I'll go over how to construct a.NET MAUI Popup page with Visual Studio 2022 in this tutorial. Operating systems offer a mechanism to display a message and request a response from the user. These alerts are usually restricted in terms of the content a developer can provide as well as the layout and appearance. Popups are a very common way of presenting information to a user that relates to their current task.

Important

• An exception will be raised when attempting to display your Popup if the code underlying the file is not generated concurrently with the call to InitializeComponent.
• Only a Page or an implementation that derives from a Page may display a Popup.

Take note

• It will finish and return to the calling thread before the operating system dismisses the Popup from the screen since Close() is a fire-and-forget procedure. Use CloseAsync() in its place if you need to stop your code from running until the operating system has removed the Popup from the screen.
• The ResultWhenUserTapsOutsideOfPopup property allows you to modify the value that is returned in order to handle tapping outside of a Popup while also waiting for the outcome.
• Make sure to specify the ApplyToDerivedTypes property on the Style definition when establishing a style that targets Popup if you want it to apply to custom popups, such as the SimplePopup example.

Step 1: Open Visual Studio 2022, create a new project, and choose the app option under the multiplatform section on the left side panel. Next, Select the.NET MAUI App with C# option and press the continue button.

Step 2: You must choose the.Net framework version 6.0 and press the proceed button on the following screen.

Step 3: Click the Create button after entering your location, the name of your project, and the name of your solution on the following screen.

Step 4: The NuGet Package CommunityToolkit needs to be downloaded.The MauiProgram.cs file needs to be configured for Maui and CommunityToolkit.
The Community Toolkit can be downloaded using NuGet Package Manager.

dotnet add package CommunityToolkit.Maui --version 7.0.1

2. Configure CommunityToolKit in MauiProgram.cs.
using Microsoft.Extensions.Logging;
using CommunityToolkit.Maui;

namespace Popup
{
    public static class MauiProgram
    {
        public static MauiApp CreateMauiApp()
        {
            var builder = MauiApp.CreateBuilder();

            builder
                .UseMauiApp<App>()
                .UseMauiCommunityToolkit()
                .ConfigureFonts(fonts =>
                {
                    fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                    fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
                });

#if DEBUG
            builder.Logging.AddDebug();
#endif

            return builder.Build();
        }
    }
}

Step 5. The next step is to create the new content page and define the Community Popup view In order to use the toolkit in XAML the following xmlns need to be added to your page or view.
xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"

Therefore, the following
<?xml version="1.0" encoding="utf-8" ?>
<mct:Popup xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
           xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
           xmlns:mct="clr-namespace:CommunityToolkit.Maui.Views;assembly=CommunityToolkit.Maui"
           x:Class="Popup.MainPage"
           CanBeDismissedByTappingOutsideOfPopup="False"
           Size="300, 300">

    <Border VerticalOptions="CenterAndExpand"
            HorizontalOptions="CenterAndExpand"
            Stroke="White"
            StrokeThickness="1"
            StrokeShape="RoundRectangle 10">

        <VerticalStackLayout VerticalOptions="CenterAndExpand" Spacing="20">

            <Label Text="Welcome to .NET MAUI!"
                   VerticalOptions="Center"
                   HorizontalOptions="Center" />

            <Button Text="Close" Clicked="Button_Clicked" />

        </VerticalStackLayout>

    </Border>
</mct:Popup>

Step 6. The next step is to call the Popup from Main Page event or initialization and A Popup can only be displayed from a Page or an implementation inheriting from Page.
using CommunityToolkit.Maui.Views;

namespace Popup
{
    public partial class FirstPage : ContentPage
    {
        public FirstPage()
        {
            InitializeComponent();
        }

        private void OnCounterClicked(object sender, EventArgs e)
        {
            this.ShowPopup(new MainPage());
        }
    }
}

Output screen

With any luck, this post has provided you with enough knowledge to use viewmodel to design an MAUI collection view and execute the application on both iOS and Android. Please feel free to leave a comment if you would like me to go into further detail on anything I've covered in this post.

In modern web development, making HTTP requests is a fundamental aspect of building robust and dynamic applications. In the .NET Core ecosystem, the HttpClient class has long been the go-to choice for sending HTTP requests. However, as applications grow in complexity, managing instances of HttpClient can become a challenge. This is where the HttpClientFactory in .NET Core comes to the rescue, providing a more efficient and scalable solution for handling HTTP requests.

HttpClient: What is it?
Developers can send and receive HTTP requests and responses by using the HttpClient class in the System.Net.Http namespace. Because of its portability and ability to establish and manage HTTP connections, it can be used in situations where several requests are sent to the same endpoint.

This is a simple example of sending a GET request using HttpClient.

