Cloud Computing – integral part of our life

Whether we realize it or not, Cloud Computing has become an integral part of our life. When we are checking mails, are on social media, making train reservation, attending zoom calls, ordering food on Swiggy, watching Netflix, shopping on flipkart, chatting on whatsapp, using net banking, making online transactions, …. we are using cloud computing services. Cloud Computing has been a key enabler of Digital Transformation of the society.

According to the official NIST (USA) definition, "cloud computing is a model for enabling ubiquitous, 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."

In simple words Cloud Computing enables on-demand services like compute, storage, networking, etc. which can be accessed through the internet and the user is not required to manage these resources.

Essential Characteristics

The NIST definition lists five essential characteristics of cloud computing:

1. Pay as you go – pay for what you use

With cloud service, you don’t have to incur expenses on purchasing computing resources and you pay as your requirements grow. You also pay only for the time that you actually use and not for the time you don’t use.

2. Accessible from anywhere through internet

As cloud resources are accessed through internet, these can be accessed from anywhere where net connectivity is available. This gives great flexibility to users over on-premise computer systems.

3. User perceives infinite cloud

With Cloud, user can expect that his computational needs would be met with on-demand and systems can grow with infinite elasticity.

4. No human interaction

Another advantage of using cloud is that user requirements of resources can be met without any human intervention. 

5. Assign resources according to current demand

With cloud, the user needs to allocate only as many resources as are needed currently. Need for more resources will be catered to immediately. Similarly if the requirement reduces, extra resources can be released.

Advantages

Cloud computing allows companies to avoid or minimize up-front IT infrastructure costs. It also allows enterprises to get their applications up and running faster, with improved manageability and less maintenance, and that it enables IT teams to more rapidly adjust resources to meet fluctuating and unpredictable demand, providing the burst computing capability: high computing power at certain periods of peak demand.

Prominent Cloud Service providers are Amazon, Microsoft, Google, IBM, Oracle, etc with Amazon having the biggest share.

Deployment Models

The prominent Cloud deployment models are Public Cloud, Private Cloud and Hybrid Cloud.

Public cloud is like a public transport system – available to everyone. You can choose class of service, but not much flexibility. On other extremes is private cloud which is like your own car that can be used by your family members and have full flexibility. Hybrid cloud is like cab service that provides privacy and flexibility and doesn’t bring in cost of ownership.

Service Models

The three prominent service models are IAAS, PAAS & SAAS

IAAS or Infrastructure As A Service is a service where cloud service provider offers you computing resources like server, storage, etc and one can use them instead of physically purchasing them. For example, Amazon AWS provides servers through EC2 (Elastic Compute) and storage through S3 (simple storage) and EBS (block storage).

PAAS or Platform As A Service is a service where you get a platform for further development. It offers you development environment comprising of various tools and pre-built components and libraries. This greatly eases the IT needs of a SW development organization. Microsoft Azure is a development and deployment environment using the PaaS concept. Azure also supports a wide range of tools, languages, and frameworks. Azure supports the entire web app development life cycle, from build to deploy and thereafter.

SAAS or Software As A Service makes software available to users over the internet, usually for a user based subscription fee. With SaaS, you don’t need to buy whole SW and install and run it on your computer (or any computer). You subscribe to one available over internet and users use it by logging into their accounts online. This model is extremely useful for small organizations. For example, mail systems – like gmail or yahoo mail, conferencing solutions like zoom, etc.

We can see it with an example. If you move to a new city and want to prepare meal at the new home, you need to arrange for necessary infrastructure. If it was a furnished flat, you may get stove with piped gas supply, refrigerator, etc. along with flat (IAAS). If it was a serviced apartment, you may additionally get utensils, mixer/grinder, microwave oven and other tools – so that cooking can be done by you or someone you hire after arranging for ingredients (PAAS). You also have option of ordering food online and get it delivered at your new home (SAAS). You need to decide which option suits you!

Enabling Technologies

Cloud computing relies on sharing of computing resources to provide its services and economies of scale. I consider the following three technologies as pillars of Cloud Technology:

1. Virtualization,

2. Software Defined Networks (SDN)

3. Infrastructure as Code (IaC)

We’ll take up these three briefly here:

Pillar 1 - Virtualization

The key enabling technology for cloud computing is virtualization – a concept that deals with software emulation of hardware.

A virtual machine can be described as a software emulation of a computer machine. The computer machine on which this virtual machine (emulated computer machine) runs is generally referred to as the host, and the computer machine emulated on that host is generally referred to as the guest. A host can emulate several guests, each of which can emulate different operating systems and hardware platforms. A layer called hypervisor enables running of guest on host by translating their machine instructions. This emulated running of a guest on a host is called ‘virtualization’.