Cloud Computing has 3 layers: Software and Application services Operating System on which to build Platform and run your applications. Physical Hardware on which to run Infrastructure the Operating System.... and all 3 can be delivered and managed over the internet as a service.
Software as Service (SaaS)• Software delivery model in which software and its associated data are hosted centrally (typically in the Internet cloud).• No need to pay license, subscription model (pay as you go like utility bill). SaaS Provider Thin “Cloud Clients”
Software as Service (SaaS) • Key target audience: End Users (both companies and consumers). • Examples: SaaS Customer Relationship Management (CRM) provider. Google Apps: SaaS provider of email, calendar and office documents (spreadsheet, word processing, etc)Online Exchange Server (email), Sharepoint (documentcollaboration and sharing and Office Web Apps.
Platform as Service (Paas)• Provides both a computing platform and a solution stack as a service. Build Host Scale Build the Host it in the PaaS Cloud OS systems application the in provider’s are able to PaaS provider’s OS computing dynamically scale platform. hardware. according to demand.
Platform as Service (Paas) • Key target audience: Developers (“come run your code on our platform”) and Companies (“port your applications to our platform”). • Examples:One of the pioneers in PaaS, originally built onRuby. First to implement “polyglot” (support for Google Cloud Engine: Allowsseveral programming languages). Popular use of Python, Java, PHP, JRuby andNoSQL. others. Uses GQL instead of SQL (google specialized database system). Wide availability of APIS .MS Solution, able to run .NET, Java, PHP andothers. Worldwide CDN across 24 datacenters.
Infrastructure as a Service (Saas)• Made possible by Virtualization: Computers are able “emulate” others. Think of a “a dream inside a dream”, or translating from one language to another in your head, or running SNES games on your pc. The PC “emulates” the SNES hardware.
Infrastructure as a Service (Saas)• Well… if you can run one Nintendo inside your pc… You can probably run two if you have a powerful enough computer….
Infrastructure as a Service (Saas)• …. Or several with a powerful server. • The necessary requirement is only that we “package” these virtual computers so that they are able to run independently and concurrently on the same hardware. Virtual computers are packaged into virtual “image files”.
Infrastructure as a Service (Saas)• Cloud providers offer computers – as physical or more often as virtual machines, as an on demand service from large pools of hardware resources in their data center.• Cloud users then install operating system images on the machines as well as their application software Linux Mail Oracle Server Database Server Windows Sharepoint Server
Infrastructure as a Service (Saas)• Key target audience: IT Departments (“don’t buy and own your own hardware infrastructure instead rent it from us on a per use basis”)• Examples:Virtual Infrastructure management Amazon EC2 allows users to renttool. Used by Rackspace and Nasa. virtual computers on which to runAllows companies to provide cloud their own computer applications. Thecomputing services using commodity underlying infrastructure uses the Xenhardware. Virtual Hypervisor.
Barriers to Adoption of the Cloud• Education and expertise (to move beyond the marketing abuse of the word cloud).• Data security concerns (results in “private clouds”).• Governance (lack of tools to easily manage scaling up and down).• Economies of scale (pooling of enough demand together to create momentum).• Danger of “lock in”, need ability to easily transfer from one provider to another.