Cloud Computing Reference Models: Explanation and Example with Diagrams

Introduction to Cloud Computing Reference Models

The cloud computing reference model is an abstract model that defines cloud terminology and design elements, a set of configuration rules, and a semantic interpretation. Simply put, it divides the cloud into layers, defines the functionality of each, and provides a reference model for cloud computing, allowing users to choose the right model for their specific applications and efficient deployment .

Cloud computing is the most radical innovation of the last decade, providing services like storage, networking, software and analytics at a single click. Targeting a staggering CAGR of 20%, the global cloud computing industry is expected to reach a market size of $2,432.87 billion by 2030, thereby increasing its importance across industries.

Currently, many vendors are providing various services to their customers. This makes it difficult to evaluate each vendor. As cloud adoption is accelerating and the number of vendors is increasing, there is a need to define cloud computing standards to help understand how each vendor works and compare them to each other.

What is the cloud computing reference model? 

The cloud computing reference model is an abstract model that characterizes and standardizes cloud computing environments by dividing them into abstraction layers and cross-layer functionality. This reference model divides cloud computing activities and functions into three cross-layer functions and five logical layers.

Each of these layers describes different things that may exist in a cloud computing environment, such as computing systems, networking, storage devices, virtualization software, security measures, control and management software, and more. It also describes the relationships between these organizations. The five layers are the physical layer, the virtual layer, the control layer, the service orchestration layer, and the service layer.

The Cloud Computing Reference Model is divided into three cross-functional layers:

1. Software as a Service (SaaS)
2. Platform as a Service (PaaS)
3. Infrastructure as a Service (IaaS)

The below diagram explains the cloud computing reference model:

Cloud Computing Reference Model Overview

IaaS, PaaS, and SaaS are the three most popular cloud delivery models, and they are both widely adopted and formalized. A cloud-delivered service model is a specific combination of pre-configured IT resources provided by a cloud service provider. However, each of these three delivery types provides varying degrees of functionality and administrative control to cloud users.

These abstraction layers can also be thought of as a layered architecture, where services from one layer can be combined with services from another layer. For example, SaaS can provide the infrastructure to create services from higher layers. Let’s take a look at the layers of the cloud computing reference model.

1. SaaS

Software as a service (SaaS) is a form of application delivery that relieves users of the burden of software maintenance and makes development and testing easier for service providers.

The top layer of the cloud delivery model is where the application is deployed. End customers can access the services provided by this level through a web portal. Because online software services provide the same functionality as locally installed computer programs, consumers (users) are increasingly turning away from them. ILMS and other application software are now accessible via the web as a service.

SaaS is definitely a vital service in terms of data access, collaboration, editing, storage and document sharing. Email services in web browsers are the most well-known and widely used example of SaaS, but SaaS applications are becoming more collaborative and sophisticated.

The features of SaaS are as follows: 

• Cloud customers have full control over all cloud services.
• Providers have complete control over software-application-based services.
• Cloud providers partially control the implementation of cloud services.
• Consumers have no control over the implementation of these cloud services.

2. PaaS

Platform as a Service (PaaS) is a strategy that provides an infrastructure-oriented cloud that provides basic computing and storage capabilities (PaaS), as well as a high level of abstraction that makes the cloud easier to program. . Developers can create and deploy apps on cloud platforms without knowing how many processors or how much memory their applications will use. An example of a PaaS product that provides a scalable environment for building and hosting web applications is Google App Engine.

The characteristics of the PaaS layer are as follows:

• Cloud providers have complete authority or control over the provision of cloud services to consumers.
• Cloud customers can selectively control resources on application servers, databases, or middleware based on needed or selected resources.
• Consumers get an environment in which they can develop applications and databases. These environments are usually highly visual and very easy to use.
• Provides scalability and security options for your resources.
• Workflow and website building services.
• Services that connect your cloud platform to other external platforms.

3. IaaS

Infrastructure as a service (IaaS) provides storage and computing resources that developers and IT organizations use to deliver custom/business solutions. IaaS provides computer hardware (servers, networking technology, storage, and data center space) as a service. It may also include providing an OS and virtualization technology to manage resources. More importantly, IaaS customers rent computing resources rather than purchasing them and installing them in a data center. service is generally

Payment are made on a usage basis. This service may include dynamic scaling so that if a customer needs more resources than anticipated, they are readily available.

IaaS layer controls include:

• Consumers have full or partial control over their cloud, server, and database infrastructure.
• Consumers have control over virtual machine implementation and maintenance.
• Consumers can choose VM machines with a pre-installed operating system.
• The cloud provider has complete control over the data center and other hardware associated with it.
• Ability to scale resources based on user usage.
• You can also copy your data around the world, so you can access it as quickly as possible from anywhere in the world.

Types of Cloud Computing Reference Model

A variety of cloud computing reference models are used, depending on the different needs of consumers. The most important type of cloud computing reference models in cloud computing is the cloud reference model. The National Institute of Standards and Technology (NIST) is an organization designed by the United States Government (USG) to adopt and develop cloud computing standards.  

The principle of NIST Cloud computing reference architecture are: 

1. Create a vendor-neutral architecture that complies with NIST standards.
2. Establish the necessary technology solutions and create solutions that do not stifle innovation.
3. The NIST Cloud Computing Reference Architecture provides features such as elasticity, self-service, and resource collaboration.

The service models involved in this architecture are: 

1. Software as a Service (SaaS) 
2. Platform as a Service (PaaS) 
3. Infrastructure as a Service (IaaS) 

NIST Cloud computing also has 4 deployment models, which are as follows: 

1. Public

It is a model in which cloud infrastructure and resources are made available to the public over a public network. These models are usually owned by companies selling cloud services.

2. Private

It is a model where only cloud consumers have access to cloud infrastructure and resources. These models are typically owned by the cloud customer themselves or by a third party.

3. Community

It is a model where a group of cloud consumers share cloud infrastructure and resources because they have similar goals and policies to accomplish. These models are owned by your organization or a third party.

4. Hybrid

This model includes a mix of different deployment models, such as public, private and community. It helps in exchanging data and applications between different models.

The NIST Cloud Reference Model

Different cloud computing reference models are used to reflect different consumer needs. The National Institute of Standards and Technology (NIST) is an American organization responsible for the adoption and development of cloud computing standards. The NIST cloud computing model includes five key features:

• Measured Service
• On-demand self-service
• Resource pooling
• Rapid elasticity
• Broad network access

They follow the same three service models defined earlier: SaaS, PaaS and IaaS, and mention four deployment models: i.e., Private, Community, Public, and Hybrid cloud. 

The CSA Cloud Computing Reference Models

• Cloud security is a growing concern. With so much data available and distributed in the cloud, vendors must establish appropriate controls and limits. The Cloud Security Alliance (CSA) reference model defines these responsibilities. It states that IaaS is the most basic service tier, followed by PaaS and SaaS. Each has inherited the security complexities of its predecessor, which also means that any concerns spread even further. CSA suggests that any cloud computing model should include the following security mechanisms:
• Access control
• Audit trail
• Certification
• Authority

The OCCI Cloud Computing Reference Models

The Open Cloud Computing Interface (OCCI) is a set of specifications and standards that define how different cloud vendors provide services to their customers. This helps streamline the creation of system calls and APIs for all providers. This model not only helps in security but also in creating managed services, monitoring and other useful system administration functions. The main pillars of the OCCI Cloud Computing Reference Model are:

• Interoperability: This allows different cloud providers to work together without data conversion between multiple API calls.
• Portability: Increase competition in the market by breaking away from vendor lock-in and allowing customers to move between providers based on their business goals with limited technology costs.
• Integration: This functionality can be delivered to customers using any infrastructure.
• Extensibility: Metamodel and discovery capabilities allow OCCI servers to interact with other OCCI servers using extensions.

The CIMI & DMTF Cloud Computing Reference Models

The Cloud Infrastructure Management Interface (CIMI) model is an open standard specification of APIs for managing cloud infrastructure. CIMI’s goal is to help users manage cloud infrastructure by standardizing the interactions between cloud environments and developers. The CIMI standard is defined by the Distributed Management Task Force (DMTF). They provide the protocols used for the Representational State Transfer (REST) protocol using HTTP, but can also be extended to other protocols.

