks. Process-level techniques are implemented on top of an existing operating system, which has full control of the hardware. System-level techniques are implemented directly on hardware and do not require or require a minimum of support from an existing operating system.

Infrastructure as a service (IaaS) is a form of cloud computing that provides virtualized computing resources over the internet. IaaS is one of the three main categories of cloud computing services, alongside software as a service (SaaS) and platform as a service (PaaS). In the IaaS model, the cloud provider manages IT infrastructures such as storage, server and networking resources, and delivers them to subscriber organizations via virtual machines accessible through the internet. IaaS can have many benefits for organizations, such as potentially making workloads faster, easier, more flexible and more cost efficient.

In an IaaS service model, a cloud provider hosts the infrastructure components that are traditionally present in an on-premises data center. This includes servers, storage and networking hardware, as well as the virtualization or hypervisor layer. IaaS providers also supply a range of services to accompany those infrastructure components. These can include the following:

• detailed billing;
• monitoring;
• log access;
• security;
• load balancing;
• clustering; and
• storage resiliency, such as backup, replication and recovery.

These services are increasingly policy-driven, enabling IaaS users to implement greater levels of automation and orchestration for important infrastructure tasks. For example, a user can implement policies to drive load balancing to maintain application availability and performance.

IaaS advantages Organizations choose IaaS because it is often easier, faster and more cost-efficient to operate a workload without having to buy, manage and support the underlying infrastructure. With IaaS, a business can simply rent or lease that infrastructure from another business. IaaS is an effective cloud service model for workloads that are temporary, experimental or that change unexpectedly. For example, if a business is developing a new software product, it might be more cost-effective to host and test the application using an IaaS provider. Once the new software is tested and refined, the business can remove it from the IaaS environment for a more traditional, in-house deployment. Conversely, the business could commit that piece of software to a long-term IaaS deployment if the costs of a long-term commitment are less. In general, IaaS customers pay on a per-user basis, typically by the hour, week or month. Some IaaS providers also charge customers based on the amount of virtual machine space they use. This pay-as-you-go model eliminates the capital expense of deploying in-house hardware and software. When a business cannot use third-party providers, a private cloud built on premises can still offer the control and scalability of IaaS -- though the cost benefits no longer apply.

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IaaS disadvantages Despite its flexible, pay-as-you-go model, IaaS billing can be a problem for some businesses. Cloud billing is extremely granular, and it is broken out to reflect the precise usage of services. It is common for users to experience sticker shock -- or finding costs to be higher than expected -- when reviewing the bills for every resource and service involved in application deployment. Users should monitor their IaaS environments and bills closely to understand how IaaS is being used and to avoid being charged for unauthorized services. Insight is another common problem for IaaS users. Because IaaS providers own the infrastructure, the details of their infrastructure configuration and performance are rarely transparent to IaaS users. This lack of transparency can make systems management and monitoring more difficult for users. IaaS users are also concerned about service resilience. The workload's availability and performance are highly dependent on the provider. If an IaaS provider experiences network bottlenecks or any form of internal or external downtime, the users' workloads will be affected. In addition, because IaaS is a multi-tenant architecture, the noisy neighbor issue can negatively impact users' workloads.

When looking to implement an IaaS product, there are important considerations to make. The IaaS use cases and infrastructure needs should be strictly defined before different technical requirements and providers should be considered. Technical and storage needs to consider for implementing IaaS include:

• Networking. When focusing on cloud deployments, organizations need to ask certain questions to make sure that the provisioned infrastructure in the cloud can be accessed in an efficient manner.
• Storage. Organizations should consider requirements for storage types, required storage performance levels, possible space needed, provisioning and potential options such as object storage.
• Compute. Organizations should consider the implications of different server, VM, CPU and memory options that cloud providers can offer.
• Security. Data security should be of paramount importance when evaluating cloud services and providers. Questions about data encryption, certifications, compliance and regulation, and secure workloads should be pursued in detail.
• Disaster recovery. Disaster recovery features and options are another key value area for organizations in the event of failover on VM, server or site levels.
• Server Size. Options for server and VM sizes, how many CPUs can be placed onto servers, and other CPU and memory details.
• Throughput of the network. Speed between VMs, data centers, storage, and internet.
• General manageability. How many features of the IaaS can the user control, which parts do you need to control and how easy are they to control and manage?

During the implementation process, organizations should closely consider how the technical and service offerings of different providers fulfill business-side needs, as well as the business's own specific usage requirements. The market for IaaS vendors should be carefully evaluated; with considerable variance of capabilities within products, some may better align with business needs than others. Once a vendor and product are decided, it is important to negotiate all service-level agreements. Thorough negotiation with the vendor will make it less likely for your organization to be negatively affected by fine-print details that were previously unknown. Furthermore, an organization should thoroughly assess the capabilities of its IT department to determine how well equipped it is to deal with the ongoing demands of IaaS implementation. In the IaaS model, in-house developers are responsible for the infrastructure's technical maintenance -- including software patches, upgrades and troubleshooting. This personnel assessment is needed to ensure that the organization is equipped to maximize value on all fronts from an IaaS implementation.