What is Cloud Computing? Cloud Computing: Understanding How It Works and Its Benefits.

What is Cloud Computing?

Cloud Computing is a general term used to describe a new class of network based computing that takes place over the Internet, basically a step on from Utility Computing  a collection/group of integrated and networked hardware, software and Internet infrastructure (called a platform). Using the Internet for communication and transport provides hardware, software and networking services to clients.

A model for providing on-demand internet access to a shared pool of processing resources, including servers, storage, databases, applications, and services, is known as cloud computing. It makes it possible for users to access and utilize these resources without needing to make sizable upfront expenditures in hardware, software, or infrastructure.

Cloud Summary:- Cloud computing is an umbrella term used to refer to Internet based development and services In a cloud computing environment, third-party providers who run and maintain sizable data centers with enormous processing capacity host and manage the computing resources. Users can use a web browser or a software program to access these resources, and they usually only pay for what they use on a per-use basis. In comparison to conventional on-premises processing models, cloud computing has a number of advantages. Depending on their needs, it enables companies to scale up or down their computing resources.. A number of characteristics define cloud data, applications services and infrastructure: 

1. Remotely hosted: Services or data are hosted on remote infrastructure.
2. Ubiquitous: Services or data are available from anywhere. 
3. Commodified: The result is a utility computing model similar to traditional that of traditional utilities, like gas and electricity - you pay for what you would want! 

Cloud Architecture :- The design and arrangement of the different parts and technologies that make up a cloud computing infrastructure is referred to as cloud architecture. In order to establish a pool of computing resources that can be dynamically allocated to satisfy the varying needs of users and applications, virtualization technologies are used.

The hardware layer, the virtualization layer, the management layer, and the application layer are common layers in cloud design. The physical infrastructure that supplies the computing tools, including servers, storage, and networking hardware, makes up the hardware layer. Virtual machines that can be assigned to users and apps are created by the virtualization layer using software to abstract hardware resources. The management layer offers the instruments and services required for cloud control.

Cloud Computing Characteristics:

• 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.
• 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 Service Models:- Cloud service models refer to the different ways in which cloud computing services are delivered to users. The three primary cloud service models are Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). IaaS provides virtualized computing resources, PaaS provides a platform for application development and deployment, while SaaS delivers software applications over the internet on a subscription basis. Each model offers varying levels of control, flexibility, and responsibility for the user.

Cloud service models are the different ways in which cloud computing services are delivered to users. There are three primary cloud service models:

Software as a Service (SaaS):- Consumers purchase the ability to access and use an application or service that is hosted in the cloud. A benchmark example of this is Salesforce.com, as discussed previously, where necessary information for the interaction between the consumer and 

the service is hosted as part of the service in the cloud.

Also, Microsoft has made a significant investment in this area, and as part of the cloud computing option for Microsoft® Office 365, its Office suite 

is available as a subscription through its cloud-based Online Services.

Platform as a Service (PaaS):- This model provides users with a platform on which they can develop, run, and manage their own applications without having to worry about the underlying infrastructure. The platform provides a set of tools and services for developers to build and deploy their applications. Consumers purchase access to the platforms, enabling them to deploy their own software and applications in the cloud. The operating systems and network access are not managed by the consumer, and there might be constraints as to which applications can be deployed.

Examples include Amazon Web Services (AWS), Rackspace and Microsoft Azure.

Infrastructure as a Service (IaaS):-  This model provides users with access to virtualized computing resources such as servers, storage, and networking. With IaaS, users can create and manage their own virtual machines, install their own operating systems, and run their own software applications.

Consumers control and manage the systems in terms of the operating systems, applications, storage, and network connectivity, but do not themselves control the cloud infrastructure.

What is the purpose and benefits?

Cloud computing enables companies and applications, which are system infrastructure dependent, to be infrastructure-less. By using the Cloud infrastructure on “pay as used and on demand”, all of us can save in capital and operational investment!

Clients can:

• Put their data on the platform instead of on their own desktop PCs and/or on their own servers.
• They can put their applications on the cloud and use the servers within the cloud to do processing and data manipulations etc. 

Cloud-Sourcing

• Why is it becoming a Big Deal:

1. Using high-scale/low-cost providers,
2. Any time/place access via web browser,
3. Rapid scalability; incremental cost and load sharing,
4. Can forget need to focus on local IT.

• Concerns:

1. Performance, reliability, and SLAs,
2. Control of data, and service parameters,
3. Application features and choices,
4. Interaction between Cloud providers,
5. No standard API – mix of SOAP and REST!
6. Privacy, security, compliance, trust…

Some Commercial Cloud Offerings

There are several commercial cloud offerings available in the market, some of the most popular ones are:

• Amazon Web Services (AWS)
• Microsoft Azure:
• Google Cloud Platform (GCP)
• IBM Cloud
• Oracle Cloud Infrastructure (OCI)
• Alibaba Cloud: 

Cloud Taxonomy

Opportunities and Challenges

Advantages of Cloud Computing

• Lower computer costs: 

• You do not need a high-powered and high-priced computer to run cloud computing's web-based applications. 

