A1.1.9
Describe the different types of services in cloud computing
Organizations can access/utilize computing resources (servers, storage, databases) over the internet for flexible resources. Saves money — only pay for the…
Software as a Service (SaaS)
- Software applications hosted and managed by a third-party provider, accessed by organizations via web browser or mobile app over the internet.
- Eliminates the need to install/maintain software on your own devices → convenient, cost-effective.
- “Service” 指的是软件不用下载、不用安装、不用自己维护，直接在网上用就行。
Key Characteristics
- All-inclusive: full application suite with automatic updates/maintenance, no upfront cost.
- Scalability: easily scaled up/down to match changing needs.
- Accessibility: accessible from anywhere with internet → flexibility, mobility.
- Security: providers implement robust measures to protect data and ensure integrity.
Examples: Gmail, Canva, Google Sheets, Google Docs, Google Drive
Platform as a Service (PaaS)
- Provides a cloud-based environment for developers to build, deploy, and manage applications.
Key Characteristics
- DevOps-friendly: supports rapid dev/deploy cycles. (DevOps = combining software engineering (Dev) and information technology (Ops).)
- Infrastructure Abstraction: handles OS updates, database administration, networking config.
- Reduced operational costs: no need to purchase/maintain hardware/software.
Examples
- Heroku: fully managed platform — deploy apps by pushing code.
- Google App Engine: auto-scales and runs your app with minimal configuration.
- Firebase: backend-in-a-box — databases, auth, hosting without managing servers.
- Azure App Service: Microsoft’s fully managed environment for building/deploying/scaling web apps.
Infrastructure as a Service (IaaS)
- Provides virtualized computing resources (servers, storage, networking) over the internet.
- Businesses provision/manage their own IT infrastructure without investing in physical hardware/software.
Key Characteristics
- Customization: tailor (定做) IT structure to specific needs.
- Scalability: easily provision/scale resources.
- Control: full control over configuration and management.
Examples
- AWS: on-demand virtual servers — you control OS, storage, network.
- Azure Virtual Machines: scalable VMs where you manage everything above hardware.
- IBM Cloud Virtual Servers: secure, flexible VMs for enterprise workloads.
- Google Compute Engine (GCE): highly customizable VMs on Google’s global infrastructure.
Choosing the right cloud service model
| Feature | SaaS | PaaS | IaaS |
|---|---|---|---|
| Control | Lowest | Medium | Highest |
| Flexibility | Lowest | Medium | Highest |
| Resource Management | Provider manages everything | Provider manages most resources | Customer manages most resources (provider manages physical layer e.g. physical servers) |
| Cost | Most cost-effective | Medium | Most expensive |
| Suitability | Basic apps for general users | Rapid dev/deployment, custom apps | Specialized apps with hardware access |