Cloud concepts

• Management of hardware and software by a third party
• The computer is in a data center instead of at your company
• Flexibility to add or remove resources (ram, computing, etc)
• Pay for what you use!
• Lift and shift: move to cloud
• Benefits:
• Economy: Pay as you uso. Cost prediction
• Agility: Quick to deploy
• Availability: Always up
• Scalability: Vertical (add more cpu). Horizontal (Add more servers)
• Elasticity: Grow or shrink based on demand
• Actual: Infraestruture always updated
• Reliability: Availability, redundancy, fault tolerance
• Global: Servers around the world and low latency
• Security: Physical and digital

Concepts

• High availability

• The ability of a system to respond to users (in percentage)

• 99,99%: 4 minutes a month of down time

• Scalability

• Ability of a system to handle growth of users or work

• Elasticity

• Ability of automatically grow and shrink based on application demand

• Agility

• Ability to change rapidly based on changes to market or environment

• Fault tolerance

• Ability of a system to handle faults like power, networking or hardware failures

• Disaster Recovery

• Ability of a system to recover from failure within a period of time, and how much data is lost

• Economy of scale

• It's cheaper for a Cloud Provider to run a server than you can ever achieve yourself

• CapEx and OpEx

• Capital Expenditure (CapEx): Money invested in assets (E.g., a computer) that return investment over time

• Operational Expenditure (OpEx): Money spent every day on operating expenses

• Consumption-Based Model

• Pay per minute

• Pay per hour
• Pay per execution

Paradigms for hosting applications (IaaS, PaaS, SaaS)

• IaaS (Infrastructure as a Service)

• Virtual machine, networking, load balancer, firewall

• Maximum control over the hardware

• PaaS (Platform as a Service)

• No direct access to the hardware. "Upload the code and the platform will execute and provide it"

• You have to choose an App Service Plan

• Scaling is your responsability

• Serverless

• Even less access to the server than PaaS

• Serverless means not worrying about choosing the right plan
• You pay nothing is you don't use the service

• Functions, Serverless Kubernetes, SQL DB serverless, Cosmos DB serverless

• SaaS (Software as a Service)

• The application is already there. You don't have to deal with code

• Access to configuration only
• Subscription model

• Microsoft 365, Skype, etc

• On-premise

• You buy a machine and manager it yourself

• The Shared Responsability Model tells up to until what task the cloud provider or the customer is responsible for

Cloud implementation models

• Public cloud

• Computing services offered over public internet

• There might be unattended security requisites in the model

• Private cloud

• Computing services offered to only selected users; internal or corporate cloud

• Cloud environment in your own datacenter (E.g., Openstack)

• There will be CapEx to buy the necessary hardware and OpEx for its maintenance

• Hybrid cloud

• Combination of public and private cloud

• Usually the private cloud is used, but when it needs to scale (in a peak), it goes to the public cloud
• E.g., Host a website in public cloud and database in private cloud