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        using (HttpClient client = new HttpClient())
        {
            string url = "https://api.example.com/data";
            HttpResponseMessage response = await client.GetAsync(url);

            if (response.IsSuccessStatusCode)
            {
                string result = await response.Content.ReadAsStringAsync();
                Console.WriteLine(result);
            }
        }
    }
}

Even if this method functions, it's not the most effective for handling several requests at once. It is typically not advised to create a new instance of HttpClient for each request as this can cause problems such as socket exhaustion.

HttpClientFactory: What is it?
The HttpClientFactory is part of the Microsoft.Extensions.In order to overcome the problems of manually managing HttpClient instances, the http package was established. It offers a more organized and scalable method for setting up, configuring, and administering HttpClient instances.

Principal Advantages of Using HttpClientFactory

• Lifetime Management: It manages the HttpClient instances' lifecycle, reusing existing connections to avoid problems like socket exhaustion.
• Configuration: HttpClientFactory makes it easier to manage many API endpoints with distinct settings by enabling you to configure HttpClient objects through named clients.
• Dependency Injection Integration: It makes injecting HttpClient objects into your services simple by integrating smoothly with the ASP.NET Core dependency injection framework.

HttpClientFactory use
Let's begin by going over how to use HttpClientFactory in a.NET Core application step-by-step.
1. Set up the required NuGet package.
dotnet add package Microsoft.Extensions.Http

2. Configure HttpClient in Startup.cs
services.AddHttpClient("MyApiClient", client =>
{
    client.BaseAddress = new Uri("https://api.example.com/");
    // Additional configuration options can be set here
});

3. Inject HttpClient into your service
public class MyService
{
    private readonly HttpClient _httpClient;

    public MyService(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    // Use _httpClient to make requests
}

4. Use IHttpClientFactory for manual creation (optional)
If you need more control, you can inject IHttpClientFactory and create HttpClient instances manually.
public class MyService
{
    private readonly IHttpClientFactory _httpClientFactory;

    public MyService(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;
    }

    public async Task MakeRequest()
    {
        HttpClient client = _httpClientFactory.CreateClient("MyApiClient");
        HttpResponseMessage response = await client.GetAsync("/data");
        // Handle the response
    }
}

In order to effectively use HttpClient and fully utilize HttpClientFactory, one must grasp HTTP requests in.NET Core. By implementing best practices, developers may create scalable and performant apps that communicate with external APIs with ease. Examples of these practices include controlling the lifetime of HttpClient objects and utilizing dependency injection. Developers may design dependable, high-performance solutions for managing HTTP requests in their.NET Core applications with the help of HttpClient and HttpClientFactory.

Overview of the Entity Framework
A strong and adaptable Object-Relational Mapping (ORM) framework that makes database interactions in.NET applications easier is called Entity Framework (EF). We'll explore several Entity Framework techniques in this extensive tutorial, with examples to help even.NET novices understand the ideas.

Entity Framework removes the requirement for developers to write raw SQL queries by enabling them to communicate with databases using.NET objects. It supports various strategies, each having benefits and applications of its own.

1. A database-first strategy
The Database-First method entails building the database first, then using it to generate the model.
Actions

• Build Database: Using SQL Server Management Studio or another database tool, design and build the database.
• Create Model: To create the model from the current database, use the Entity Data Model Wizard.
• Employ Created Classes For database activities, make use of the automatically produced classes.

// Auto-generated class representing a table in the database
public partial class Product
{
    public int ProductID { get; set; }
    public string ProductName { get; set; }
    // Other properties
}

// Usage in code
using (var context = new YourDbContext())
{
    var products = context.Products.ToList();
    // Perform operations on products
}

2. Code-First Approach
The Code-First method starts with the creation of the domain classes, from which the database is then generated.
Actions

• Establish domain classes that represent entities by using define classes.
• Establish Relationships: To establish relationships between entities, use Data Annotations or Fluent API.
• Create Database: Based on the model, create and update the database using migrations.

public class Product
{
    public int ProductID { get; set; }
    public string ProductName { get; set; }
    // Other properties
}

public class YourDbContext : DbContext
{
    public DbSet<Product> Products { get; set; }
    // Other DbSets

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // Fluent API configuration for relationships
    }
}

3. Model-First Method
Using the Entity Data Model Designer, the Entity Data Model (EDM) is created, and the database is subsequently generated from it via the Model-First approach.
Actions

• To develop an Entity Data Model, use the Entity Data Model Designer.
• Generate Database: Select the Generate Database from Model option to generate the database from the EDM.

As an illustration
With Entity Data Model Designer, the model-first approach frequently incorporates visual design, which makes it less code-oriented.

