Part 3 : Approaches to Cloud Computing

There are various broad ways a cloud-based service is consumed and utilized. In the world of cloud computing, there are three different approaches, called service models, to cloud-based services : Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), and Software-as-a-Service (SaaS).
Let's discuss about each of them in detail.

Infrastructure as a Service is the delivery of computer hardware (servers, networking technology, storage, and data center space) as a service. Basically vendors builds the infrastructure compromising of server, load balancers, network cables, firewalls etc and then rent out this infrastructure to the organizations. Consumers does not manage the underlying infrastructure but has control over operating systems, storage and applications. Consumers can scale up  by requesting more servers or scale down as per their needs. Generally consumer is responsible for installing operating systems, applications and managing patches. Vendor is only responsible for managing lower level of stack.

Few examples of vendors providing IaaS are Amazon EC2, Windows Azure, Rackspace

Platform as a Service :
Platform as a Service comprises the environment for developing and provisioning cloud applications.  The PaaS offers black-box services with which developers can build applications on top of the compute infrastructure.The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages, libraries, services, and tools supported by the provider.  The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage, but has control over the deployed applications. The principal users of this layer are developers seeking to develop and run a cloud application for a particular platform. The vendor provides and manage everything, right from the network connectivity to the runtime.

The biggest advantage of PaaS is that developers can start creating the applications almost immediately.
You may not be able to do everything in PaaS that you can do in IaaS, but for the right fit PaaS will provide you with the ideal hosting environment.

The Windows Azure platform is the best example of  Platform as a Service. Windows azure doesn't provide access to the underlying environment like operating system, storage, firewall, networks.

Software as a Service:
In the Software as a Service , the service provider hosts the software so you don’t need to install it, manage it, or buy hardware for it. All you have to do is connect and use it. The applications can be accessible from various client devices through either a thin client interface, such as a web browser or a program interface. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.

Some of the examples of vendors providing SaaS are Salesforce, GoToMeeting, Google Apps, Microsoft Office 365

The primary benefit of Software as a Service is reduced cost for everyone involved.  Software vendors have to just maintain a single central copy of the product online. Users wouldn't have to shell out the large up-front costs of fully purchasing the product.

The risk of Software as a Service and cloud computing is that the users must place a high level of trust into the online software vendors that they will not disrupt the service.


When any organization switches to cloud computing, they must choose their software vendor very very carefully. By switching to cloud computing there will be large reduction in administration and other costs, but at the same time there will be increase in the risk of service disruption, connectivity, and online security.

Part 2 : Why use cloud

Clouds can provide users with a number of different benefits.

Many businesses iirespective of thier size are using cloud computing today  instead of traditional on-site alternatives. There are a number of reasons why cloud computing is so widely used among businesses today.

Access from anywhere : The biggest advantage of cloud is to provide access to your infrastructure, services, applications, data from anywhere in the world and that too 24/7.  In a way this is a greater freedom for the users of cloud as they can access applications and data from just about anywhere via multiple devices.

Reduction of Cost : Companies that use cloud computing do not incur the cost od start up. Unlike on-site hosting the price of deploying applications in the cloud can be less due to lower hardware costs.
Lets say there is a startup company which doesn't have any data center of it's own.
For such company , there are many costs to consider when they want to roll-out let's say new web site.
The major costs are:
Hardware :  web servers , database servers, routers, firewalls.
Software : licensing costs for all softwares.
Manpower : People to maintain and configure the servers.

Even after the initial effort, if the number of user base starts growing, the company has to provision new hardware to serve new users.

On the other hand if company uses cloud solution, they can start with minimum expenses. They don't have to purchase new servers. No need to purchase routers or firewalls, and no need to configure them.  There is no license to buy. There is no skilled manpower required to maintain the servers.

So all the initial cost in starting up the application is bypassed. You just need to pay for the usage of the application or site.
You can anytime scale up or scale down the server as per the users of your site increase or decrease.
You can also stop the site completely if not in use and not pay anything .

Up-to-date software's : A cloud provider will be responsible for upgrading the software and operating systems and apply patches as they released.

Flexibility : You can choose whatever software's you require, choose the RAM and disk space based on your requirements, and anytime scale them up or down, again based on the requirements.


However, large corporations are wary of cloud computing. There is a lack of trust between these corporations and storage providers. Even if some companies do trust their storage provider, they still have security concerns. Most big corporations are hesitant or unwilling to allow any of their sensitive data to be put in “the cloud.” There is always the possibility of hackers getting their hands on the data. In addition to that, users are not able to access the servers that have their stored data. Lastly, if the storage providers close up shop, it will be very hard to retrieve a company’s data.

Part 1 : Cloud Computing

Part 1 : Cloud Computing

In very simple terms cloud computing is all about delivery of computing resources over the internet. Instead of keeping data on your own hard drive or updating applications for your needs, you use a service over the Internet, at another location, to store your information or use its applications.

Cloud computing is the delivery of computing services over the Internet. Cloud services allow individuals and businesses to use software and hardware that are managed by third parties at remote locations. Examples of cloud services include online file storage, social networking sites, webmail, and online business applications. The cloud computing model allows access to information and computer resources from anywhere that a network connection is available.

Cloud computing provides a shared pool of resources, including data storage space, networks,computer processing power, and specialized corporate and user applications.
There may be several reasons that drive companies to adopt cloud computing service, with the primary reason being cost.

Small companies can't afford a large amount of hardware nor the staff that goes along with it. Large companies may find the costs of maintaining and managing their own datacenters to be prohibitive, or perhaps they have made a significant investment only to discover that much of their resources idling away.

Instead of hosting your company.s own e-mail or CRM (customer relationship management) software, you can choose to go with a third-party vendor. With services such as Salesforce or Gmail customized for your business (via a Google Apps domain), there's no need to even think of hardware.

There's a significant workload shift with cloud computing. 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.