Layered Cloud Architectural Development
Cloud architecture is developed in three layers:
1. Infrastructure Layer (IaaS):
- Virtualized compute, storage, and network resources.
- Handles provisioning and resource abstraction.
2. Platform Layer (PaaS):
- Provides software tools and environment for application development.
- Ensures scalability, security, and dependability.
3. Application Layer (SaaS):
- Includes software modules for:
- Document editing
- Calendar/authentication
- CRM
- Financial transactions, etc.
Layer Dependency:
- Layers are built bottom-up (IaaS → PaaS → SaaS).
- Some services may span multiple layers.
Provider Workload:
- SaaS: Most workload for providers.
- PaaS: Medium.
- IaaS: Least workload.
Example: Amazon EC2 (IaaS), Salesforce CRM (SaaS + PaaS + IaaS).
Market-Oriented Cloud Architecture
To meet consumer demands and QoS (Quality of Service):
- SLAs (Service-Level Agreements) define QoS.
- Market-based resource management balances supply and demand.
Main Components:
- Users/Brokers: Submit service requests.
- SLA Resource Allocator: Interfaces with users and assigns resources.
- Service Request Examiner: Checks QoS and accepts/rejects requests.
- Pricing Mechanism: Charges based on usage, peak/off-peak hours.
- Accounting: Tracks actual resource usage.
- VM Monitor: Monitors VM availability.
- Dispatcher: Executes requests.
- Service Request Monitor: Tracks execution.
VM Flexibility:
- Multiple VMs can run different OSes on one physical machine.
- VMs are isolated and dynamically scalable.
