cloud computing

Characteristics of Cloud Computing

• The key characteristics include:
    - Shared vs. Dedicated Resources:
      - Shared Resources:
        - Multiple customers use the same physical infrastructure (e.g., servers and storage).
        - Isolated via virtualization technologies to secure customer data.
        - Analogy: Apartment complex (shared common areas like pool but individual units).
      - Dedicated Resources:
        - Exclusive use by a single customer, providing better performance and enhanced security.
        - More expensive, suited for sensitive data regulations (e.g., financial institutions).
        - Analogy: Single-family home with private facilities.
    - Metered Utilization:
      - Cloud services use a pay-as-you-go model.
      - Charges incurred based on usage (storage, computing power, bandwidth).
        - Example: Renting a virtual machine for only the hours used.
      - Ingress Charges: Typically free; data entering the cloud.
      - Egress Charges: Costs incur for data leaving the cloud.
        - Example: Downloading backups or streaming data can incur fees.
    - Elasticity:
      - Resources can scale dynamically based on demand (e.g., online store traffic).
      - Prevents crashes during peak loads by automatically allocating resources.
      - Offers cost-effective resource management by only using what’s needed.
    - Availability:
      - Ability to access data and applications consistently.
      - High availability achieved through redundancy and geographic distribution.
        - Service Level Agreements (SLAs) often guarantee 99.9% uptime.
    - File Synchronization:
      - Keeping files updated across devices in real-time (e.g., document saved on one device accessible on others).
      - Examples: Google Drive, Microsoft OneDrive, Dropbox.
      - Requires stable internet connection; can consume bandwidth.
    - Multi-tenancy:
      - Multiple tenants share the same infrastructure, maintaining separate environments via virtualization.
      - Allows cost and resource efficiency.
        - Analogy: Hotel (private rooms with shared facilities).

Cloud Deployment Models

• Public Cloud:
    - Resources available to end-users over the Internet by providers (e.g., Google, Amazon, Microsoft).
    - Example: Google Drive.

• Private Cloud:
    - Internal cloud environment for exclusive organizational use (e.g., US GovCloud).

• Hybrid Cloud:
    - Combines benefits of public and private clouds with strict data management policies.

• Community Cloud:
    - Shared resources for organizations with common service needs.

Cloud Service Models

• Software as a Service (SaaS):
    - Complete solution provided to organizations, including hardware, software, and support.
      - Examples include Office 365, TurboTax, QuickBooks Online.

• Platform as a Service (PaaS):
    - Hardware and software platform provided for developing applications, while users handle application development.
      - Example: Development platforms hosted on AWS.

• Infrastructure as a Service (IaaS):
    - Provisioning of IT resources like servers and storage when needed, reducing long-term investment and management burdens.
      - Example: AWS EC2 instances.

Virtual Desktop Infrastructure (VDI)

• VDI hosts desktop operating systems on centralized servers.

• Access can be made from various devices (thin clients or web browsers), ensuring flexibility for users.
    - Models of VDI:
      - Centralized Model: All instances on one server.
      - Hosted Model: Maintained by a service provider (Desktop as a Service - DaaS).
      - Remote Virtual Desktop Model: Images copied to local machines before use, reducing bandwidth requirements.

• Benefits include centralized management and maintenance, while drawbacks involve reliance on network connectivity.

Cloud Storage Services

• Focus areas:
    - Cloud Storage Applications:
      - Examples: Dropbox, Google Drive, iCloud.
    - File Synchronization:
      - Ensures files are updated across connected devices (e.g., Google Drive syncing).
    - Content Delivery Networks (CDNs):
      - Distributed servers minimize latency and enhance performance across geographies.
        - Example: Video files uploaded to Google Drive are replicated worldwide for better access speed.