Cloud Computing : Levels (IaaS, PaaS, SaaS)
Cloud computing relies on sharing of resources to achieve coherence and economies of scale, similar to a utility (like the electricity grid) over a network.
Cloud computing, or in simpler shorthand just “the cloud”, also focuses on maximizing the effectiveness of the shared resources. Cloud resources are usually not only shared by multiple users but are also dynamically reallocated per demand. This can work for allocating resources to users. For example, a cloud computer facility that serves European users during European business hours with a specific application (e.g., email) may reallocate the same resources to serve North American users during North America’s business hours with a different application (e.g., a web server). This approach should maximize the use of computing power thus reducing environmental damage as well since less power, air conditioning, rack space, etc. are required for a variety of functions. With cloud computing, multiple users can access a single server to retrieve and update their data without purchasing licenses for different applications.
In principle, cloud computing implementations offer seemingly infinite pooled computing resource over the network
– users can start, stop, and scale (up and down) its power at will
Comes close to the idea of utility computing:
– Ideally computing is provided the same way as e.g. water or electricity; available in every home and charged based on consumption, outsourcing all the hardware and getting charged by the use.
Levels of Cloud Computing:
B. Platform as a Service (PaaS)
– Offers a computing platform and/or software stack as a service
– Often consuming IaaS and sustaining SaaS cloud applications
C. Software as a Service (SaaS)
– While IaaS and PaaS are aimed for a software developer, SaaS is often aimed directly to the end user
– Accessible via a browser and/or API (SOA services)
A. Public Cloud: Low cost.. “Leased”.. Servers, (Near) Infinite Scale, Utility- based-pricing
B. Private Cloud: You own hardware.. in house, Limited scale, Fixed cost..Total control
C. Hybrid Cloud: Combination of two, Control where you need, scale when you need