Cloud computing is a style of computing in which resources are made available over the internet. Most often these resources are extensible and highly visualized resources and they are provided as a service. Cloud computing is broken down in to few different categories based on the type of service provided. SaaS (Software as a Service) is the category of cloud computing in which the main resources available as a service are software applications. PaaS (Platform as a Service) is the category/application of cloud computing in which the service providers deliver a computing platform or a solution stack to their subscribers over the internet.
What is PaaS?
PaaS is the category/application of cloud computing in which the service providers deliver a computing platform (a hardware architecture and a software framework) or a solution stack (computer subsystem needed to run a software). This makes it possible for the subscribers to deploy an application without having to buy and manage the necessary software and hardware requirements. The responsibility of maintaining the necessary hardware, operating systems, helper applications and databases is the sole responsibility of the service provider. The PaaS subscribers can make use of the delivered platform to build and ultimately deliver web applications and services. PaaS services typically offer complete set of facilities for designing, developing, testing and deploying applications to team collaboration, web service and database integration, version control and configuration management of software. All these facilities are usually available as a single integrated development environment making it very convenient to the developers or the users. Four popular types of PaaS are Add-on, Stand alone, delivery-only and open platform PaaS.
What is SaaS?
SaaS is one of the categories/methodologies of cloud computing. As mentioned above, resources available as a service through SaaS are specifically software applications. Here, an application is shared across multiple clients using the “one-to-many” model. The advantage offered for the SaaS user is that she can avoid installing and maintaining software and can free herself from complex software/hardware requirements. The provider of SaaS software, also known as hosted software or on-demand software, will take care of the security, availability and performance of the software because they are run on the provider’s servers. Using a multitenant architecture, a single application is delivered to millions of users through internet browsers. Customers do not require upfront licensing while providers are enjoying a lower cost because they are maintaining just one application. Popular SaaS software are Salesforce.com, Workday, Google Apps and Zogo Office.
What is IaaS?
IaaS: When the cloud computing system that is offered to you provides you with only infrastructure or the actual hardware (servers and disks), the system is essentially a IaaS. What you get is an infrastructure. You are responsible for installing all the required platforms on top of it. You are responsible for upgrading the necessary platforms if there is a new version released in the market. Let’s say you have installed the .NET Platform on IaaS. Whenever Microsoft releases a new version of .Net, you as an end user of the cloud computing system, take full responsibility of upgrading the system to a newer version of the .Net. It might require you to completely bring your website running on the cloud down, to complete the upgrading process and you will have to live with it
What is the difference between PaaS and SaaS?
Even though, PaaS and SaaS are two applications/categories of cloud computing, they have their key differences. PaaS is the category/application of cloud computing in which the service providers deliver a computing platform or a solution stack, SaaS focuses on specifically making software applications available over the internet. Important difference between these two services can be identified from the type of subscribers. PaaS is typically used by application developers, while SaaS is used by end users. In other words, PaaS provides a mechanism to develop applications whereas SaaS provides already completed products for the use of the subscribers without modifications.
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