ASP.NET Core 7

Mcrosoft.NetCore.App
- the .NET Runtime
Microsoft.AspNetCore.App
- ASP.NET Core

WebApplication Builder

- Services
	- Dependency Container, Provides using IServiceColleciton Contract
		- ServiceDescriptor class
			- Decide an Activation for the Dependency
				- Singleton
				- Scopped
				- Transient
- Configuration
- Socket
- Middlewares
	- Builder for COnfiguring Middlewares in HTTP Pipeline that manages Request and Respons (aka HttpContext)

API COntroller

- ControllerBase
	- BAse class for API Controller
		- Uses ROuting to MAp HTTP Request to HTTP Action Method
			- HTTP GET, POST, PUT, and DELETE

	-  Action Method
			- A Method that will be invoked based on the Http REquest
					- Action Delegate with ExecuteAsync() Method
			- IActionResult INterface Cotractn
	- HTTP Response Methods
		- Ok(), NotFOund(), Conflict(), BadRequest(), etc.
		- File Operations
	- Property System
		- HttpRequest, HttpResponse
		- MOdelState
			- For Model VAlidation
		- ROuteData	
			- USed to Read the Http Route	INformation
				- https://SREVER/api/COntrollerClass/{PARAMETERS}

ApiControllerAttribute class
- use to Read HTTP POST and PUT Request and Map Data from HTTP BOdy to the CLR Object (Entity Object / POCO ) for Write OPerations
HTTP Template CLasses
- HttpGet
- HttpPost
- HttPut
- HttpDelete

Microservice as Technology

Deployment COnfigurtion
- Docker for on Premises
- Kubernetes for Multiple Microservices on Cluster
  - Docker-Desktop
  - Docker Repository
    - Docker Hub
    - Azure COntainer Registry aka ACR
  - Cluster
    - Docker-Desktop, a Single Node Cluster
    - Azure Kubernetes Service aka AKS
- CI/CD Pipeline
DataSTore Strategies
Sharing Data Across Microservices
- Communication Across Microservices
  - Sync
    - HTTP COmminicaton across Microservices
    - BLOCKs the execution
  - Async
    - Pattern for Data Sharing using one of the following
      - RabbitMQ
      - Azure Service Bus
      - Kafka
Resilient Design
- Retry Policies
- Fallback
Discovery with Gateways
Security

Docker

Virtiuaozation Host for the Microservices (not limitted only for them)
Docker Commands
- CLI Commands for Image and Container Management
- Login to the Repository
  - docker login
- Build an Image
  - Navigate to the pathe where 'Dockerfile' exist
  - docker build .-t [IMAGE-NAME]:[TAG]
    - -t is the tag switch
    - IMAGE-NAME, the name of the image always in lower case
    - TAG, the version of the image
  - Running an image in the container
    - docker run -p [PORT-FROM-HOST-MACHINE]:[PORT-EXPOSED-BY-CONTAINER] --nam [CONTAINER-NAME] [IMAGE-NAME]:[TAG]
      - PORT-FROM-HOST-MACHINE, using this port the API Running inside the container canbe accessed
      - PORT-EXPOSED-BY-CONTAINER, mentioned in Dockerfile
      - CONTAINER-NAME, the Unique name in lower case in which the docker image is running
  - Running Container and hence an image in background
    - docker run -it -p [PORT-FROM-HOST-MACHINE]:[PORT-EXPOSED-BY-CONTAINER] --nam [CONTAINER-NAME] [IMAGE-NAME]:[TAG]
  - Running an image in Interactice Mode, we can access the OS prompt of the Conatiner
    - docker run -p [PORT-FROM-HOST-MACHINE]:[PORT-EXPOSED-BY-CONTAINER] --nam [CONTAINER-NAME] [IMAGE-NAME]:[TAG]
  - Process of Removing an Image
    - If an Image is in Use then stop container
      - docker stop [CONTAINER-NAME] | [CONTAINER-ID]
    - Remove the Container
      - docker rm [CONTAINER-NAME] | [CONTAINER-ID]
    - Remove the Image
      - docker rmi [IMAGE-NAME]:[TAG]
  - List all Images
    - docker images
  - LIst all Containers
    - docker ps
  - LIst of all allocated contaiers (Containers in Use)
    - docker ps -a
  - Making docker image ready for deployment
    - Tag the image to the Repository NAme
      - docker tag [IMAGE-NAME]:[TAG] [REPOSITORY-NAME]/[IMAGE-NAME]:[TAG]
    - PUSH the image to the Repository
      - docker push [REPOSITORY-NAME]/[IMAGE-NAME]:[TAG]
    - Pull an image
      - docker pull [REPOSITORY-NAME]/[IMAGE-NAME]:[TAG]
Docker Repository - https://hub.docker.com

DOcker COmpose

Build and Run Multiple Images
- Allocate the Processor
- Allocate memory
- Register Network Resources on-premises
docker-compose.yml file
- uses individual docker files for each service
- BUild IMages
- Allocate Resources
- COnfigure Network
- STart Images by allocating ports
Commands
- docker-compose up
  - load Dockerfile for each service
  - BUild Image
  - If exists any dependencies then those will be resolved
  - ALlocate Network Resources
  - Expose Services on Ports
- docker-compose down

Best Practices while working with Microservices

Database
- MUST be avaialble from the public Endpoint
  - Cloud
- CReate Separate deployable services for Read and Write
  - Command (Write)-Query(Read)-Responsibility-Seggrigation (CQRS)
- ENtityFrameworkCore, the ORM
  - Microsoft.EnttyFrameworkCore
  - Microsoft.EnttyFrameworkCore.SqlServer
  - Microsoft.EnttyFrameworkCore.Relational
  - Microsoft.EnttyFrameworkCore.Design
  - Microsoft.EnttyFrameworkCore.Tools
Publishing Microservice for Production
- Exposing Microservices with Gateway
  - Programatically
    - Create Gateway Explicitly
      - Ocelot
    - Up-time management of Microservices
      - Retry Policies
        
        Resiliancy
      - Circuit Breaker Pattern
  - From the deployment ENv
    - Serverless
- Communication Pattern Across Microservices, DDD
  - Synchronous
    - HTTP COmmuncation across,
  - Async
    - Infra Services
      - RabbitMQ
      - ASB
      - SQS
      - Kafka

Azure Kuerbetes Service

deployment.yaml
- Deployment COnfiguration
  - Image
    - Specify the PORT exposed by the Container
  - Resources
    - CPU
    - Memory
- Service Configuration
  - COmmunication Ports
    - LOadBalancer
    - Mapping between the LoadBalancer and the PORT exposed by the Container
    - Protocal
      - Http / Https
  - IP Address
    - LoadBaancer
      - Public IP
kubectl apply -f deployment.yaml

Ocelot

AddOcelot() Service Method
- A COnfiuration in a memory of app that created a DIctionary of Maping gateway api with actual Services
- gatewayconfiguration.json file
  - ROutes[{ upstream downstream }]
  - Actual Gatewayy Host COnfiguration

Observations

What if the actual MicroServices is down?
- Listening to Exception but so not bubble it
  - Listent and Log the exception Type
- Retry the Call to Microservice in TimeSpan
  - STill Failure then Fallback
- Resiliency for Retry
- Circuit Breaker for Fallback
- Polly
How the Data Can be shared with COnsistency across Services?

maheshsabnis / Spot_Apps

ASP.NET Core 7

WebApplication Builder

API COntroller

Microservice as Technology

Docker

DOcker COmpose

Best Practices while working with Microservices

Azure Kuerbetes Service

Ocelot

Observations

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