Cloud Computing Explained

Traditional infrastructure

1. Create a physical infrastructure Layer – They will have to buy 100s of servers, networking equipments, storage devices on which they will have to build their infrastructure. On top of that they will have to  buy space to accommodate the servers and equipments, power with backup, cooling. They will also need to upgrade their servers after every few years.
2. Create Platform layer –  To utilize the hardware resources they will have to acquire software like OS, web-servers, application servers, databases, CDN, caching, etc. These software will have to  installed on each of the groups of servers and maintained regularly.
3. Create the Application – Then the company will have to hire a dedicated team of developers who will develop the actual system to be installed on platform created above.

Cloud Segments:

As we saw that there are three distinct layer of any application infrastructure. These are physical layer, platform layer, and application itself. Cloud products falls exactly in these three layers and thus cloud services are classified into three segments.

1. Infrastructure as a service or IaaS – This is delivering of hardware ie, CPU, memory, storage, networking as a service. In other words users can provision these hardware resources without buying the actual device, they can use the online application provided the cloud to get these delivered as a service. For example Amazon EC2 allows users to create compute units with desired OS, RAM, CPU and storage via their console. So Amazon EC2 is a IaaS.  Other examples are Google Compute Engine, AWS S3, AWS ELB, Route 53, IBM Smartcloud, Microsoft Azure IaaS.
2. Platform as Service or PaaS – Platform as a service provides the software environment which is required to run an application, as a service . For example to run a simple java web-application you require to install Tomcat on your computer. In addition you may also require a database. So a computer with tomcat and database becomes a platform in which a java web-application can run. Any cloud service which delivers this platform over the network can be classified as PaaS. Example of PaaS is Amazon Elastic Beanstalk. Beanstalk comes pre-configured with apache/tomcat/php and a database. It provides APIs using which you can deploy your application on it without worrying about what is installed there. Examples of PaaS providers are Amazon Elastic Beanstalk, Elastic Cache, SQS, SES, SNS, Google App Engine, Microsoft Azure, VMware Cloudfoundry etc.
3. Software as a Service or SaaS – Last but not the least we have SaaS.  SaaS delivers application as a service. For example http://zencoder.com/ is a SaaS application which delivers video transcoding service over the web. As a user all you need is to create an account and access the service. You don’t need to pay any money upfront and pay only for resources you consume while transcoding. Some examples of SaaS are Google Apps, salesforce.com, Amazon Elastic Transcoder, Kikapps, Gigya, Janrain etc.

So now we see how different layer of cloud computing maps with different layer of traditional infrastructure

• Physical Layer = Infrastructure as a Service (IaaS)
• Platform Layer = Platform as a Service (PaaS)
• Application Layer = Software as a Service.

https://www.javacodegeeks.com/2013/06/introduction-to-cloud-computing.html