Cloud Service Models
Understanding IaaS, PaaS, and SaaS within the NIST Cloud Architecture.
Cloud computing services are categorized based on the level of control the user has over the underlying infrastructure and the degree of management provided by the service provider. These are commonly referred to as the "Service Models".
1. Infrastructure as a Service (IaaS)
IaaS provides the fundamental building blocks of cloud computing. It offers raw computing resources over the internet, such as virtual machines, networking, and storage.
- User Responsibility: The user manages the operating system, middleware, applications, and data.
- Provider Responsibility: The provider manages the physical hardware, servers, virtualization layer, and networking.
- Examples: AWS EC2 (Elastic Compute Cloud), GCP Compute Engine, and OpenStack for private clouds.
2. Platform as a Service (PaaS)
PaaS provides a framework that allows developers to create, test, and deploy applications without worrying about managing the underlying infrastructure.
- User Responsibility: The user manages only the application code and specific data.
- Provider Responsibility: The provider manages the hardware, OS, runtime environments, and middleware.
- Examples: AWS Lambda (Serverless), Google Cloud Functions, and tools for cloud development like CloudSim simulators.
3. Software as a Service (SaaS)
SaaS delivers complete, ready-to-use software applications over the internet on a subscription basis. This is the most common model for end-users.
- User Responsibility: The user only manages limited configuration settings within the app.
- Provider Responsibility: The provider manages the entire stack, from hardware to the software interface.
- Examples: Cloud AI services, IoT cloud services, and various business models for end-user applications.
Summary Table
| Feature | IaaS | PaaS | SaaS |
|---|---|---|---|
| Control | Maximum | Medium | Minimum |
| Complexity | High | Medium | Low |
| Target Audience | Network Architects | Developers | End Users |