Each resource in the model has a MIME type that contextualizes the request and response payloads. URI identifies a resource. Each resource representation includes an ID attribute known as a “cloud entry point”. Links to this resource will be replicated in all other resources in the environment.

Examples of Cloud Computing Reference Models Apart From NIST

1. IBM Architecture 
2. Oracle Architecture 
3. HP Architecture 
4. Cisco Reference Architecture 

Major Actors in Cloud Computing Reference Models

There are five major actors in NIST cloud computing reference architecture. They are: 

1. Cloud Consumer 
2. Cloud Provider  
3. Cloud Carrier 
4. Cloud Auditor 
5. Cloud Broker

The below image will explain cloud computing reference model with a neat diagram.

Each actor is an entity that participates in the cloud computing process or performs a cloud computing duty. This entity can be an individual or an organization.

1. Cloud Consumer

The end users that cloud computing services are designed to support are cloud consumers. An individual or legal entity that works with a cloud provider and uses its services is called a cloud consumer. Cloud customers consume services by reading cloud providers’ service catalogs, making appropriate service requests, and entering into service contracts with cloud providers. Cloud customers may be charged for the services provided and must make payment arrangements. A cloud service agreement (SLA) is required. 

2. Cloud Provider

A cloud provider is an individual, group, or other entity that is responsible for making services accessible to cloud users. The cloud provider creates the requested software, platform, and infrastructure services, manages the technical infrastructure required to provide the service, provides the service at agreed service levels, and protects the security and privacy of the service.

Through service interfaces and virtual network interfaces that help abstract resources, cloud providers implement cloud software and make computing resources accessible to cloud consumers who use their infrastructure as a service.

3. Cloud Carrier

Cloud carriers act as intermediaries between cloud providers and customers, facilitating the connection and transfer of cloud services. Customers can access the cloud through networks, communications, and other access devices provided by the cloud provider. For example, cloud service customers can consume cloud services through network access devices such as laptops, mobile phones, PCs, and mobile Internet devices (MIDs). While networks and carriers are typically responsible for delivering cloud services, transport agents are companies that arrange for the physical delivery of storage devices such as high-capacity hard drives.

Note that cloud providers establish service level agreements (SLAs) with cloud carriers to provide services at a level consistent with the SLAs offered to cloud consumers. Cloud providers may also require cloud carriers to provide a dedicated encrypted connection between cloud consumers and cloud providers.

4. Cloud Auditor

Cloud auditors can provide an unbiased assessment of cloud services, information systems operations, performance, and security of cloud computing implementations. Cloud auditors may evaluate cloud provider services in terms of performance, compliance with service level agreements, privacy impact, and security controls.

The administrative, operational and technical precautions or measures used within an organization’s information system to ensure the confidentiality, availability and integrity of the system and its data are known as security controls.

To perform a security audit, a cloud auditor evaluates an information system’s security controls to determine how well they are implemented, function as intended, and achieve the desired results in relation to the system’s security requirements. Receive. Confirming compliance with laws and security policies should be part of a security audit.

5. Cloud Broker

Organizations called “cloud brokers” manage how cloud services are used, operated, and delivered and negotiate contracts between cloud providers and cloud users. As cloud computing evolves, it may become more difficult for cloud consumers to integrate cloud services. In some situations, a cloud consumer may request cloud services through a cloud broker rather than contacting the cloud provider directly. A single point of access to control multiple cloud services is provided by a cloud broker. The ability to provide a single, consistent interface to many different providers, whether the interface is for commercial or technical purposes, distinguishes cloud brokers from cloud service providers. Cloud brokers provide three types of services:

Intermediation 

Cloud brokers improve specific services by enhancing specific capabilities and providing value-added services to cloud customers. This enhancement can take the form of identity management, performance reporting, security improvements, and more. 

Aggregation 

A cloud broker connects multiple services and integrates them into one or more new services. Brokers provide data and service integration, ensuring secure data transfer between cloud customers and different cloud providers and providing these services.

Arbitrage 

Similar to service aggregation, service intermediation differs in that the services being integrated or aggregated are not fixed. Service arbitrage refers to the freedom of brokers to choose services from different service providers.

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