Every few years there are technological innovations that change the entire landscape and ecosystem around them. If we go back in time, the 70's and 80's was a time of mainframes. They were huge in size, practically occupying large rooms and almost all computing work was carried out by them. It was difficult to procure one and it was also time-consuming. Enterprises used to order months before they could have an operational mainframe set up.
The first part of the 90's was the era of personal computing and the internet. Computers became much smaller in size and were comparatively easier to procure. Both personal computing and internet innovation changed the entire computer industry. People had a desktop through which they could run multiple programs and could connect to the internet. The rise of the internet also propagated the rise of client-server deployments. Now, there could be centralized servers hosting applications and services that could be reached out by anyone who had a connection to the internet globally. This was also when server technology got a lot of prominences. Windows NT, Windows 2000, and Windows 2003 were launched during this time.
The most remarkable innovation of the 2000's was the rise and adoption of devices, especially smartphones, and with them came a plethora of apps. Apps could connect to centralized servers on the internet and could carry out business as normal. Users were no longer dependent on browsers to make this work. All servers were typically either self hosted or hosted with a service provider, such as an Internet Service Provider (ISP).
Users did not have much control over their servers. Multiple customers and their deployments were part of the same server even without customers knowing about it.
However, there was something else happening towards the mid and later parts of the 2000's. This was the rise of cloud computing and it again rewrote the entire landscape of the IT industry. Although, initially the adoption was slow and people approached it with caution either because the cloud was in its infancy and yet had to mature or people were having multiple varied diverse notions about it.
Nevertheless, today cloud computing is one of the most promising and still upcoming technology and enterprise--no matter how big or small, every company/organization has adopted it as a part of their IT strategy. It is difficult these days to have any meaningful conversation without including cloud computing in the overall solution discussions.
Cloud computing, or simply cloud in layman terms, refers to the availability of resources on the internet. These resources are made available to users on the internet as services. For example, storage is available on-demand through the internet to users for them to store their files, documents, and so on. Here storage is a service provided by a cloud provider.
A cloud provider is an enterprise or consortium of companies that provide cloud services to other enterprises and consumers. They host and manage the services on behalf of the user. They are responsible for enabling and maintaining the health of services. Typically, there are large data centers across the globe opened by cloud providers to cater to IT demands from users.
Cloud resources could be a delivery of hosting services or providing on-demand infrastructures, such as a computer, network, and storage facilities to users for consumption. This flavor of the cloud is also typically known as Infrastructure as a Service.
There are three types of services provided by cloud based on their level of abstraction and degree of control on these services by users and cloud providers:
- Infrastructure as a Service (also popularly known as IaaS)
- Platform as a Service (also popularly known as PaaS)
- Software as a Service (also popularly known as SaaS)
IaaS, PaaS, and SaaS differ based on the level of control between a cloud consumer and a cloud provider. With SaaS, a cloud provider has almost complete control over the services with the consumer having control only over its data and application. Similarly, a cloud provider has higher control with IaaS as compared to cloud consumer.
The preceding diagram shows the three categories of service available through cloud providers and the layers that are comprised of each service. These layers are stacked vertically on each other and each layer in the stack is colored differently depending on who manages it, the customer or the provider. From the figure, we see that for IaaS, a cloud provider is responsible for providing, controlling, and managing layers from the network layer up to the virtualization layer. Similarly, for PaaS, a cloud provider controls and manages from the hardware layer up to the runtime layer, while the consumer controls only the application and data layers.
