Delivery Models

Found summary of the cloud service classification like Delivery models and Deployment models see previous post

Cloud services delivery can be broadly classified into three models. This is commonly called as SPI model.

1. Software as a Service (SaaS): Software applications delivered from the cloud using multi-tenancy and accessible by various devices using a web browser. The vendor controls the entire stack from hardware to applications with users having the control over their data.

2. Platform as a Service (PaaS): Application platform that completely abstracts all the complexities of the underlying infrastructure and delivered as a service for the users to deploy applications that can be accessed over the network. There are striations inside the PaaS itself with IDE as a service on one end to pure middleware as a service on the other end. For the sake of simplicity, we stick to the SPI model and consider various types of platform services within the PaaS categorization itself. The provider controls everything from hardware till the platform layer and users have complete control over their applications.

3. Infrastructure as a Service (IaaS): Raw compute power and storage offered as a service with a metered billing where users can deploy and run different software from operating systems to platforms to applications. Compared to PaaS, the abstraction is taken to a lower level in the infrastructure and users get more control over the configuration of platform itself. The provider manages the hardware and other infrastructure needed to run the virtual machines and the users get to control everything from OS to applications.