4. Context of Databases and LINQ Queries
Whichever strategy is used, after the model is created developers use a database context to communicate with the database via LINQ queries.

using (var context = new YourDbContext())
{
    var products = from p in context.Products
                   where p.ProductName.Contains("Shoes")
                   select p;

    // Perform operations on products
}

Comprehending the various methodologies in Entity Framework enables.NET developers to select the most appropriate technique for their project needs. Entity Framework offers flexibility and abstraction for effective database interactions in.NET applications, regardless of your preference for building databases first, writing classes, or using visual modeling.

Have fun with coding!

To start a new ASP.NET Core Web API project, use the command line or Visual Studio.
dotnet new webapi -n WorkingwithSQLLiteinAsp.NETCoreWebAPI
cd WorkingwithSQLLiteinAsp.NETCoreWebAPI

Install SQLite NuGet Package
Install the SQLite NuGet package to enable SQLite support in your project.
dotnet add package Microsoft.EntityFrameworkCore.Sqlite

Now Create SQLite Database File in your Project
SQLLiteDatabase.db

Create Model
namespace WorkingwithSQLLiteinAsp.NETCoreWebAPI.Models
{
    // Models/TodoItem.cs
    public class TodoItem
    {
        public long Id { get; set; }
        public string Name { get; set; }
        public bool IsComplete { get; set; }
    }

}

Now Crete Application Database Context
using Microsoft.EntityFrameworkCore;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.Models;

namespace WorkingwithSQLLiteinAsp.NETCoreWebAPI.ApplicationDbContext
{
    public class AppDbContext : DbContext
    {
        public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }

        public DbSet<TodoItem> TodoItems { get; set; }
    }
}

Add Connection string in AppSetting.JSON File
// appsettings.json
{
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=SQLLiteDatabase.db"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

Register the Dependancy in Program.cs File
using Microsoft.EntityFrameworkCore;
using Microsoft.OpenApi.Models;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.ApplicationDbContext;

var builder = WebApplication.CreateBuilder(args);
var configuration = builder.Configuration;

// Add services to the container.
builder.Services.AddDbContext<AppDbContext>(options =>
        options.UseSqlite(configuration.GetConnectionString("DefaultConnection")));
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo { Title = "Working with SQLLite In Asp.net Core Web API", Version = "v1" });

});

var app = builder.Build();

// Configure the HTTP request pipeline.
if(app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();

Create and Apply Migrations
Run the following commands to create and apply migrations to create the SQLite database.
dotnet ef migrations add InitialCreate
dotnet ef database update

CRUD Operations
Implement CRUD operations in your controller.
// Controllers/TodoController.cs
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.ApplicationDbContext;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.Models;

[ApiController]
[Route("api/[controller]/[Action]")]
public class TodoController : ControllerBase
{
    private readonly AppDbContext _context;

    public TodoController(AppDbContext context)
    {
        _context = context;
    }

    // GET: api/Todo
    [HttpGet]
    public async Task<ActionResult<IEnumerable<TodoItem>>> GetTodoItems()
    {
        return await _context.TodoItems.ToListAsync();
    }

    // GET: api/Todo/5
    [HttpGet("{id}")]
    public async Task<ActionResult<TodoItem>> GetTodoItem(long id)
    {
        var todoItem = await _context.TodoItems.FindAsync(id);

        if(todoItem == null)
        {
            return NotFound();
        }

        return todoItem;
    }

    // POST: api/Todo
    [HttpPost]
    public async Task<ActionResult<TodoItem>> PostTodoItem(TodoItem todoItem)
    {
        _context.TodoItems.Add(todoItem);
        await _context.SaveChangesAsync();

        return CreatedAtAction(nameof(GetTodoItem), new { id = todoItem.Id }, todoItem);
    }

    // PUT: api/Todo/5
    [HttpPut("{id}")]
    public async Task<IActionResult> PutTodoItem(long id, TodoItem todoItem)
    {
        if(id != todoItem.Id)
        {
            return BadRequest();
        }

        _context.Entry(todoItem).State = EntityState.Modified;

        try
        {
            await _context.SaveChangesAsync();
        }
        catch(DbUpdateConcurrencyException)
        {
            if(!TodoItemExists(id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return NoContent();
    }

    // DELETE: api/Todo/5
    [HttpDelete("{id}")]
    public async Task<IActionResult> DeleteTodoItem(long id)
    {
        var todoItem = await _context.TodoItems.FindAsync(id);
        if(todoItem == null)
        {
            return NotFound();
        }

        _context.TodoItems.Remove(todoItem);
        await _context.SaveChangesAsync();

        return NoContent();
    }

    private bool TodoItemExists(long id)
    {
        return _context.TodoItems.Any(e => e.Id == id);
    }
}

Output

Conclusion
SQLite is a relational database management system (RDBMS) that is self-contained, serverless, and requires no configuration. It is an embedded database engine that is lightweight, open-source, and runs directly on the client device, eliminating the need for a separate server process. Some of SQLite's key features are.

