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Cloud Concepts – AWS Cloud Practitioner

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What is Cloud Computing

Cloud Computing–

  • Make use of the internet
  • Maintain data and application in remote servers to be accessed by users across the globe.

Hence, it uses the computer resources that are delivered as a service over the internet.

Figure 1: A basic structure of cloud computing

Evolution of cloud and types

Figure 2: How cloud computing evolved

Stages of evolution of cloud computing

  • PC Application Era – Since 1960s till the last of 20th century. Computing as utility developed with advancement as grid computing.
  • No Cloud Era – Since end of 20th century. Internet is used to provide Application/Software as Service.
  • Cloud Computation Era – The present era. “Cloud” refers to internet based access to computing, storage and data.

Figure 3: Generation of Cloud

Cloud Characteristics

Cloud computing features, by the National Institute of Standards and Terminology (NIST) are

  • Cost Efficiency: No need to deploy capital to purchase physical equipments and maintain them.
  • On-demand self-service: Provisioning of computing resources is automatic, as per user’s need, without human interaction.
  • Broad network access: Available over network, can be accessed anywhere, anytime and on any device (mobile phones, laptops, and PDAs).
  • Resource pooling: Multiple consumers are served using a multi-tenant model by pooling computing resources.
  • Device and location freedom – It can be accessed by a web browser regardless of location or device in use.
  • Rapid elasticity: Capabilities are elastically provisioned, to quickly scale out or scale in. Unlimited capabilities often appear to customer.
  • Measured service: Exhaustive metering capability for each type of service (e.g., storage, processing, bandwidth, etc). Resource usage can be managed, controlled, and reported transparently to the provider and consumer of the service.
  • Cloud computing systems typically use REST-based (Representational State Transfer) APIs (Application programming interface), to enable machines to interact with cloud software

Cloud Service Models

Figure 4: Models of cloud

Various cloud service models are

  • Infrastructure as a Service (IaaS)
  • Platform as a Service (PaaS)
  • Software as a Service (SaaS)

Infrastructure as a Service (IaaS) –

  • User accesses the physical hardware and can select as per need – CPU/storage/ etc.
  • Resource availability is managed by IaaS cloud providers.
  • Examples: Amazon CloudFormation, Rackspace Cloud, Google Compute Engine.
  • User installs operating system images with required application software.
  • Software patching and maintenance is responsibility of the user.
  • Virtual machines (VMs) run as guests by a hypervisor, like Xen or KVM with operating system, middleware, network, storage, data and applications.
  • IaaS payment depends upon resources subscribed, time used (per hour), usage of bandwidth (in gigabyte), storage(in gigabyte) or combination of any.

Figure 5: IaaS model

Platform as a Service (PaaS) –

  • Complete development platforms with development tool is provided
  • Developer builds applications without installing any tools on their computer and then deploy those applications without any specialized systems administration skills.
  • The computer and storage resources scale automatically to match application demand in PaaS.

Examples of PaaS include

  • App Engine  from Google: based on Python and Django
  • Force.com from SalesForce: based on the SalesForce SaaS infrastructure and Apex language

Figure 6: PaaS model

Software as a Service –

  • Application software hosted in cloud, catering to user’s need is provided on subscription basis
  • Application is accessed via web browser by users.
  • Various business applications are provided – collaboration, CRM, ERP, invoicing, HRM, etc
  • Reduces IT costs as less hardware and software maintenance costs.
  • SaaS applications provide application customization.
  • Users not responsible for hardware or software updates
  • Example – Google Apps, Dropbox, Salesforce

Figure 7: SaaS model

Cloud Types

Various cloud type offerings depending upon level of control, are

The Private Cloud – Complete private control similar to personal data centre setup. It offers private infrastructure as service. Also called “internal cloud computing”. Example – VMware vCloud and Citrix VDI.

The Public Cloud  – No control by user. Vendors offer cloud computing services like – Salesforce.com and ADP

The Hybrid Cloud – Itcombines both. Most company evolved from a traditional, private hardware infrastructure to a cloud-based one. For example, Cisco, offers IronPort Email Security as their hybrid solution and Google, known for hosted solution, offers Postini email archiving.

Link for free practice test – https://www.testpreptraining.com/aws-certified-cloud-practitioner-free-practice-test

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