There are many blogs and articles on the internet on cloud computing and perhaps there are too many. Yet the question keeps popping up. What is cloud computing ? Let us try to clear the fog around this topic.
Almost everyone uses online services like Gmail, Google docs, yahoo mail etc. To use these services, there is no investment to the consumer. There are no software licensing costs, there is no time spent in installing, managing, upgrading and software - not even client software. The infrastructure is provided and managed behind the scenes by providers like Google. Behind the scenes, Google adds the necessary hardware, upgrades the software when necessary, to ensure that you and I as end users get the same quality of service when we use Gmail. This is an example of what is called software as a service and is a form of cloud computing. Some companies do the same for enterprise software, the best example of which is SalesForce.com. Enterprise software is extremely hard to install and manage. With cloud computing, you can pay a fee and start using the software and let the provider take care of installation, management, maintenance and customization.
Companies like Amazon offer storage and servers that an IT department can use on demand. If I am running an IT department and all of sudden the enterprise needs several gigabytes of disk space or additional servers to run some additional jobs, I want to be able to rent the disk space or servers and use it temporarily - without an 18 wheeler bringing in boxes of hardware that I need to install, configure and manage. This is an example of the cloud offering computing services just the way utility companies offer electricity or water.
There are many more variations of this concept of providing some computing infrastructure whether hardware or software, over the internet for use by a customer.
Why is this stuff called the cloud ? The services we are talking about are generally offered over the internet. In computing literature, the cloud drawing is a popular way to show the internet as a computer network. The idea is that as a user you do not care about what is in the cloud, but you can reliably get some computing service from it. Cloud is an abstraction for the underlying computing technology which makes it easy to offer services in a highly dynamic and scalable manner. What distinguishes cloud computing from other forms of distributed computing is that one can view the cloud as vast supply of computing power, some of which you can buy for a fee.
If you are providing a cloud based service, a key requirement is that the architecture needs to dynamic. Depending on user demand, the provider should be able to scale seamlessly by adding hardware or software as necessary. This could be be anything from adding more storage or starting more server processes to handle user requests.
The consumer of the service should not have to do any infrastructure setup related to the service. Ideally the consumer should be able to use the service with minimal help from the provider. When you move into a new apartment or house, you call up the utility company to turn on the electricity service. After that you have uninterrupted service as long as you are paying your monthly bill. Using a cloud service should be as easy as that.
A good cloud platform is self managed and self healing. Services and usage are monitored and resources allocated optimally. Problems should be detected automatically and fixed without interruption of service.
Security for applications as well as data is critical for obvious reasons. Customers would suffer severe financial damages if their private data falls into the wrong hands.
So just putting up a web site that is hosted from your garage does not necessarily make you a cloud service provider.
The biggest advantage of cloud based services for the customer is that it provides a low cost entry point to a variety of computing services. Whether it is storage, web hosting, application services for email, documents to even things like payroll, to be able to get them with no infrastructure investment is a huge plus. Obviously, as with any out sourcing, you give up some control and become dependent on the service provider. However when you are starting out as a business, the lack of control might be tolerable when compared to the cost of setting up a data center or huge IT department. As the business grows and you have solid revenues, you can of course decide to move some function in house.
There are advantages for the service provider as well, especially for software.
If you have developed commercial software, you know how expensive it is to support several different versions. If your software is available as a cloud service, every user is on the same version.
Since users are not installing the software on their hardware, you do not have to support different platforms.
Since you control hardware and software, making updates/upgrades is easier. They can happen behind the scenes.
The application can to be tuned to the hardware/OS platform of your choice and hence can deliver the best performance.
To conclude, it is clear that the cloud computing paradigm does provide value to both customers and providers and it is not just a rehash of old technology - cloud service providers have to solve some real technical problems to ensure the quality of service for their customers.