A1.1.10 Cloud Computing
What is Cloud Computing?
Using remote servers over the internet to store, manage, and process data instead of local hardware. Users only pya for the resources they use, rather than buying and maintaining physical infrastructure.
Service Models
| Model | What you get | You manage | Provider manages | Examples |
|---|---|---|---|---|
| SaaS Software as a Service |
Ready-to-use applications via a browser. | Nothing. | Everything. | Gmail, Google Docs, Canva, Salesforce |
| PaaS Platform as a Service |
Infrastructure + tools to build and deploy applications. | Your code and applications only. | OS, servers, networking, middleware. | Google App Engine, Heroku, Azure App Service |
| IaaS Infrastructure as a Service |
Virtualised servers, storage, and networking. | OS, software, apps, configuration. | Physical hardware only. | AWS, Microsoft Azure, Google Cloud, Linode |
Summary:
- SaaS — just use the app. Best for end users.
- PaaS — just write the code. Best for developers.
- IaaS — full control over infrastructure. Best for complex or custom IT needs.
Key Characteristics
| Feature | SaaS | PaaS | IaaS |
|---|---|---|---|
| Control | Lowest | Medium | Highest |
| Flexibility | Lowest | Medium | Highest |
| Resource management | Provider manages everything | Provider manages most | Customer manages most |
| Cost | Most cost-effective | Medium cost | Most expensive |
| Suitability | General use, basic apps | Custom apps, rapid development | Custom apps, specialised hardware needs |