Before moving into the cloud you need to make two specific decisions. The first is determining the service model on which you will host your application(s), for example IaaS, PaaS or SaaS. Each of these service models require various levels of support and responsibilities once a system is deployed to the platform
The summary of these terminologies is as follows –
- IaaS – Infrastructure as a Service – a set of infrastructure level capabilities such as an operating system, network connectivity, etc. that are delivered as pay for use services and can be used to Host applications. Example, Azure VM, VNET.
- PaaS – Platform as a Service – is about abstracting developers from the underlying infrastructure to enable applications to quickly be composed. This is specifically for developers who are willing to Build applications without worrying about management of hosting environment at all. Example, Azure Cloud services, Azure Web Apps, Storage, SQL Azure Database and so on.
- SaaS – Software as a Service – applications that are delivered using a service delivery model where organizations can simply Consume and use the application. Typically, an organization would pay for the use of the application or the application could be monetized through ad revenue. Example, Office 365, Gmail, Saleforce.com, SharePoint online, CRM online and so on.
Following diagram explains important difference between IaaS, PaaS and SaaS.
As you can see from the above diagram, more you go towards right hand side of the graph things that you manage become lesser and lesser. In SaaS typically you don’t manage anything and just consume. At the max you can make look and feel or configuration changes but everything rest is managed by Microsoft Azure for you.
*** Thanks to Kunal Chandratre and Vikram Pendse for this topic