• Self-contained: It is simple to install and maintain because the whole database system is housed in a single library.
• Serverless: SQLite does not function as a separate server process, in contrast to conventional database management systems. Rather, it is incorporated straight into the program.
• Zero-configuration: Complex setup or administration are not necessary for SQLite. The database is a single, straightforward file that often has a.db extension; no server setup or upkeep is required.
• Cross-platform: SQLite is compatible with a number of operating systems and mobile platforms, including iOS and Android, as well as Windows, macOS, and Linux.
• Single-user: Because SQLite is optimized for single-user applications, embedded systems, mobile apps, and lightweight desktop programs can all benefit from its use.
• ACID-compliant: SQLite preserves the ACID (Atomicity, Consistency, Isolation, Durability) qualities, guaranteeing data reliability and integrity, even with its lightweight design.
• Dynamic typing: SQLite stores data using dynamic typing, which enables users to store several kinds of data in the same column.
• Broad language support: SQLite is adaptable to a variety of development contexts since it supports a wide range of programming languages, including C, C++, Java, Python, and.NET.

SQLite is often utilized in situations where a lightweight and integrated database solution is needed, such as mobile applications, desktop software, and embedded systems, because of its simplicity, portability, and ease of integration.

FluentValidation: What Is It?
An open-source validation toolkit for.NET called FluentValidation offers a fluid interface for creating and implementing validation rules. It makes validation logic easy to comprehend, write, and maintain by enabling developers to describe it succinctly and clearly.

.NET 8's FluentValidation
Installing the FluentValidation NuGet package is required in order to use FluentValidation in.NET 8. The following command can be used to accomplish this in the.NET CLI or Package Manager Console:

dotnet add package FluentValidation

Verifying a Basic User Model
Let's construct a straightforward example in which we wish to validate a User class. To make sure the user's email address is legitimate and their name is not empty, we will use FluentValidation.

using FluentValidation;

public class User
{
    public string Name { get; set; }
    public string Email { get; set; }
}

public class UserValidator : AbstractValidator<User>
{
    public UserValidator()
    {
        RuleFor(user => user.Name).NotEmpty().WithMessage("Name cannot be empty");
        RuleFor(user => user.Email).NotEmpty().EmailAddress().WithMessage("Invalid email address");
    }
}

In this instance:

• We provide properties for Name and Email in our User class definition.
• We construct a class called UserValidator, which is derived from AbstractValidator<User>.
• We define validation rules for the Name and Email properties inside the UserValidator constructor using the RuleFor method.

Applying FluentValidation to Your Software
Let's look at how we can utilize FluentValidation in our application now that we have our User class and matching validator:

class Program
{
    static void Main()
    {
        var user = new User { Name = "Mahesh Chand", Email = "[email protected]" };
        var validator = new UserValidator();

        var validationResult = validator.Validate(user);

        if (validationResult.IsValid)
        {
            Console.WriteLine("User is valid");
        }
        else
        {
            foreach (var error in validationResult.Errors)
            {
                Console.WriteLine($"Validation Error: {error.ErrorMessage}");
            }
        }
    }
}

In this instance:

• We construct an instance of the User class and set its properties.
• We instantiate a UserValidator object.
• By handing in the User instance, we invoke the Validate method on the validator.
• We verify the validity of the validation result. We print a success message if it is. If not, we repeat the mistakes and print them.

.NET 8's FluentValidation offers a tidy and expressive approach to handling validation in your applications. You can confidently design and run validation rules thanks to its fluid interface and simple syntax. Using FluentValidation makes it possible to isolate your validation logic apart from your business logic, as seen in our example, which makes your codebase easier to read and manage.

Cross-Origin Resource Sharing (CORS) is a vital security feature that controls how resources on a web page can be accessed by web applications from different domains. In an ASP.NET Core project, enabling CORS involves configuring the server to allow or restrict access to its resources from different origins. Here's a step-by-step guide on establishing CORS in your ASP.NET Core application.

Step 1. Set up the middleware for CORS

Installing the Microsoft.AspNetCore.Cors package is the first step. Using the NuGet Package Manager Console, you may accomplish this.

Install-Package Microsoft.AspNetCore.Cors

Alternatively, you can add it to your project's .csproj file:
<PackageReference Include="Microsoft.AspNetCore.Cors" Version="x.x.x" />

Replace x.x.x with the latest version available.

