Cloud Computing Logical Architecture

Published Date: 02 Nov 2017

Cloud computing is an internet based computing using shared resources available remotely. In this computing technique, the inner workings are hidden from the end users. This technique is new model for IT field and a product where applications are accessed via internet.

So far there is no exact definition for cloud computing, but it can be defined as: "cloud computing is a type of computing environment, where IT businesses outsource their computing needs which includes software application services to outside vendors and when they are in need of computing power or other resources like storage, database, emails etc., which are accessed via WWW."

Cloud Computing System can be divided into two parts, front end and back end. The interconnection between them is done via internet for making use of it. Front end side is used the customers and back end refers to service providers.

The front end contains customer’s device comprising of computer and a network. And also applications for accessing the back end system, i.e. cloud systems. Front end refers to the interface though which a customer can make use of the services rendered by the cloud computing system.

Back end contains physical devices or peripherals. It also contains various computer resources such as CPU and data storage systems. Group of these resources is termed as cloud computing system. A dedicated server is used for administration purpose. It monitors the consumer’s demands, traffics etc.

A provider who provides some kind of service may have many consumers requiring large storage space. Cloud computing system requires minimum twice the units of storage devices, as the system keeps all the information of its clients. Clouding computing is no more an new technology and because of its various capabilities it has gained popularity amoung small and medium sized business peoples. When using cloud computing, all the consumer’s data are not stored in his place, it is stored in service providers storage area. When the consumer needs any data, he can retrieve it via internet.

2.1.2 Example of cloud computing

A good example is Gmail and Yahoo both use cloud computing technology. When users send or receive email, he never uses any application software available in his computer. He just use an internet connection to send mails. The operating cost of the cloud computing is comparatively low when considering personal infrastructure. The only concern in the cloud computing technology is security and privacy.

2.1.3 Cloud computing Types

Cloud computing environment can be broadly classified based on infrastructure they are i) public cloud, ii) private cloud and iii) hybrid cloud.

Public cloud: It is off-premises or external one. Public cloud is widely used model where infrastructure comprising of hardware systems, network, storage and applications are provided and owned by the provider. When the organization needs some kind of security for their applications, data then they jump to private cloud, which is behind the firewall and accessed only by customers belonging to that organization.

Private cloud: It is an on-premises or internal cloud setup.

Hybrid cloud: It is combination of both public and private clouds.

2.1.4 Why we need cloud computing?

The main usage of cloud computing is a consumers need not to pay for the infrastructure and its cost for maintenance. As a consumer he/she has to pay the service charges according to his/her usage of various resources. Moreover, consumers need not to worry about updating software, backups and anti-virus.

2.1.5 Problems with Cloud Computing

Cloud computing is cost effective for IT organizations in-terms of maintenance and operation. But the major concerns are security and privacy. Besides these concerns in cloud computing, when comparing with other existing computing solutions, scope of becoming a matured computing system is more because of its cost effectiveness and reliability. As the data are outsourced and resides in vendors premise, a doubt of trust worthiness remains always.

Banking and Governmental data are most sensitive. When there a leak in consumer’s information for eg., credit card details, then it creates more problems for the agency and also for the consumer. Cloud computing will be opted by the business persons when there exists a strict rules and standards for its operation.

2.1.6 Cloud Computing Service Architecture

Google Apps is a computation service known as Google’s business solution. Other big names in cloud computing services are: Microsoft, IBM, Amazon, HP and DELL.

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Fig 6: Cloud Computing Stack

Mainly, three types of services are available from a cloud service provider (figure 6).

Infrastructure as a service: provider takes care of the cost for the resources such as servers, equipments for networking, backups and storage.

Platform as a service: provider only provides the platform or solutions for the consumers.

Software as a service: provider will give consumers to use the software applications available in their premises.

2.1.7 Understanding cloud computing architecture models

The biggest problem in cloud computing is there no defined standard or architecture. Cloud architectures can be viewed as a collection of different functionalities and capabilities. A cloud computing system has various IT resources deployed in remote placed and designed to run applications dynamically.

Cloud computing models

Potential of cloud computing is exciting and limitless in-terms of applications.

 Simplest cloud computing model can be viewed a collection of servers which are virtualized using a tool. This model appears to be a single pool having many servers. Problems persist in these types of models where serves are dedicated to a particular set of applications.

Cloud architectures use a tool that deploys the cloud supported applications. An example is PaaS model is used Salesforce.com.

Another model can be built for network providers who need storage and server technology. The providers will provide these resources and consumes will create an image or instance and make use of it. The original server and storage will be residing in provider’s premises.

The full version of cloud computing model use virtualization technology for making the resources virtual. The resources such as network, storage, computing power etc., are virtualized. Examples are IBM/Google cloud computing model and using this model Cisco is developed.

2.2 Developing Holistic Cloud Computing Reference Model

The "cloud" in cloud computing refers a set of hardware, storage, networks, services and interfaces that are combined to deliver as a service.

Consumer Cloud computing services are widely used in internet. Examples are mail and social networking sites. Usage of Cloud Computing by the IT organizations sector is low, because of concerns such as security risks, challenges in terms of privacy and data.

