What is Cloud Computing ? – Day 1

The practice of using a network of remote servers hosted on the Internet to store, manage, and process data, rather than a local server or a personal computer. Cloud computing is a computing term or metaphor that evolved in the late 2000s, based on utility and consumption of computer resources. Cloud computing involves deploying groups of remote servers and software networks that allow centralized data storage and online access to computer services or resources. Clouds can be classified as public, private or hybrid. by wikipedia

In cloud computing, the word cloud (also phrased as “the cloud”) is used as a metaphor for “the Internet,” so the phrase cloud computing means “a type of Internet-based computing,” where different services such as servers, storage and applications are delivered to an organization’s computers and devices through the Internet. If you google about cloud computing you will file thousand of website on that. Recently i was look for some information and i found howstuffworks.com, its really cool website and contains lots of good information on various things.  Their is good description given on how cloud computing works and most of the data in this post is belong from there. I have also get some data from  http://www.tutorialspoint.com/. I just put all the information on cloud computing together to give brief description on it.

How Cloud Works :

Let’s say you’re an executive at a large corporation. Your particular responsibilities include making sure that all of your employees have the right hardware and software they need to do their jobs. Buying computers for everyone isn’t enough — you also have to purchase software or software licenses to give employees the tools they require. Whenever you have a new hire, you have to buy more software or make sure your current software license allows another user. It’s so stressful that you find it difficult to go to sleep on your huge pile of money every night. Soon, there may be an alternative for executives like you. Instead of installing a suite of software for each computer, you’d only have to load one application. That application would allow workers to log into a Web-based service which hosts all the programs the user would need for his or her job. Remote machines owned by another company would run everything from e-mail to word processing to complex data analysis programs. It’s called cloud computing, and it could change the entire computer industry. In a cloud computing system, there’s a significant workload shift. Local computers no longer have to do all the heavy lifting when it comes to running applications. The network of computers that make up the cloud handles them instead. Hardware and software demands on the user’s side decrease. The only thing the user’s computer needs to be able to run is the cloud computing system’s interface software, which can be as simple as a Web browser, and the cloud’s network takes care of the rest.

Cloud Computing Architecture:

When talking about a cloud computing system, it’s helpful to divide it into two sections: the front end and the back end. They connect to each other through a network, usually the Internet. The front end is the side the computer user, or client, sees. The back end is the “cloud” section of the system. The front end includes the client’s computer (or computer network) and the application required to access the cloud computing system. Not all cloud computing systems have the same user interface. Services like Web-based e-mail programs leverage existing Web browsers like Internet Explorer or Firefox. Other systems have unique applications that provide network access to clients. On the back end of the system are the various computers, servers and data storage systems that create the “cloud” of computing services. In theory, a cloud computing system could include practically any computer program you can imagine, from data processing to video games. Usually, each application will have its own dedicated server.

The http://www.tutorialspoint.com/ contains very good description on cloud computing architecture.  The following information is belongs from their.




Front End refers to the client part of cloud computing system. It consists of interfaces and applications that are required to access the cloud computing platforms, e.g., Web Browser.


Back End refers to the cloud itself. It consists of all the resources required to provide cloud computing services. It comprises of huge data storage, virtual machines, security mechanism, services, deployment models, servers, etc.

Important Points

  • It is the responsibility of the back end to provide built-in security mechanism, traffic control and protocols.
  • The server employs certain protocols, known as middleware, helps the connected devices to communicate with each other.

Cloud Infrastructure Components

Cloud infrastructure consists of servers, storage, network, management software, and deployment software and platform virtualization.




Hypervisor is a firmware or low-level program that acts as a Virtual Machine Manager. It allows to share the single physical instance of cloud resources between several tenants.


Management Software helps to maintain and configure the infrastructure.


Deployment software helps to deploy and integrate the application on the cloud.


Network is the key component of cloud infrastructure. It allows to connect cloud services over the Internet. It is also possible to deliver network as a utility over the Internet, i.e., the consumer can customize the network route and protocol.