Step 2. Configure CORS in Startup.cs
Open your Startup.cs file and locate the ConfigureServices method. Add the CORS service by calling AddCors in the ConfigureServices method.
public void ConfigureServices(IServiceCollection services)
{
    // Other configurations

    services.AddCors(options =>
    {
        options.AddPolicy("AllowSpecificOrigin",
            builder =>
            {
                builder.WithOrigins("https://example.com")
                       .AllowAnyHeader()
                       .AllowAnyMethod();
            });
    });

    // Other configurations
}

In the code snippet above:

• The CORS services are added to the application's service container via AddCors.
• AddPolicy generates a specified CORS policy that identifies permitted origins, headers, and methods ("AllowSpecificOrigin" in this example).

To designate which domains are permitted to access your resources, modify WithOrigins. To accept requests from any origin, use a "*".

Step 3. Turn on the CORS middleware
Add the CORS middleware to Startup.cs's Configure function.

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // Other configurations

    app.UseCors("AllowSpecificOrigin");

    // Other configurations
}

This middleware must be added before other middleware that may handle requests, such as MVC or static file middleware.

Step 4: Verify Your CORS Setup
Once set up, make queries to your ASP.NET Core APIs from various origins to test the CORS settings. Make that the methods, headers, and permitted origins meet the needs of your application.

In summary
For secure communication between your application and clients from different domains, and to control access to your resources, you must implement CORS in your ASP.NET Core project. You can increase the security of your application while enabling critical cross-origin communication by defining CORS policies, which allow you to control which origins can access your APIs.

Always keep in mind to properly set your CORS policies based on the security requirements of your application, keeping in mind the possible hazards related to cross-origin requests.

One of the most frequent problems that developers encounter in the intricate and ever-changing process of software creation is the "class explosion." This happens when a software system has a lot of classes—often more than what was planned or organized in the first place. We will examine the reasons behind the class explosion, how it affects software systems, and management and mitigation techniques in this post.

Reasons for the Explosion of Classes
Excessively Fine-Grained Design: An excessively fine-grained design is one of the main reasons for class explosion. The number of classes can grow rapidly when every task or feature is included within a distinct class without a clear and obvious goal in mind.

class UserManager { }

Inadequate Abstraction: An excessive number of classes may result from improper abstraction. Class fragmentation occurs when developers are unable to recognize and produce meaningful abstractions, leading to an abundance of tiny, specialized classes.

class User { }
class UserValidationHelper { }
class UserPersistenceManager { }

Insufficient Planning: In some cases, inadequate upfront planning can contribute to class explosion. If the design lacks a clear structure and roadmap, developers might introduce new classes in a reactionary manner, leading to an unmanageable number of classes.

class FeatureAProcessor { }
class FeatureBProcessor { }
class FeatureCProcessor { }

The effects of the class explosion

• Complexity and Cognitive Load: The system's total complexity rises with the number of classes. The relationships and responsibilities of each class may be difficult for developers to understand, which will raise their cognitive load.
• Maintenance Challenges: Having a lot of classes may make maintenance difficult. It becomes more difficult to make modifications or add new features since developers have to work their way through a complex class hierarchy.
• Decreased Reusability: Decreased reusability may result from an excessive number of classes. It's possible that developers will have to start from scratch if they try to utilize tiny, specialized classes in other areas of the system.

Techniques to Control Class Explosion
Refactoring: Examine and reorganize the codebase on a regular basis to find and remove superfluous classes. Combine features into classes that are well-thought-out and integrated.

class UserManager { }

Abstraction and Encapsulation: Emphasize proper abstraction and encapsulation to ensure that classes have well-defined responsibilities. Avoid creating classes for every minor task and focus on creating meaningful, high-level abstractions.
    class User { }
    class UserManager { }

​​​Design Patterns: Utilize design patterns to manage class complexity. Patterns like the Singleton pattern, Factory pattern, and Strategy pattern can help organize and streamline class hierarchies.

class UserFactory { }

Modularization: Modularize the system into manageable modules or components. Divide the system into cohesive parts, each with a distinct responsibility, to prevent the proliferation of classes.
class AuthenticationModule { }

Guidelines and Code Reviews: Establish coding guidelines and conduct regular code reviews to ensure that the development team adheres to best practices. Enforce consistency in class design and encourage developers to think about the overall system architecture.

Example: Refactoring a Class Explosion
Consider a scenario where a class explosion has occurred in a system responsible for handling various geometric shapes:

class SquareValidator { }
class SquareCalculator { }
class CircleValidator { }
class CircleCalculator { }
class TriangleValidator { }
class TriangleCalculator { }

There are numerous classes as a result of this design's lack of abstraction. Let's rework this situation by adding an abstract and more unified design:

abstract class Shape { }
class Square extends Shape { }
class Circle extends Shape { }
class Triangle extends Shape { }

class ShapeValidator { }
class ShapeCalculator { }

We've added an abstract Shape class as part of this refactoring, which eliminates duplication and creates a more organized and manageable design.

