Cloud Computing Service Models

Overview

• Service models are foundational to cloud computing.
• They enable the delivery of services to customers.
• Three basic service models:
  • Infrastructure as a Service (IaaS)
  • Platform as a Service (PaaS)
  • Software as a Service (SaaS)

Software as a Service (SaaS)

• Provides end-users with access to applications as services rather than on-premises software.
• Includes packaged software, operating systems, application stack, server, storage, and networks.

Platform as a Service (PaaS)

• Designed for application developers to build and deploy custom applications.
• Includes middleware, operating systems, application stacks, server, storage, and networks.

Infrastructure as a Service (IaaS)

• Focuses on providing computing infrastructure such as hardware, server, storage networks, and architecture.
• Allows customers to use infrastructure rather than having their own dedicated infrastructures.

Key Characteristics of IaaS

• Host: Acts as a host providing virtual machines and storage.
• Scalability: Infrastructure is scalable based on processing and storage needs; pay-as-you-go model.
• Virtualization: Resources are available via server virtualization.
• Examples: Amazon Web Services, GoGrid.

Advantages

• Users pay on-demand instead of purchasing hardware outright.
• Scalable: Pay less for less usage and more for higher usage.

Issues with IaaS

1. Compatibility with Legacy Systems
   • Supports legacy software which may expose security vulnerabilities.
2. Virtual Machine Sprawl
   • Virtual machines can become outdated with security updates.
   • Complex maintenance for automatic updates.
3. Robust Virtual Machine Isolation
   • Offers isolated environments through hypervisors.
4. Data at Rest Practices
   • Ensures next customers do not access data of previous customers on shared resources.