IaaS, PaaS, SaaS
These are the three primary models of cloud computing service delivery. Each offers a different level of abstraction, control, and responsibility for infrastructure and applications.
IaaS – Infrastructure as a Service
Definition: IaaS provides virtualized computing resources over the internet. It offers the most control to users over infrastructure but requires management of the operating system, middleware, and applications.
Characteristics
Provides VMs, networking, storage, and firewalls
Users manage OS, runtime, and applications
Flexible and scalable
Pay-as-you-go pricing
Examples
AWS EC2
Google Compute Engine
Microsoft Azure Virtual Machines
OpenStack
Use Cases
Hosting custom web apps
Migrating on-premises workloads
Building testing/staging environments
PaaS – Platform as a Service
Definition: PaaS offers a ready-to-use development and deployment environment. It abstracts infrastructure management, allowing developers to focus on application logic.
Characteristics
Manages runtime, OS, servers, and storage
Developers focus on code and configuration
Supports CI/CD, scaling, and monitoring
Reduces operational overhead
Examples
Google App Engine
Heroku
AWS Elastic Beanstalk
Azure App Services
Use Cases
Rapid application development
Deploying web apps without managing servers
Supporting microservices architecture
SaaS – Software as a Service
Definition: SaaS delivers fully functional applications over the internet, accessed via a web browser. Users don't manage any infrastructure or platform components.
Characteristics
Ready-to-use software applications
Managed entirely by the vendor
Subscription-based or freemium pricing
Accessible from anywhere
Examples
Google Workspace (Gmail, Docs)
Microsoft 365
Salesforce
Dropbox
Use Cases
Email and collaboration tools
CRM and ERP systems
File storage and sharing platforms
Comparison Table
User Control
Full (OS, runtime, apps)
App-level (code, config)
Minimal (just app use)
Management Level
High
Moderate
Low
Flexibility
Maximum
Medium
Low
Target Users
Sysadmins, DevOps, SREs
Developers, App engineers
End users, Business teams
Responsibility
You manage most resources
Provider manages platform
Provider manages everything
Conclusion
IaaS is ideal for teams needing full control and flexibility to configure infrastructure.
PaaS is suitable for developers focused on building and deploying applications quickly.
SaaS fits end-users who need ready-to-use applications with minimal management.
Let me know if you want this documented in a PDF or compared with container-as-a-service (CaaS) and function-as-a-service (FaaS) models.
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