Saturday 6 September 2014

Difference between Cloud Computing and Distributed Computing

Cloud computing is a style of computing in which resources are made available over the internet. Most often, these resources are extensible and are highly visualized resources and they are provided as a service. These resources can mainly be broken down to applications, platforms or infrastructure.
The field of computer science that deals with distributed systems (systems made up of more than one self-directed nodes) is called distributed computing. Typically, distributed computing is used to utilize the power of multiple machines to achieve a single large scale goal.

What is Cloud Computing?

Cloud computing is the emerging technology of delivering many kinds of resources as services, mainly over the internet. Delivering party is referred to as the service providers, while the users are known as the subscribers. Subscribers pay subscription fees typically on a per-use basis. Cloud computing is broken down in to few different categories based on the type of service provided. SaaS (Software as a Service) is the category of cloud computing in which the main resources available as a service are software applications. PaaS (Platform as a Service) is the category/application of cloud computing in which the service providers deliver a computing platform or a solution stack to their subscribers over the internet. IaaS (Infrastructure as a Service) is the category of cloud computing in which the main resources available as a service are hardware infrastructure. DaaS (Desktop as a Service), which is an emerging –aaS service deals with providing a whole desktop experience over the internet. This is sometimes referred to as desktop virtualization/virtual desktop or hosted desktop.





Examples of Cloud Computing Services

These examples illustrate the different types of cloud computing services available today:
Amazon EC2 - virtual IT
Google App Engine - application hosting
Google Apps - software as a service
Apple MobileMe - network storage

Some providers offer cloud computing services for free while others require a paid subscription.

Cloud Computing Pros and Cons

Service providers are responsible for installing and maintaining core technology within the cloud. Some customers prefer this model because it limits their own manageability burden. However, customers cannot directly control system stability in this model and are highly dependent on the provider instead.

Cloud computing systems are normally designed to closely track all system resources, which enables providers to charge customers according to the resources each consumes. Some customers will prefer this so-called metered billing approach to save money, while others will prefer a flat-rate subscription to ensure predictable monthly or yearly costs.

Using a cloud computing environment generally requires you to send data over the Internet and store it on a third-party system. The privacy and security risks associated with this model must be weighed against alternatives.


What is Distributed Computing?

The field of computer science that deals with distributed systems is called distributed computing. A distributed system is made up of more than one self-directed computers communicating through a network. These computers use their own local memory. All computers in the distributed system talk to each other to achieve a certain common goal. Alternatively, different users at each computer may have different individual needs and the distributed system will do the coordination of shared resources (or help communicate with other nodes) to achieve their individual tasks. Nodes communicate using message passing. Distributed computing can also be identified as using a distributed system to solve a single large problem by breaking it up to tasks, each of which is computed in individual computers of the distributed system. Typically, toleration mechanisms are in place to overcome individual computer failures. Structure (topology, delay and cardinality) of the system is not known in advance and it is dynamic. Individual computers do not have to know everything about the whole system or the complete input (for the problem to be solved).

Example : Hadoop, Google has it's own distributed system.





What is the difference between Cloud and Distributed Computing?

Cloud computing is a technology that delivers many kinds of resources as services, mainly over the internet, while distributed computing is the concept of using a distributed system consisting of many self-governed nodes to solve a very large problem (that is usually difficult to be solved by a single computer). Cloud computing is basically a sales and distribution model for various types of resources over the internet, while distributed computing can be identified as a type of computing, which uses a group of machines to work as a single unit to solve a large scale problem. Distributed computing achieves this by breaking the problem up to simpler tasks, and assigning these tasks to individual nodes.

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