In summary
Although class explosion is a typical problem in software design, it may be controlled and lessened with careful planning, frequent refactoring, and strict code standards. Developers can design systems that are not only scalable but also easier to understand and manage over time by placing a strong emphasis on appropriate abstraction, encapsulation, and modularization. Recall that a well-designed system prioritizes the classes' meaningful order and coherence over their quantity.

REST API: What is it?
REpresentational State Transfer is what the acronym REST stands for. It's an architectural design that lays forth a set of guidelines for building Web services. REST recommends generating an object from the data a client requests and responding to the user with the object's values via a client-server conversation. For instance, you can construct an object on the server-side if the user requests a Bangalore taxi reservation at a specific location and time. You have an object over here, and you are transmitting the object's state. As a result, Representational State Transfer, or REST, is its name.

An application can be made more appropriate for the internet by utilizing the reduced bandwidth usage provided by the REST architectural style. It is entirely dependent on the resources and is frequently referred to as the "language of the internet."

REST API Fundamentals
The six REST guiding principles are listed below:

Without a state

The body of the request contains the current status of the resource, and the URL is used to identify the resource specifically. The client receives a response from the server via headers, body, or status once the request has been processed. All the necessary information is included in the requests that clients send to servers so that the servers can comprehend the requests. This may appear in the body, headers, query-string arguments, or even the URL. The server API does not cache any state, thus each request is independent of the others. Additionally helpful in scaling the API service in a cloud context is its RESTful characteristic.

Client-Server
The client-server architecture enables a uniform interface and separates clients from the servers. This enhances the portability across multiple platforms as well as the scalability of the server components.

Uniform Interface
To obtain the uniformity throughout the application, REST has the following four interface constraints:

• Resource identification
• Resource Manipulation using representations
• Self-descriptive messages
• Hypermedia as the engine of application state

Cacheable
To provide a better performance, the applications are often made cacheable. This is done by labeling the response from the server as cacheable or non-cacheable either implicitly or explicitly. If the response is denied as cacheable, then the client cache can reuse the response data for equivalent responses in the future.
Minimal APIs in .Net 8 or .Net 7

Minimal APIs are architected to create HTTP APIs with minimal dependencies. They are ideal for microservices and apps that want to include only the minimum files, features, and dependencies in ASP.NET Core.

Limitations of Minimal API

• No support for filters: For example, no support for IAsyncAuthorizationFilter, IAsyncActionFilter, IAsyncExceptionFilter, IAsyncResultFilter, and IAsyncResourceFilter.
• No support for model binding, i.e. IModelBinderProvider, IModelBinder. Support can be added with a custom binding shim.
• No support for binding from forms. This includes binding IFormFile. We plan to add support for IFormFile in the future.
• No built-in support for validation, i.e. IModelValidator
• No support for application parts or the application model. There's no way to apply or build your own conventions.
• No built-in view rendering support. We recommend using Razor Pages for rendering views.
• No support for JsonPatch
• No support for OData
• No support for ApiVersioning. See this issue for more details.

With the following APIs,

REST APIs follow standard HTTP Verbs like GET, POST, PUT, DELETE, PATCH which are basically CRUD operation on an object. The APIs are arranged to form an internet resource. For example in the above example, we have resource as “todoitem” which can be created, modified, deleted using APIs, and URL format is formed accordingly.

using Microsoft.EntityFrameworkCore;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddDbContext < TodoDb > (opt => opt.UseInMemoryDatabase("TodoList"));
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment()) {
    app.UseSwagger();
    app.UseSwaggerUI();
}
app.MapGet("/", () => "Hello World!");
app.MapGet("/todoitems", async (TodoDb db) => await db.Todos.ToListAsync());
app.MapGet("/todoitems/complete", async (TodoDb db) => await db.Todos.Where(t => t.IsComplete).ToListAsync());
app.MapGet("/todoitems/{id}", async (int id, TodoDb db) => await db.Todos.FindAsync(id)
    is Todo todo ? Results.Ok(todo) : Results.NotFound());
app.MapPost("/todoitems", async (Todo todo, TodoDb db) => {
    db.Todos.Add(todo);
    await db.SaveChangesAsync();
    return Results.Created($ "/todoitems/{todo.Id}", todo);
});
app.MapPut("/todoitems/{id}", async (int id, Todo inputTodo, TodoDb db) => {
    var todo = await db.Todos.FindAsync(id);
    if (todo is null) return Results.NotFound();
    todo.Name = inputTodo.Name;
    todo.IsComplete = inputTodo.IsComplete;
    await db.SaveChangesAsync();
    return Results.NoContent();
});
app.MapDelete("/todoitems/{id}", async (int id, TodoDb db) => {
    if (await db.Todos.FindAsync(id) is Todo todo) {
        db.Todos.Remove(todo);
        await db.SaveChangesAsync();
        return Results.Ok(todo);
    }
    return Results.NotFound();
});
app.Run();
class Todo {
    public int Id {
        get;
        set;
    }
    public string ? Name {
        get;
        set;
    }
    public bool IsComplete {
        get;
        set;
    }
}
class TodoDb: DbContext {
    public TodoDb(DbContextOptions < TodoDb > options): base(options) {}
    public DbSet < Todo > Todos => Set < Todo > ();
}

