Infrastructure as a service (IaaS), platform as a service (PaaS) and software as a service (SaaS) are the three main paradigms of cloud computing. It is important to understand the differences to make the right technology decisions for your enterprise.
Here’s a simple guide to the three cloud computing models:
- infrastructure as a service (IaaS)
- platform as a service (PaaS)
- software as a service (SaaS)
Infrastructure as a service (IaaS)
Infrastructure as a service is the most flexible cloud computing model. With infrastructure as a service, you have complete control over the infrastructure services like virtual machines, storage, networking and operating systems. This cloud computing model eliminates the need to buy hardware. Instead you will be renting the infrastructure and accessing it over the internet.
Infrastructure as a service is a shared responsibility model with the cloud services provider (CSP). The CSP ensures that the service is highly available. It is end customer’s responsibility to patch and upgrade the system.
Common use cases for infrastructure as a service are:
- Migration of applications from on-premises to the cloud
- Running development and testing environments
- Backup
- Storage
Examples includes: Microsoft Azure, AWS EC2, Google Cloud Platform
Platform as a service (PaaS)
The second cloud computing model is platform as a service which allows enterprises to develop, test and deploy their applications without managing the underlying infrastructure. For example, you can deploy a web application without installing the operating system and worrying about upgrading the system.
PaaS is sometimes called ‘middleware’, referring to how it conceptually sits somewhere between SaaS and IaaS. Platform’s like Google’s App Engine, IBM BlueMix, and Apache’s Stratos are popular PaaS products which are helping to streamline and democratize software development.
Cloud benefits like scalability, high availability and resiliency are built in these services.
Software as a Service (SaaS)
Software as a service is the third cloud computing model where an application is centrally hosted and offered as a subscription to the end users. Some examples of SaaS are Salesforce CRM, Office 365, Box, Google Apps, Netflix. Enterprises can quickly realize value with minimal management with SaaS.
IMPORTANT: All IaaS, PaaS and SaaS have service level agreements and it is important to fully understand them.
The table below depicts the customer’s responsibilities within each cloud computing model:
