Dinesh on Java

Platform as a Service, often simply referred to as PaaS, is a category of cloud computing that provides a platform and environment to allow developers to build applications and services over the internet. PaaS services are hosted in the cloud and accessed by users simply via their web browser.

Platform as a Service (PaaS) delivers application execution services, such as application runtime, storage, and integration for applications written for a pre-specified development framework. PaaS provides an efficient and agile approach to operate scale-out applications in a predictable and cost-effective manner. Service levels and operational risks are shared because the consumer must take responsibility for the stability, architectural compliance, and overall operations of the application while the provider delivers the platform capability (including the infrastructure and operational functions) at a predictable service level and cost.

Platform as a Service allows users to create software applications using tools supplied by the provider. PaaS services can consist of preconfigured features that customers can subscribe to; they can choose to include the features that meet their requirements while discarding those that do not. Consequently, packages can vary from offering simple point-and-click frameworks where no client side hosting expertise is required to supplying the infrastructure options for advanced development.

The following diagram shows how PaaS offers an API and development tools to the developers and how it helps the end user to access business applications.

Benefits of PaaS cloud computing layer

1) Simplified Development
Developers can focus on development and innovation without worrying about the infrastructure.

2) Lower risk
No requirements of up-front investment in hardware and software. Developers only need a PC and an internet connection to start building applications.

3) Prebuilt business functionality
Some PaaS vendors also provide already defined business functionality so that users can avoid building everything from very scratch and hence can directly start the projects only.

4) Instant community
PaaS vendors frequently provides online communities where developer can get the ideas, share experiences and seek advice from others.

5) Scalability
Applications deployed can scale from one to thousands of users without any changes to the applications.

Disadvantages of PaaS Layer

1) Vendor lock-in
One have to write the applications according to the platform provided by PaaS vendor so migration of an application to another PaaS vendor would be a problem.

2) Data Privacy
Corporate data, whether it can be critical or not, will be private so if it is not located within the walls of the company there can be a risk in terms of privacy of data.

3) Integration with the rest of the systems applications
It may happen that some applications are local and some are in cloud. So there will be chances of increased complexity when we want to use data which in the cloud with the local data.

PaaS Types
Based on the functions, the PaaS can be classified into four types as shown in the following diagram:

Top vendors who are providing PaaS cloud computing platform

• Google Apps Engine (GAE)
• SalesFroce.com
• Windows Azure
• AppFog
• Openshift
• Cloud Foundary from VMware

References

1. http://en.wikipedia.org/wiki/Platform_as_a_service