In summary
The REST architecture style offers a common method for clients to access and retrieve server data as well as a standard approach to arrange resources across the internet. Minimal APIs need to have the least amount of code possible and can be quickly and simply created without the need for authentication or with very little dependencies by sitting behind a gateway that does.

Logging: What Is It?
The technique of recording events in real time and adding details like execution time and infrastructure information is known as logging in software. It is essential to every software program, especially when debugging problems. Logs are useful for deciphering errors, locating performance snags, and assisting in issue solving.

Logs are commonly kept in files, databases, or consoles according to the convenience and severity of the application. Although logs can contain a variety of data, error and informational messages are frequently recorded. Informational messages record routine activities such as method calls, user logins, or product checkouts, whereas error messages offer detailed information for troubleshooting.

By offering a generic logging interface that is uniform throughout the framework and external libraries, ASP.NET Core streamlines logging. Problem diagnosis and log navigation are made easier by this standardization. Users can set log verbosity and route logs to various locations, including files, consoles, and databases, using the framework.

Logs are stored by logging providers in ASP.NET Core, and users can set up several providers for their apps. Logging providers like Console, Debug, EventSource, and EventLog (unique to Windows) are part of the standard ASP.NET Core configuration.

Recognizing the Difference: Software System Logging vs. Monitoring

ASP.NET Core has helpful tools for logging—a process of recording events in your applications. System events, user actions, performance indicators, and other events and processes are all recorded in detail through logging. This data, which is commonly kept in a database or log file, enables you to see problems and resolve them, enhance performance, and comprehend how your program is utilized.

Contrarily, monitoring entails keeping an eye on and gauging the performance of your application in real time. When specific criteria are met, such as when the program takes too long to react or experiences an error, it can send warnings or notifications. Monitoring offers important insights for performance optimization and assists in identifying and resolving issues before they affect users.

There are well-known tools in ASP.NET Core, such as Microsoft.Extensions.Helping with logging include Serilog, NLog, and logging. These tools assist you in maintaining a robust and effective software system by making it simpler to handle and analyze the data that your application generates.

Additional Information
Logging in.NET Core allows you to monitor activity within your application. It aids in behavior monitoring, problem solving, and performance analysis. Logging is made organized and efficient with the help of the ILogger API. You can store logs in several locations using different logging providers; built-in and third-party choices are available.

Let's now discuss the distinctions between tracing and logging. The goal of logging is to capture important events in your program and produce a sort of summary. However, tracing goes beyond by providing you with an in-depth overview of all the actions taking place within your application, providing a comprehensive history of its operations.

The six main logging levels in .NET

• Critical: This is for really serious issues that could make your app stop working, like running out of memory or space on the disk.
• Error: Use this when something goes wrong, like a database error preventing data from being saved. The app can still work for other things despite encountering errors.
• Warning: Not as severe as errors, but it indicates a potential problem that might lead to more serious errors. It's a heads-up for administrators.
• Information: Gives details about what's happening in the app. Helpful for understanding the steps leading to an error.
• Debug: Useful during development for tracking detailed information. It's not typically used in a live/production environment.
• Trace: Similar to Debug but may include sensitive info. Rarely used and not utilized by framework libraries.

Implement the External Logging Source to Logging Information of API  and Windows Service - Serilog

Packages need: Serilog.AspNetCore

• Dot Net CLI - dotnet add package Serilog.AspNetCore --version 8.0.0
• Package Manager - Install-Package Serilog.AspNetCore -Version 8.0.0

Confiuration of Serilog in API
Settings File

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "Serilog": {
    "Using": [ "Serilog.Sinks.File" ],
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Warning",
        "System": "Warning"
      }
    },
    "WriteTo": [
      {
        "Name": "File",
        "Args": {
          "path": "C:/Log001/log_.log",
          "rollOnFileSizeLimit": true,
          "rollingInterval": "Day"
        }
      }
    ]
  }
}

Application Startup updates for Logging
using Serilog;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