Server helps to compute the resource sharing and offer other services such as resource allocation and deallocation, monitoring resources, security, etc.


Cloud uses distributed file system for storage purpose. If one of the storage resource fails, then it can be extracted from another one which makes cloud computing more reliable.

  • Infrastructural Constraints

Fundamental constraints that cloud infrastructure should implement are shown in the following diagram:




Since virtualization is the key to share resources in cloud environment. But it is not possible to satisfy the demand with single resource or server. Therefore, there must be transparency in resources, load balancing and application, so that we can scale them on demand.


Scaling up an application delivery solution is not that easy as scaling up an application because it involves configuration overhead or even re-architecting the network. So, application delivery solution is need to be scalable which will require the virtual infrastructure such that resource can be provisioned and de-provisioned easily.


To achieve transparency and scalability, application solution delivery will need to be capable of intelligent monitoring.


The mega data center in the cloud should be securely architected. Also the control node, a entry point in mega data center also needs to be secure.

Public Cloud Model

The Public Cloud allows systems and services to be easily accessible to general public, e.g.,Google, Amazon, Microsoft offers cloud services via Internet.



There are many benefits of deploying cloud as public cloud model. The following diagram shows some of those benefits



Since public cloud share same resources with large number of consumer, it has low cost.


Since public cloud employs large number of resources from different locations, if any of the resource fail, public cloud can employ another one.


It is also very easy to integrate public cloud with private cloud, hence gives consumers a flexible approach.


Since, public cloud services are delivered through Internet, therefore ensures location independence.


Public cloud is also based on pay-per-use model and resources are accessible whenever consumer needs it.


Cloud resources are made available on demand from a pool of resources, i.e., they can be scaled up or down according the requirement.

Private Cloud Model

The Private Cloud allows systems and services to be accessible with in an organization. The Private Cloud is operated only within a single organization. However, It may be managed internally or by third-party.



There are many benefits of deploying cloud as private cloud model. The following diagram shows some of those benefits:



Private cloud operations are not available to general public and resources are shared from distinct pool of resources, therefore, ensures high security and privacy.


Private clouds have more control on its resources and hardware than public cloud because it is accessed only within an organization.


Private cloud resources are not as cost effective as public clouds but they offer more efficiency than public cloud.

  • Disadvantages

Here are the disadvantages of using private cloud model:


Private cloud is only accessible locally and is very difficult to deploy globally.


In order to fulfill demand, purchasing new hardware is very costly.


Private cloud can be scaled only within capacity of internal hosted resources.


In order to maintain cloud deployment, organization requires more skilled and expertise.

Hybrid Cloud Model

The Hybrid Cloud is a mixture of public and private cloud. Non-critical activities are performed using public cloud while the critical activities are performed using private cloud.



There are many benefits of deploying cloud as hybrid cloud model. The following diagram shows some of those benefits:



It offers both features of public cloud scalability and private cloud scalability.


It offers both secure resources and scalable public resources.


Public cloud are more cost effective than private, therefore hybrid cloud can have this saving.


Private cloud in hybrid cloud ensures higher degree of security.



Networking becomes complex due to presence of private and public cloud.


It is necessary to ensure that cloud services are compliant with organization’s security policies.


The hybrid cloud model is dependent on internal IT infrastructure, therefore it is necessary to ensure redundancy across data centers.

Community Cloud Model

The Community Cloud allows system and services to be accessible by group of organizations. It shares the infrastructure between several organizations from a specific community. It may be managed internally or by the third-party.



There are many benefits of deploying cloud as community cloud model. The following diagram shows some of those benefits:


Community cloud offers same advantage as that of private cloud at low cost.

  • Sharing Between Organizations

Community cloud provides an infrastructure to share cloud resources and capabilities among several organizations.


Community cloud is comparatively more secure than the public cloud.


  • Since all data is housed at one location, one must be careful in storing data in community cloud because it might be accessible by others.
  • It is also challenging to allocate responsibilities of governance, security and cost.

References :

  1. http://www.tutorialspoint.com/cloud_computing/
  2.  howstuffworks.com,

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