Cloud Computing Basics

Defining a Cloud

• Cloud computing enables on-demand, network access to a shared pool of configurable computing resources (e.g., networks, servers, storage).
• Services are accessible via web browsers or web services APIs, ensuring easy connectivity.
• No initial capital expenditure is required; users pay only for what they consume.
• Defined by the ability to dynamically provision interconnected and virtualized computers, presented as unified resources under service-level agreements (SLAs).

Leading Examples of Cloud Service Users

• Large enterprises offload activities to cloud systems, enhancing efficiency and reducing costs.
• Small businesses and startups can quickly convert ideas into actionable business results without heavy upfront investments.
• Developers focus on business logic, free from the complexities of infrastructure management.
• End users can access documents from various devices and locations, improving convenience.

Characteristics and Benefits

• Cloud computing eliminates up-front commitments, allowing for agile business practices.
• Offers on-demand access, empowering users to deploy services as necessary.
• Flexible pricing models contribute to cost savings and resource efficiency.
• Accelerates application deployment and provides scalable resources.
• Seamless integration with third-party services enhances functionality.
• Promotes energy efficiency through optimized resource allocation.

Challenges Ahead

• Legal complexities arise from the global distribution of cloud infrastructure, creating potential compliance issues with varying privacy laws.
• Data security is a major concern; organizations lack control over the infrastructure, posing risks for confidential information.
• Practical challenges involve configuring and sizing cloud systems effectively to meet dynamic demand, particularly in Infrastructure-as-a-Service scenarios.
• Technical challenges exist for cloud providers in managing large-scale infrastructures and optimizing virtualization technologies.

History of Cloud Computing

• Five core technologies have shaped the development of cloud computing:
  • Distributed systems
  • Virtualization
  • Web 2.0
  • Service orientation
  • Utility computing
• Key milestones in cloud computing evolution include:
  • Mainframe computing
  • Cluster computing
  • Grid computing

Cloud Reference Model

• The cloud reference model organizes cloud computing services into distinct layers: IaaS, PaaS, and SaaS.
• Core middleware manages physical infrastructure, optimizing application environments and resource utilization.

Infrastructure as a Service (IaaS)

• Utilizes virtualization technologies to customize runtime environments, application isolation, and quality of service.
• Hypervisors manage resources, exposing them as a collection of virtual machines for efficient resource allocation.
• IaaS is typically categorized into two types:
  • IaaS providing both management layer and physical infrastructure
  • IaaS (M) providing only the management layer, usually combined with physical IaaS solutions.
• IaaS solutions primarily focus on system infrastructure design, offering limited application development capabilities.

Platform as a Service (PaaS)

• Encompasses cloud programming environments and tools that improve application development on cloud platforms.
• Tools include web-based interfaces, command-line tools, and frameworks designed for concurrent and distributed programming.
• PaaS provides a development platform through user-level middleware, making cloud-specific application development possible.
• In Pure PaaS, only user-level middleware is offered, necessitating external infrastructure.

Software as a Service (SaaS)

• The top layer of the cloud reference model, primarily consisting of web-based applications delivered via the cloud.
• Cloud-powered SaaS applications allow independent software vendors to serve users over the Internet, enhancing scalability and accessibility.
• Examples include gaming portals and social networking websites that utilize cloud infrastructure for expanded user support.

Virtualization and Distributed Systems

• Hardware virtualization is the foundation for IaaS and facilitates the creation of virtual machines for distributed systems.
• Virtual machines are priced according to their virtual hardware features: memory, processors, and disk storage.

Management Layers

• The three principal layers of an IaaS solution are:
  • Physical Infrastructure: Basic hardware level.
  • Software Management Infrastructure: Contains management functions for virtual machines and services.
  • User Interface: Offers access to management services via Web 2.0 technologies, including RESTful APIs and web services.

Core Features and Components of IaaS

• Management of virtual machines is paramount, with the scheduler playing a critical role in allocating VM resources.
• Key components of the infrastructure management software layer include:
  • Pricing and Billing Component: Manages costs associated with VM execution and user charges.
  • Monitoring Component: Tracks VM performance data for analysis and reporting.
  • Reservation Component: Maintains records of executed and scheduled VM instances.