What is Cloud Computing?
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WHAT
Imagine for a moment that you have purchased a house and you want to have water service. So, you start digging in the yard searching for a source of water and, when you find it, you begin the installation of pipes and a water pressure pump to get this vital fluid though the piping system to reach all the areas of your new house. Would you do all this? Of course not, the obvious way of proceeding is to make a contract with the City Water Service and just connect to it. You do not need to have your own infrastructure to get the water out of the ground to your house. With cloud computing you do not need to have a bunch of servers in your premises. You “contract” such resources from a cloud computing hosting company and just connect your local PCs and other equipment. The main source of computer power is not in your site but in the “cloud”, somewhere in the world.
HOW
To start using cloud resources it is necessary to find a provider like Amazon Web Services, Microsoft Azure, Google Cloud, or any other of your choice. Such providers allow selecting the needed computational configuration and, in a matter of a few minutes, you have a brand-new server or service. This approach avoids purchasing new machines, storage devices and software; and the time needed to install, configure and test is dramatically reduced. Also, it is possible to scale horizontally and scale vertically the computational power according to what you require. Scale vertically means that you can increase and decrease the power of the actual resources while scale horizontally means that you can increase and decrease the number of devices. For example, an online retail company can increase the number of web servers (scale horizontally) on holiday seasons like Christmas and New Year, and add load balancing service so that all servers get the same amount of work, and later take those extra servers down when sales come back to normal. As you may have already guessed, payment is only done for the resources you contract so you are not necessarily tied to a fixed time frame. One great feature of cloud computing is that all the configuration procedures are self-served, they are done through a friendly interface. Such an interface allows to select parameters like CPU type, amount of main memory, storage space and operating system, for example. Many other services might be offered like database, inexpensive backup storage, email, virtual private networking, messaging, and many more.
SERVICE MODELS
Cloud computing offers several service models:
- Infrastructure as a Service (IaaS)
Includes the provision of processing power, storage, networking and other computational resources. Basically, IaaS refers to the hardware needed to run arbitrary software. Examples are servers, storage devices and networking hardware. Your IT hardware infrastructure is in the cloud not in your premises. Many hosting companies include redundancy. For example, when you lease a virtual server in Amazon Web Services, you actually get your machine plus 2 backup servers. In case of failure, a backup server starts working transparently while the original is replaced.
- Platform as a Service (PaaS)
Includes the deployment of software that provides support to develop, run and manage applications. Examples are database management systems, web server software, email server software, and software development tools. Your platform software is in the cloud, running on your IaaS. An advantage is that you do not have to worry about software licensing, its cost is included in PaaS.
- Software as a Service (SaaS)
Includes the usage of end-user applications that are accessible from many client devices through a user interface. Examples are customer relationship management apps (CRM), online documents management (Google Docs), inventory control systems, games. All this software is installed in IaaS running over PaaS resources.
CONCLUSION
In summary, cloud computing offers “computational hardware and software resources for lease”. Such resources can be scaled according to your requirements and at the time you need, and you only pay for what you actually consume. There is no need to worry about important issues like obsolete equipment, server redundancy and software licensing.