IaaS
IaaS stands for Infrastructure as a Service. This is also sometimes called Hardware as a Service (HaaS). This model allows you to outsource your hardware equipment. However, you’re still responsible for the management and security of the applications that run on the hardware. Web server providers are a common example of IaaS.
SaaS
SaaS stands for Software as a Service. SaaS provides on demand software. You log into a website and immediately have access to a particular software. For example, email distribution, like Google mail, is a common SaaS. Central management of data and applications are managed by the third party SaaS provider. With SaaS, no local installation or development work are required.
PaaS
PaaS stands for Platform as a Service. With PaaS, you’re in charge of building your own application, but that is all. You don’t need to worry about the servers, software, or the data center. You’re only in charge of putting together the development process for the application. You don’t have direct control of the data, people managing the applications, or infrastructure. PaaS is like building blocks. PaaS provides you with prebuilt modules for you to develop your own applications. You develop your own application based on what’s available on the cloud platform provided. Salesforce.com is an example of PaaS.
Public vs. private vs. hybrid vs. community
With a private cloud based deployment model, you have your own virtualized local data center. You would have your own hardware in your own data data center in an environment you control. Hardware is only used by a single company.
A public deployment model is available to everyone over the Internet. For example, Amazon web services is a public cloud model. In a public cloud, hardware is shared between multiple clients.
A hybrid deployment model is a mix of public and private. Some parts of your cloud services run in a private data center and other aspects of your cloud based service run in a public provider’s cloud.
A community deployment model allows you to share the cost and resources needed with the cloud by joining with a group of organizations to share the cost. The infrastructure is shared between several organizations with common concerns such as security, compliance, jurisdiction, etc.