For adopting the cloud services, factors in cloud computing services should be documented and informed to consumers. The documents should cover Governance, Compliance and Risk factors.

Data are stored across borders. Each country may have different cyber law and this has to be taken in account while transferring data across border.

2.2.1 Cloud Computing: Taking an Complete View

It's not a technology play in fact it may be hard to identify a single piece of new technology that is fundamental to cloud. Cloud computing makes much more efficient use of resources. In old days resources are essentially used for processing power and storage but increasingly the focus of cloud converged on efficient use of software resources.  The concept of a user being able to gain access to and pay for these resources on a per-use basis makes great economic sense.

Over the next ten years we will use this technology until any flaw is found. What makes cloud so interesting is that every one of the global vertical industries have two conversations about the cloud, first one how do we become a cloud user to enable more efficient operations and second one, how do we leverage our existing platform assets to become a cloud provider.

2.2.2 Complete view of cloud management

Cloud computing has not yet reached its full potential. Obstacles for cloud adoption are confusion among different deliver models and deployment methods. Other concerns relate to risk of outsourcing, data legislation issues, inability to assess service providers etc. In addition to these obstacles to cloud computing as a concept, there are also technological thresholds in today's cloud offerings, making service provisioning a tedious process.

The five top level research area for analyzing obstacles in cloud computing are:

Optimization in deployment, construction of cloud services.

Self-preservation in resource management.

Self management for various cloud services and decision making.

Support for service deployment.

Market and legislative issues.

2.2.3 Cloud Computing Reference Model

The Cloud computing Reference Model (CC-RM) is facilitates the process of modeling the cloud, architecture and planning the deployment activities. It also establish a foundation for modeling the cloud and its architecture, from which an IT organization can plan, architect, model and deploy, to address business and technical challenges. Cloud is not a problem solving architecture, it is a collection of services, which can be used to solve the problem.

The Cloud reference model consists of four elements / models, shown below:

Cloud Enablement Model

This model describes the various layers of cloud and its enablement for business operations. This model comprises various cloud computing technologies and solutions for the consumers given by the providers.

Cloud Deployment Model

The cloud deployment model (CDM) describes different varieties of Cloud deployment models available to the various cloud models such as private, public, hybrid and community clouds.

Cloud Governance and Operations Model

Defines the requirements for cloud computing, such as governance, privacy, security operations, management, support and monitoring.

Cloud Ecosystem Model

The Cloud Ecosystem takes cares of developing and sustaining. It consists of Cloud providers, consumers, intermediaries and network.

The Cloud Computing Reference Model has four sub-models, they are:

Cloud Virtualization Tier

Focuses on the range of technologies and tools that provide hardware and infrastructure virtualization, computing, storage, network and security virtualization.

Cloud Operating System Tier

Focuses on the Cloud technologies that enable virtualization of resources as Cloud enabled capabilities. Cloud OS tier provides provisioning, billing and metering, load balancing, resource management, monitoring and management, workflow and orchestration of Cloud-enabled resources.

Cloud Platform Tier

Contains technologies and tools, which enable platforms to be assembled and delivered as a service (PaaS), and includes SOA and Web services.

Cloud Business Tier

Contains various range of business capabilities and business solutions that are designed and provisioned to consumers as services via the Cloud.

Cloud Deployment Model (CDM)

The CDM provides an explicit framework for identifying the requirements and differences of various Cloud deployment scenarios.

The Cloud deployment model and the Cloud Enablement Model are key decisions that determine in many aspects like security, architectural and management challenges. The various Cloud deployment model scenarios are i) Private Internal Cloud, ii) Public External Cloud, iii) Hybrid Integrated Cloud and iv) Community Cloud.

The Cloud Deployment Model and the Cloud Enablement Model are central requirements of the Cloud computing Reference Model.

Cloud Governance and Operations Model

The Cloud Governance and Operations Model helps in making choices regarding Cloud Enablement approaches in terms of Cloud deployment model. The primary elements of the Cloud Governance and Operations Model are i) Cloud Governance, ii)Security and Privacy, iii)Management and Monitoring and iv)Operations and Support.

Cloud Ecosystem Model

The last model in CC-RM is the Cloud Ecosystem Model. The Cloud Ecosystem is the physical, logical and virtual environment in which Cloud providers, consumers, solution and technology providers help cloud computing to drive smooth and legitimate business and technology trend. The key elements of the Cloud Ecosystem Model are i) Cloud Network/Dial Tone, ii) Cloud Ecosystem Enablement, and iii) Cloud Consumers and Cloud Providers.

2.3 Cloud’s System Architecture

Figures shown below are the examples of cloud-based solution architecture. Architecture stated below can be deployed using existing templates available in MultiCloud Marketplace.   

Things to Consider

Factors to be considered while designing cloud based architectures are highlighted below:

Cost: Clearly understand the pricing models for various cloud models.

Complexity: Analyze the complexity before customizing the cloud solution and properly check the requirements before deployment.