/// Step 1
builder.Host.UseSerilog((context, configuration) =>
{
    configuration.ReadFrom.Configuration(context.Configuration);
}
);

var app = builder.Build();


/// Step 2
app.UseSerilogRequestLogging();

app.Run();

Using the setup to Log actions.
In this setup, we employ the "Assembly - Microsoft.Extensions.Logging.Abstractions, Version=8.0.0.0" for logging actions, and we utilize Serilog to write these logs into files. The ILogger interface is injected into the constructor to facilitate logging functionality.
private readonly ILogger<WeatherForecastController> _logger;

public WeatherForecastController(ILogger<WeatherForecastController> logger)
{
    _logger = logger;
}

[HttpGet(Name = "GetWeatherForecast")]
public IEnumerable<WeatherForecast> Get()
{
    _logger.LogInformation("Method Entered");

    var list = Enumerable.Range(1, 5).Select(index => new WeatherForecast
    {
        Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
        TemperatureC = Random.Shared.Next(-20, 55),
        Summary = Summaries[Random.Shared.Next(Summaries.Length)]
    })
    .ToArray();

    string message = $"WeatherForecast Count {list.Length}";

    _logger.LogInformation(message);

    _logger.LogInformation("Method Exit");
    return list;
}

Now, to test the logging functionality, run the application and inspect the specified path. Refer to the image below for guidance.

Application Startup updates for Logging
using Serilog;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

/// Step 1
builder.Host.UseSerilog((context, configuration) =>
{
    configuration.ReadFrom.Configuration(context.Configuration);
}
);

var app = builder.Build();


/// Step 2
app.UseSerilogRequestLogging();

app.Run();

Using the setup to Log actions.

In this setup, we employ the "Assembly - Microsoft.Extensions.Logging.Abstractions, Version=8.0.0.0" for logging actions, and we utilize Serilog to write these logs into files. The ILogger interface is injected into the constructor to facilitate logging functionality.
private readonly ILogger<WeatherForecastController> _logger;

public WeatherForecastController(ILogger<WeatherForecastController> logger)
{
    _logger = logger;
}

[HttpGet(Name = "GetWeatherForecast")]
public IEnumerable<WeatherForecast> Get()
{
    _logger.LogInformation("Method Entered");

    var list = Enumerable.Range(1, 5).Select(index => new WeatherForecast
    {
        Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
        TemperatureC = Random.Shared.Next(-20, 55),
        Summary = Summaries[Random.Shared.Next(Summaries.Length)]
    })
    .ToArray();

    string message = $"WeatherForecast Count {list.Length}";

    _logger.LogInformation(message);

    _logger.LogInformation("Method Exit");
    return list;
}

Now, to test the logging functionality, run the application and inspect the specified path. Refer to the image below for guidance.

We will learn how to construct and configure the splash screen in.NET MAUI in this tutorial. If you are new to.NET MAUI, I recommend that you read the articles in this series listed below. When you launch the program, a splash screen appears till the application initialization procedure is complete. The Splash screen is removed once the application is ready for usage.

Let's start by making a new.NET MAUI project to learn how to design or edit the Splash Screen. I've started a new project called SplashScreenExample.

When you run the program on an Android device, you will see the default Splash Screen, as shown in the image below.

A splash screen in.NET MAUI can be provided in a single location within the application. In the "ResourcesSplash folder," you will find a scalable vector graphic, splash.svg, with a build action of MauiSplashScreen in the settings box.

Scalable vector graphics have the advantage of being able to be adjusted to the suitable resolution for the target application. Let's swap out the splash screen icon for something new. I already have a medical icon that I will display on the Splash Screen. I removed the splash.svg icon and replaced it with the medical.svg image, with the build action MauiSplashScreen. Make sure the name of the icon you're adding to the Splash screen is lowercase, begins and finishes with a letter character, and only contains alphanumeric characters or underscore.

Now edit the .csproj file of the project as shown in the below image.

Add the BaseSize of a splash screen, which represents the image's baseline density. If no base size is supplied for the vector picture, the dimensions specified in the image are utilized as the base size. BaseSize is supplied using the BaseSize="W,H" syntax, where W is the image's width and H is its height. The BaseSize value supplied must be divisible by 8. In my case, BaseSize="128,128" is divisible by 8.

Use the TintColor property to modify the color of the SVG icon, and the Color property to adjust the backdrop color.

<!-- Images -->
<MauiSplashScreen Include="Resources\Splash\medical.svg" BaseSize="128,128" Color="#F5F7F8" TintColor="#BE3144"/>

Let's create and execute the app in the Android emulator now. You will notice that the Splash Screen with the medical.svg icon is displayed as per the MauiSplashScreen setup.