maheshsabnis / FunctionMay

Azure Serverless Principal

• Azure Functions
  • Azure Based Serverless Object Model
  • .NET 6 Runtime
    • Use dotnet.exe to load the function code and execute
  • .NET 6, 7 and V4 Isolated Process
    • Use an isolated dedictaed Process to execute the function
• .NET 6 Runtime
  • Mirosoft.NET.Sdk.Functions
    • An object model that has
      • All Triggers
      • Execution
      • Resource Management
        • Dependencies
  • FunctionNameAttribute class
    • The class taht is applied on the method to set behavior to that method as a function method
      • function method, is the method that will be invoked inside the runtime based on Trigger
  • local.settings.json
    • Configuration file for local execution
    • This will contains
      • Connection String to Storage
      • Any other configuration values which we cannot / should not store in code
  • host.json
    • This will nbe usd by Azure DeploymentEnvironment
    • Same as local.settings.json for Azure deployment
• For deploying on Azure follow steps as mentioned below
  • MUST have Azure Subscription
    • https://azure.microsoft.com/en-us/free/
  • Create a resource group
    • A Logical Container (Like Folder) where all the Azure Resources e.g. Storage, VM, API App, Databse etc. are stored
  • We can create an Azure Function using Azure Portla inside the resource group
  • Selecting Deployment Plan for Azure Function
    • Consumption (Serverless)
      • Optimized for serverless and event-driven workloads.
        • CPU, RAM and other resource will be allocated only when the trigger is fired
    • Functions Premium
      • Event based scaling and network isolation, ideal for workloads running continuously.
      • e.g.
        • Process of large Datasets
    • App service plan
      • Fully isolated and dedicated environment suitable for workloads that need large SKUs or need to co-locate Web Apps and Functions.
      • Use Azure function as a Full Implementation of the API Apps
• HttpTriggers
• BLOBTriggers
• Durable Functions
  • Chain
  • FanOut/FanIn
  • Monitor
• Security
• Deplopyment
• Logic Apps
• Availability

Azure Function App Development

1. Configure Data Access Layer
   • ORM

     • Entity Framework Core (EF Core)

       • Install Packages for the Project from dotnet CLI
       • Install EF Global Tool
         • dotnet tool install --global dotnet-ef
       • Install Following Packages
         • dotnet add package Microsoft.EntityFrameworkCore -v 6.0.13
         • dotnet add package Microsoft.EntityFrameworkCore.SqlServer -v 6.0.13
         • dotnet add package Microsoft.EntityFrameworkCore.Relational -v 6.0.13
         • dotnet add package Microsoft.EntityFrameworkCore.Design -v 6.0.13
         • dotnet add package Microsoft.EntityFrameworkCore.Tools -v 6.0.13

     • Generate Model Classes and Data Access using EF Core

       • dotnet ef dbcontext scaffold "DATABASE-CONNECTION-STRING" Microsoft.EntityFrameworkCore.SqlServer -o Models
       • dotnet ef dbcontext scaffold "Data Source=.;Initial Catalog=Company;Integrated Security=SSPI" Microsoft.EntityFrameworkCore.SqlServer -o Models

     • Package for Dependency Container

       • Microsoft.Azure.Functions.Extensions

Function Authorization Level

- Admin
	- aka Master, the Mastre Key is needed to call functions in App
	- This is also known as 'host' key
- Function
	- Each function will have seperate Key
	- We can share seperate key to client to make sure that they can access only function of  which key is available with them
- Anonymous (No recommended)
	- Anybody can directly access function
	- Any Valid HTTP request can access fucntion

Using Azure Storage Services with Functions

- Create an Azure Storage Account
	- The Service That manages Azure Storage Services
		- Table
			- NoSQL Data Store
			- Schema Independant (Free) data store
			- Accessible using TableTrigger
		- BLOB
			- Binary Files Stores
				- Text, Xml, Json, Csv, Images, and Documents
			- Page Blobs
				- Streaming
				- Size if More than 10 GBs
			- BlobkBLOBS
				- File Operations are performed by dividing the BLOB into Chunks 
			- Accessibel using BlobTrigger
		- Queue
			- Messaging
			- Binary Encoded Message
			- 7 Days of Store
			- Accessible using QueueTrigger
		- Files
			- Large Files
			- VHD File
	- Use the Following package to access Queue Storage
		- Azure.Storage.Queues

Azure Durable Functions

- Microsoft.Azure.WebJobs.Extensions.DurableTask
	- OrachestrationTrigger
		- Set an execution Context using IDurableOrchestionContext interface
			- This is responsible for State management across Fucntions
- ActivityTrigger
	- This is the Function that will be executed inside the context when it is invoked by the IDurableOrchestionContext
- Using Fan Out/ Fan In Pattern
	- Use The 'Task' class
		- A Unit of Async Opetration in .NET
		- A Task is a Thread
			- It has decicated operation to execute
			- It has a isolated scope of execution
			- The Start, Wait, WaitAll, etc. method to manages the Task