Speed: Check the speed for cloud model. Speed in-terms of advanced CPU architecture, high memory, lowest latency and network infrastructure. 

Cloud Portability: Check portability. This allows the consumer to move from one vendor to another without making much change in the architecture.  

Security: Check for the security measurements provided by the vendor. 

2.3.1 Example Reference Diagrams

The architecture diagrams below shows a progress from simple to complex reference architectures. 

Single Cloud Site Architectures

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Fig 7: Single Cloud Site Architecture

 Figure 7 shows that in the single cloud site architecture, load balancer, application logic, databases and storage are located in the cloud, i.e. Load Balancing Server, Application Server, Database Server. If the user is only testing the interactivity between tiers, he may use non-redundant system architecture to save costs and resources. As shown in figure 7, dedicated servers are there for each tier of the application which form a non redundant architecture. For production environments this kind of architecture is not recommended.

Redundant 3-Tier Architecture

In the figure 8 shown below, two servers in load balancer, application and database are available.  A redundant architecture will help protect the site/application from system downtime. 

Figure 8 demonstrates that the use of a striped volume set at the database tier. If the database is large and requires faster backups, we have to consider using a set of striped volumes for data storage.  

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Fig 8: Redundant 3-Tier Architecture

Multi-Datacenter Architecture

If the cloud infrastructure has many datacenters, it's recommended to distribute system architecture in different multiple datacenters for redundancy and protection.  

Figure 9 shows the multiple datacenters in reference architecture. It shows the multi datacenter architecture, in which it has two data centers, each having a load balancing, application, volume and master database. When on datacenters goes down, then automatically datacenter 2 can be used.

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Fig 9: Multi-Datacenter Architecture

2.4 Cloud Deployment Model

2.4.1 Cloud Computing Deployment Models

NIST has standardized the characteristics of cloud computing as ubiquitous network access, on-demand self-service, elasticity, resource pooling, and pay on use.

Private Cloud

Private cloud infrastructure is dedicated to a single particular organization or group. It is not shared with other organizations. Private cloud can be owned or leased. It can be managed by the IT organization or a vendor who provided the service and can exist at on-premises or off-premises. Private cloud is more expensive and secure when compared to public cloud. Private clouds are flexible and service-based. Private cloud is hosted inside the organization’s firewall. It can be accessed by users within the organization via intranet as shown in figure 11.

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Fig 11: Private cloud

Public Cloud

Public cloud provides an elastic, cost-effective way to deploy IT solutions. The term public doesn’t mean that users’ data is publicly visible. Public cloud infrastructure is offered via web applications and also as web services over the internet to the public as shown in figure 12. Public cloud involves applications such as customer relationship management (CRM), messaging and office productivity. Public cloud providers such as Google or Amazon offer an access control to their clients.

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Fig 12 Public cloud

Hybrid Cloud

This cloud deployment model exists due to mixed needs of an organization. It is combination of two or more cloud service deployment models (Private, Public and Community) as shown in figure 13. Organizations may host critical applications on private cloud and applications with relatively less security concerns on the public cloud.

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Fig. 13 Hybrid cloud

A combination of a public and a private cloud is joined together for the purpose of keeping business-critical data and services in their control on private cloud and outsourcing less-critical processing to the public cloud.

Community Cloud

Community cloud is a infrastructure shared by several IT organizations and supports to a specific community that have common concerns like security requirements, mission, compliance considerations and policy.

Combined Cloud

Combined cloud is formed when two clouds are joined together. It consists of multiple internal and external providers. By integrating multiple cloud services, consumers can ease the transition to public cloud services.

Inter Cloud (Cloud of Clouds)

Mesh of cloud is called as Inter cloud which is interconnected using open standards to provide a universal acceptance.

2.4.2 Types of Cloud Deployment Models

There are three types of cloud deployment models available however there are is one another type of cloud deployment model known as community cloud which is being used in some instances. Table 1 list the various cloud deployment models and highlights its characteristics.

Table 1: Cloud Deployment Models

Public Cloud

•Provider Owned &

Managed

•Access by Subscription

•Economic Benefits:

•Reduced IT Service

Delivery cost

• Reduced HW, Systems, software, management and application costs.

Private Cloud

•Client Dedicated

•Access defined by client

•Data Governance rules/regulations

•More Secure

•Economic Benefits:

•Reduced Capex

•Reduced Opex

•Service Level Discipline

Hybrid Cloud

•Enterprise Computing and

private cloud extend outward to consume public compute resource

for peak needs

•Economic Benefits

•Scale private cloud for BAU

•Maintain service levels by scaling externally

•Share cost with vertical with charge back options

Key Patterns:

•User initiated consumption of compute/storage resources through service catalogue self service portal

•Highly scalable and automated provisioning of commodity compute resource

•Pay per use metering & billing

Key Patterns:

•Resource driven

provisioning of

development, test and

production systems

Managing E2E Lifecycle

•Provisioning systems

quickly and application on

boarding with minimal

human effort

Key Patterns:

•Policy driven acquisition of external compute resources beyond the data center firewall

•Shift commodity workloads at periods of peak usage consumption to external compute/storage resources