AZ-900 Certification Notes

Chapter 2.3 - Cloud Service Models

Infrastructure-as-a-Service (IaaS)

• Infrastructure = actual servers
• Scaling is fast
• No ownership of hardware IaaS offers VMs & Servers, Storage, Networking components, firewall and the physical hardware everything runs on.

Platform-as-a-Service (PaaS)

• Superset of IaaS
  • Offers all that IaaS
    • Also offers Middleware, development tools, business intelligent, services, database management systems, and more.
• PaaS supports web application life cycle
• Avoids software license hell

Software-as-a-Service (SaaS)

• Providing a managed service
  • Provides all that PaaS and IaaS provides
    • Also offers apps/software
• Pay an access fee to use
• No maintenance and latest features

Serverless

• There are servers, this just means you don't have to manage any servers. You are using someone else's servers
• Azure Functions is the best know serverless service
• Extreme PaaS

Identifying Cloud Service Models

• IaaS
  • Organization has complete control of the infrastructure
  • Dynamic and flexible. You can do almost anything.
  • Cost varies depending on consumption
  • Services are highly scalable
  • Multiple users share a single piece of hardware
  • Examples:
    • VM
    • VNet
    • Storage
• PaaS
  • Resources are virtualized and can easily be scaled up or down as needed
  • Services often assist with the development, testing, and deployment of apps
  • Multi-user access via the same development application
  • Integrates web services and databases
  • Examples:
    • App Services
    • Azure CDN
    • Cosmos DB
• SaaS
  • Managed from a central location
  • Hosted on a remote server
  • Accessible over the internet
  • Users not responsible for hardware or software updates
  • Rate limiting/QoS
  • Examples:
    • Microsoft 365

Exam Tips

Service is the core of Azure, and there are three main ways to go about it.

• IaaS provides servers, storage and networking as a service
• PaaS is a superset of IaaS and also includes middleware, such as database management tools
• SaaS is when service is built on top of PaaS, like Office 365
• Serverless means that you don't have any servers. Let's a single function be hosted, deployed, run and managed on its own