Cloud Computing Overview

Cloud Computing Overview

Cloud computing is a general term for the delivery of hosted services over the internet.

Cloud computing enables companies to consume a compute resource, such as a virtual machine (VMs), storage or an application, as a utility -- just like electricity -- rather than having to build and maintain computing infrastructures in house.

Example:

Office 365 which allows users to store, access, edit their Ms-office documents online (Browser)
without installing the actual program on their device.

The architecture of cloud computing comprises of the following components −

• Front-end device
• Back-end platform
• Cloud-based delivery
• Network

Types of Clouds

• Public

           These are open to public and their infrastructure is owned and operated by service providers as            in case of Google and Microsoft.

• Private 

          These clouds are dedicated to a particular organization. That particular organization can use the           cloud for storing the company's data, hosting business application, etc.

• Hybird 

        Organizations can use private clouds for sensitive application, while public clouds for non-                 sensitive applications. The hybrid clouds provide flexible, scalable and cost-effective solutions           to the organizations.

Benefits of Cloud

• Cloud service offers scalability. Allocation and de-allocation of resources is dynamically as per demand.
• It saves on cost by reducing capital infrastructure.
• It allows the user to access the application independent of their location and hardware configuration.
• It simplifies the network and lets the client access the application without buying license for individual machine.
• Storing data on clouds is more reliable as it is not lost easily

Cloud Models

• SaaS is Software as a service

• PaaS is Platform as a service

• IaaS is Infrastructure as a Service

SaaS

Software as a Service (SaaS) provides a complete software solution which you purchase on a pay-as-you-go basis from a cloud service provider. You rent the use of an app for your organisation and your users connect to it over the Internet, usually with a web browser. All of the underlying infrastructure, middle ware, app software and app data are located in the service provider’s data center. The service provider manages the hardware and software and with the appropriate service agreement, will ensure the availability and the security of the app and your data as well. SaaS allows your organisation to get quickly up and running with an app at minimal upfront cost.

Advantages of SaaS

• The most cost effective Cloud service as you only lease the software and not the resource.

• SaaS requires minimal planning and is easy to setup, as applications are usually simple in usage and readymade.

• Rapid deployment as the software is fully provisioned on demand.

• The customer does not need to worry about the management of applications, as this is all handled by the provider.

• Software is usually very stable, as it is supported by the Cloud provider’s large infrastructure and I.T team.

Disadvantages of SaaS

• The customer has no control over the system processing its data.

• There is no control over which customers use the software; the software is used by a large amount of users. An example of SaaS would be Dropbox.

• Little or no control over the parameters of software.

• Little control over deployment, upgrade and testing methodology (e.g. Dev, UAT, Live systems availability)

• Currently only a limited number of software solutions are offered in the form of SaaS.

• Integration with other software on any other systems is either difficult or unsupported (e.g. single sign-on)

• Cloud provider has full access to customers’ data, unless cryptography is used (But this would mean no processing could be done on the Cloud thus reducing the usefulness of the Cloud).

PaaS

Platform as a service (PaaS) is a category of cloud computing services that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app. PaaS can be delivered in two ways: as a public cloud service from a provider, where the consumer controls software deployment with minimal configuration options, and the provider provides the networks, servers, storage, operating system (OS), 'middleware' (e.g. Java runtime, .NET runtime, integration, etc.), database and other services to host the consumer's application; or as a private service (software or appliance) inside the firewall, or as software deployed on a public infrastructure as a service

Advantages of PaaS

• Still cost effective in comparison to IaaS, as you are still essentially leasing the software platform not a resource. An example of PaaS would be IIS.
• Unlike SaaS you can bring your own software to run on the platform therefore you have full control of software.

• Full control over the users accessing the software and the processing of data (to a certain extent, due to little knowledge of underlying VM and insider threat).

• Improved support for integration with other systems due to the above.

• Minimal management of the VM, as this is still handled by the provider.

Disadvantages of PaaS

• No Control over the VM or processing of data, this is a big security risk as you don’t know what’s happening with your data.

• Possibly no control over platform depending on Cloud provider.

• Platform is most likely a shared platform, for example there could be other customers running different websites on the same IIS platform.

• Management task can become time consuming and tedious as you are responsible for updates and upgrades of application.

• Not as cost effective as SaaS and not as much control over VM as IaaS.

Iaas

Infrastructure as a service (IaaS) is a managed compute service that gives complete control of the operating systems and the application platform stack to the application developers. It lets the user to access, manage and monitor the data centers by themselves.

Advantages of IaaS

• Customers have full control over their VM and everything inside it; customers can choose to automate the provisioning or build their own VM.

• A customer can run anything they want inside their VM.

• Full control of processing inside VM.

• Simplifies Integration with enterprise infrastructure

• Potential the most secure Cloud service using a PuC due to greater control of VM.

• The customer in essence can run and control its own virtual infrastructure without the overheads of cost and maintenance from running its own hardware.

Disadvantages of IaaS

• Most expensive, since the customer is now leasing a tangible resource, the provider can charge for every Cycle, bit of RAM or disk space used.

• Customer responsible for backups

• Unlike with SaaS or PaaS, customer is responsible for all aspects of VM Management.

• Still no control over which server or the physical (geographical) location of the VM.

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