Definition
Some would say that the cloud is still being defined. In some extent this is correct provided the evolutive aspect of the concept. The thing is, many of the Internet users are already cloud users without knowing it. Webmail service is a perfect example of cloud services.
Let's first look at the definition given by the National Institutes of standards and Technology (NIST) :
"Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction."
We can already see that this applies to one's gmail, yahoo, hotmail, ... account used through the web.
You get an access to the service by your self through your Internet browser, just with few clicks and it is operational.
But do you know where your data are actually stored. That could be anywhere but you don't care. This where the whole cloud philosophy lies in.
History
It is not by chance that cloud computing has been developing considerably over these past few years. The cloud is actually the 5th generation coming in the IT landscape. The cloud find its essence in the past 4 generations:
1rst generation: Mainframe
In the 1960's, mainframes were the solution for bulk data and back office processing. As this technology was very expensive, it has been first used by both corporate and governmental organizations for critical tasks like batch billing and census operations. Users where generally connected to the mainframe through passive terminals to execute jobs.
Later on modern mainframes were used for their powerful performance with the development of e-business.
2nd generation: PC
The PC is intend to be used by the end user with no intervention of a computer operator. Reduction in size and sales price made this technology accessible for individual use. Desktop computer spread in the corporate environment and workgroups networking developed to address the resource sharing in offices.
3rd generation : Client/server architecture
Client server/ architecture addressed again the resource sharing and data centralization issues.
However, the spread of automation and process application through corporations raised a new issue: System integration. IT systems needed to communicate with each other in order to fulfill actions engaging multiple departments each using it is own business supporting application.
ERP was a concept answering this need however such solution is out of reach of mid size businesses.
4th Generation: Dynamic Web, Web 2.0, SOA, Virtualization
the 4th generation comes with four major concepts that revolutionized the web and the IT landscape within corporations.
- Dynamic web made possible the web page generation or change on the client side according to the interaction of the user.
- Web 2.0 made it possible for me as web user not only to consume content made available but also to put in and enrich with my own content and to interact with other users. More generally web 2.0 allows the use of the web site as content sharing and social media interaction platform.
- SOA this concept made even the interaction between multiple application as simple as web querying of published services.
- Virtualization made it possible to run application on different OS but simultaneously on a single server
5th generation Cloud computing:
Here comes the cloud as the 5th generation taking its essence from past evolutions and evolving needs and concerns.
The spread of computers and last evolutions like virtualization and SOA contributed to the development of the cloud concept to adress the need of fast deployment and resource pooling:
- Most of businesses perceive their IT department as a cost center and not able to keep up with fast changes induced by the rapid market mutation and harsh competition.
- Needs in terms of capacity may vary over the year and according to the activity nature so that investments in additional hardware are most of the time used at 100% only on a limited period of the year
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