2. Cloud Computing

a. How Cloud computing works

Cloud means a grid of computers serving as a service-oriented architecture to deliver software and data. Most websites and server-based applications run on particular computers or servers. The applications are stored on these cloud and accessed by the user without knowing server configurations. A lot of the software that people use nowadays is completely web-based. For example, if you are hosting your website on a local server or from your PC, you must usually select a particular operating system (Windows/Linux/Mac), to determine what software you can run on that particular server. If your site is being hosted in the cloud, there is no need to do that. You can run Windows and Linux programs side by side.

 

b. Advantages of cloud computing

1. More Storage They can hold more storage than a personal computer can.  It takes away the need for the upgrading computer memory, which also helps keep the cost down for the companies and users alike.

2. Scalability - Cloud computing can be scaled to match the changing needs of your small business as it grows. You can quickly add additional licenses, storage space, and more as needed.

3. Device independent - Most web-based software and cloud services are not designed specifically for any one browser or operating system. Many can be accessed via PC, Mac, on tablets, and through mobile phones.

4. Cloud computing can be very quick and easy to get up and running.

5. Cloud computing is often cheaper and less labor-intensive for companies too. With a cloud company, there is no need to buy and install expensive software because it's already installed remotely and you run it from there. Additionally, these companies offer several cloud computing applications free of charge.

 

c. Types of cloud computing

Based on where the cloud is hosted also referred as Cloud computing Deployment models: 

1. Public cloud: This is standard computing model. The computing infrastructure can be shared between organizations having similar requirements. Public cloud service may be free or offered pay-per usage model. The customer has no visibility over the location of the cloud-computing infrastructure.

2. Private: Computing architecture is dedicated to the customer and is not shared with other organizations and managed internally or by a third-party and hosted internally or externally. They are expensive and are considered more secure than Public Clouds. 

3. Hybrid cloud: Hybrid cloud is a composition of two or more clouds (private, community, or public) that remain unique entities but are bound together, offering the benefits of multiple deployment models. It can also be defined as multiple cloud systems that are connected in a way that allows programs and data to be moved easily from one deployment system to another.

4. Community cloud: Community cloud shares infrastructure between several organizations from a specific community with common concerns (security, compliance, jurisdiction, etc.), whether managed internally or by a third-party and hosted internally or externally. The costs are spread over fewer users than a public cloud (but more than a private cloud), so only some of the benefits of cloud computing are realized.

 

Based on service provided:

1. Software As A Service (SAAS): This is the most common form of cloud computing. Complete software and its associated data are hosted centrally on cloud and are accessed by end users using web browsers over Internet. End users are charged on pay per use basis. Google Apps are one example of SAAS.

2. Infrastructure As A Service (IAAS): Hardware related services are provided using the principles of Cloud Computing. This includes servers, software, data-center space and network equipment, available in a single bundle and billed as per usage in a utility computing model. Amazon EC2, Amazon S3, Rackspace Cloud Servers are some of the leading vendors.

3. Platform As A Service (PAAS): It provides infrastructure on which software developers can build new applications or extend existing ones without the cost and complexity of buying and managing the underlying hardware and software and provisioning hosting capabilities. It provides all of the facilities required supporting the complete life cycle of building and delivering web applications and services PAAS layer lies between the SAAS and the IAAS layers. Some examples of PAAS are Goggle’s App Engine, and Microsoft’s Azure.