• Since applications run in the cloud, not on the desktop PC, your desktop PC does not need the processing power or hard disk space demanded by traditional desktop software. 

• When you are using web-based applications, your PC can be less expensive, with a smaller hard disk, less memory, more efficient processor... 

• In fact, your PC in this scenario does not even need a CD or DVD drive, as no software programs have to be loaded and no document files need to be saved.

• Improved performance:

• With few large programs hogging your computer's memory, you will see better performance from your PC. 

• Computers in a cloud computing system boot and run faster because they have fewer programs and processes loaded into memory…

• Reduced software costs: 

• Instead of purchasing expensive software applications, you can get most of what you need for free-ish!

• most cloud computing applications today, such as the Google Docs suite.

• better than paying for similar commercial software

• which alone may be justification for switching to cloud applications.

• Instant software updates:

• Another advantage to cloud computing is that you are no longer faced with choosing between obsolete software and high upgrade costs

• When the application is web-based, updates happen automatically 

• available the next time you log into the cloud. 

• When you access a web-based application, you get the latest version 

• without needing to pay for or download an upgrade.

• Improved document format compatibility. 

• You do not have to worry about the documents you create on your machine being compatible with other users' applications or OSes

• There are potentially no format incompatibilities when everyone is sharing documents and applications in the cloud.

• Unlimited storage capacity:

• Cloud computing offers virtually limitless storage. 

• Your computer's current 1 Tbyte hard drive is small compared to the hundreds of Pbytes available in the cloud.

• Increased data reliability:

• Unlike desktop computing, in which if a hard disk crashes and destroy all your valuable data, a computer crashing in the cloud should not affect the storage of your data.

• if your personal computer crashes, all your data is still out there in the cloud, still accessible

• In a world where few individual desktop PC users back up their data on a regular basis, cloud computing is a data-safe computing platform!

• Universal document access:

• That is not a problem with cloud computing, because you do not take your documents with you. 

• Instead, they stay in the cloud, and you can access them whenever you have a computer and an Internet connection

• Documents are instantly available from wherever you are

• Latest version availability:

• When you edit a document at home, that edited version is what you see when you access the document at work. 

• The cloud always hosts the latest version of your documents

• as long as you are connected, you are not in danger of having an outdated version

• Easier group collaboration:

• Sharing documents leads directly to better collaboration.

• Many users do this as it is an important advantages of cloud computing

• multiple users can collaborate easily on documents and projects

• Device independence. 

• You are no longer tethered to a single computer or network. 

• Changes to computers, applications and documents follow you through the cloud. 

• Move to a portable device, and your applications and documents are still available.

Disadvantages of Cloud Computing

• Requires a constant Internet connection:

• Cloud computing is impossible if you cannot connect to the Internet. 

• Since you use the Internet to connect to both your applications and documents, if you do not have an Internet connection you cannot access anything, even your own documents. 

• A dead Internet connection means no work and in areas where Internet connections are few or inherently unreliable, this could be a deal-breaker. 

• Does not work well with low-speed connections: 

• Similarly, a low-speed Internet connection, such as that found with dial-up services, makes cloud computing painful at best and often impossible. 

• Web-based applications require a lot of bandwidth to download, as do large documents. 

• Features might be limited:

• This situation is bound to change, but today many web-based applications simply are not as full-featured as their desktop-based applications.

• For example, you can do a lot more with Microsoft PowerPoint than with Google Presentation's web-based offering

• Can be slow:

• Even with a fast connection, web-based applications can sometimes be slower than accessing a similar software program on your desktop PC. 

• Everything about the program, from the interface to the current document, has to be sent back and forth from your computer to the computers in the cloud.

• If the cloud servers happen to be backed up at that moment, or if the Internet is having a slow day, you would not get the instantaneous access you might expect from desktop applications.

•  Stored data might not be secure:

• With cloud computing, all your data is stored on the cloud. 

• The questions is How secure is the cloud? 

• Can unauthorized users gain access to your confidential data? 

• Stored data can be lost:

• Theoretically, data stored in the cloud is safe, replicated across multiple machines. 

• But on the off chance that your data goes missing, you have no physical or local backup. 

• Put simply, relying on the cloud puts you at risk if the cloud lets you down.

•  HPC Systems:

• Not clear that you can run compute-intensive HPC applications that use MPI/OpenMP!

• Scheduling is important with this type of application

• as you want all the VM to be co-located to minimize communication latency!

• General Concerns:

• Each cloud systems uses different protocols and different APIs

• may not be possible to run applications between cloud based systems

• Amazon has created its own DB system (not SQL 92), and workflow system (many popular workflow systems out there)

• so your normal applications will have to be adapted to execute on these platforms.

The Future

• Many of the activities loosely grouped together under cloud computing have already been happening and centralized computing activity is not a new phenomena

• Grid Computing was the last research-led centralized approach

• However there are concerns that the mainstream adoption of cloud computing could cause many problems for users

• Many new open source systems appearing that you can install and run on your local cluster

• should be able to run a variety of applications on these systems

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