Essential Characteristics, Service & Deployment Models of Cloud Computing

This Presentation covers the Five Characteristics, Four Deployment Models and Three Service Models (5-4-3 Rule) of Cloud Computing Architecture

Essential Characteristics of Cloud Computing

• As per the definition of NIST, cloud model is composed of five essential characteristics,four deployment models and three service models.
• Here is the description of those essential characteristics of Cloud Computing:

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1. On-demand self-service: Consumers have the ability to independently and automatically provision computing resources—such as server time and network storage—without the need for direct human intervention with the service provider.
1. This capability exemplifies the on-demand nature and elasticity of cloud services.
2. Examples of resources available on the cloud include storage, processing, memory, and network bandwidth.

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Essential Charcteristics of CC (2)

2. Broad network access: Cloud resources are accessible via network connections using standard protocols and interfaces, which facilitate their use across diverse client devices, including mobile phones, laptops, and PDAs.

• This approach ensures broad compatibility and interoperability among heterogeneous platforms, supporting varied client environments

Essential Characteristics of CC (3)

3. Elastic resource pooling: The provider’s computing resources are pooled to serve multiple consumers using a multitenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand.

• There is a sense of location independence in accessing the cloud
• The customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify the location at a higher level of abstraction (e.g., country, state, or data center).

Essential Charcteristics of CC (4)

4. Rapid elasticity: Capabilities can be rapidly and elastically provisioned, in some cases automatically, to quickly scale out and rapidly released to quickly scale in.

• To the consumer, the capabilities available for provisioning often appear to be unlimited and can be purchased in any quantity at any time.

Essential Characterisitics of CC (5)

5. Measured service: Cloud systems automatically control and optimize resource use by leveraging a metering capability 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

Four Deployment Models of Cloud Computing

• Deployment models describe the ways with which the cloud services can be deployed or made available to its customers
• The physical location of the cloud (internet)-based computing resources is determined based on the deployment model
• It determines the location where data and services are acquired and provisioned to its customers
• Four deployment models are available for the deployment of cloud services namely public, private, community and hybrid cloud services

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Private Cloud

• In Private Cloud model, the cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (e.g., business units)
• The infrastructure 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

Public Cloud

• In this model of cloud deployment, the cloud infrastructure is provisioned for open use by the general public
• Public cloud may be owned, managed, and operated by a business, academic, or government organization, or some combination of them.
• The public cloud exists only on the premises of the cloud provider such as AWS, Google and Microsoft

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Community Cloud

• The cloud infrastructure in the community cloud is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy and compliance considerations)
• It may be managed by the organizations or a third party and may exist on premise or off premise

Hybrid Cloud

• The cloud infrastructure of hybrid cloud is a composition of two or more distinct cloud infrastructures (private, public or community) that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability

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Three Delivery Models of CC

• A service in general is a transaction between a provider, who will offer the service and a consumer, who will use the service.
• As per NIST, there are three possible delivery models of providing the services of cloud computing.. They are:
• Software-as-a-Service (SaaS)
• Platform-as-a-Service (PaaS)
• Infrastructure-as-a-Service (IaaS)

SPI Model of Service Delivery on the Cloud

• Service, Platform and Infrastructure are the three kinds of service with which the cloud-based computing resources

are available to end customers

• The model used for service delivery on the cloud is also known as the Service–Platform–Infrastructure (SPI) model of the cloud and is shown in the Figure

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SPI - Software, Platform and Infrastructure services

• SaaS is a software distribution model in which applications (software, which is one of the most important computing resources) are hosted by a vendor or service provider and made available to customers over a network, typically the Internet.
• PaaS is a paradigm for delivering operating systems and associated services (e.g., computer aided software engineering [CASE] tools, integrated development environments [IDEs] for developing software solutions) over the Internet without downloads or installation.
• IaaS involves outsourcing the equipment used to support operations, including storage, hardware, servers, and networking components.

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Software as a Service (SaaS)

• According to NIST, Software-as-a-Service (SaaS) is defined as follows:
• “SaaS is the service provided to the consumer to access the provider’s applications running on a cloud infrastructure.
• SaaS applications are accessible from various client devices through either a thin client interface, such as a web browser (e.g., web-based email), or a program interface.
• The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user specific application configuration settings.”

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Software as a Service (2)

• Software-as-a-Service (SaaS) refers to applications that are available on the cloud on-demand basis.
• It enables the consumer with the capability to use the provider’s applications running on a cloud infrastructure.
• Consumers can easily access the applications running in the cloud using any device at their ends.
• SaaS offers software as it is and does not have an opportunity of customization based on the users requirement.
• Typical applications offered as a service include Customer Relationship Management (CRM), business intelligence analytics, and online accounting software.

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Software as a Service (3)

• From the perspective of the consumer, the SaaS model has the following benefits:
• No infrastructure cost
• No upfront cost of buying any software
• Administration is simple and easy
• All the updates are taken care of by the service provider
• Performance guarantee by the provider
• In case multiple users are collaborating, versions would not be a problem; hence, collaboration is easy
• Since it is hosted in cloud, it is accessible from anywhere through the
• Internet.
• Rapid implementation
• Standalone and configurable applications
• Subscription and pay-as-you-go (PAYG) pricing

Platform as a Service (PaaS)

• The capability provided to the customer in this delivery model of PaaS is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages, libraries, services and tools supported by the provider
• The consumer does not manage or control the underlying cloud infrastructure but has control over the deployed applications and possibly configure the application-hosting environment
• PaaS acts as a ready-to-run development or operating framework for the developers to deploy their developed software on the cloud

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Platform as a Service (2)

• The role of the service provider of PaaS is to provide the networks, servers, and storage and manages the levels of scalability and security of those resources on the cloud
• The cloud user on the other hand typically pays for the platform services used for developing and deploying software on the cloud
• Examples of PaaS include Google App Engine and Microsoft Azure

Infrastructure as a Service (IaaS)

• The capability provided to the customer of IaaS is to provision hardware resources such as processing, storage, networks, and other fundamental computing resources on a pay-per-use basis
• The user of IaaS has the ability to deploy and run arbitrary software, which include Operating Systems and Applications
• The consumers of IaaS can’t manage or control the underlying infrastructure on IaaS, instead they have the control over the platform (OS), storage, and applications deployed on the infrastructure
• IaaS also provides limited control over selected network components such as firewalls

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Infrastructure as a Service (2)

• The service provider of IaaS owns the equipment and is responsible for housing, cooling operation, and maintenance of infrastructure resource provided on IaaS
• Amazon Web Services (AWS) is a popular example of a large IaaS provider
• The major difference between PaaS and IaaS is the amount of control that users have over the resources available on the cloud platform
• PaaS allows vendors to manage everything on the cloud, while IaaS requires more managemet form the customer side.

Review Questions

1. Is it true that all essential characteristic features of the cloud are necessary to completely describe it?
2. What are the service offering models of the cloud?
3. What are the deployment models of the cloud?
4. What are the actors and their roles in a typical cloud ecosystem?
5. Enlist and explain the requirements that need to be considered for
6. cloud services.
7. Explain how a cloud application is being accessed.
8. Give a brief note on the merits and demerits of cloud computing.

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