I begin to learn ASP.NET Core, there, within the framework of the Web API template, there is a Startup class with ConfigureServices() and Configure() methods.

Can anyone tell me about how to use them? I am watching an Udemy course and I didn't understand why the instructor doing

public class Startup
{
    private readonly IConfiguration config;

    public Startup(IConfiguration config)
    {
        this.config = config;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddApplicationServices(this.config);
        services.AddControllers();
        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new OpenApiInfo { Title = "WebAPIv5", Version = "v1" });
        });
        services.AddCors();
        services.AddIdentityServices(this.config);

    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        //if (env.IsDevelopment())
        //{
        //    app.UseDeveloperExceptionPage();
        //    app.UseSwagger();
        //    app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "WebAPIv5 v1"));
        //}
        app.UseMiddleware<ExceptionMiddleware>();

        app.UseHttpsRedirection();

        app.UseRouting();

        app.UseCors(x => x
                   .AllowAnyMethod()
                   .AllowAnyHeader()
                   .SetIsOriginAllowed(origin => true) // allow any origin
                   .AllowCredentials());

CodePudding user response：

services.Add is to register service , app.Use is the way to use Middleware

Configure Service(): It is used to add services to the container and configure those services. basically, service is a component that is intended for common consumption in the application. There is framework service like MVC, EF core, identity so on. but there are also application services that are application-specific like send mail services.

Configure(): it is used to specify how the asp.net core application will respond to individual requests. Through this, we actually build the HTTP request pipeline

public class Startup {
        
        // This method gets called by the runtime. 
          // Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services) {
            // Register services here through dependency injection
        }
  
        // This method gets called by the runtime. 
          // Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, 
                              IWebHostEnvironment env) {
            
            // Add middlware components here
            if (env.IsDevelopment()) {
                app.UseDeveloperExceptionPage();
            }
            app.UseRouting();
            app.UseEndpoints(endpoints => {
                endpoints.MapGet("/",async Context => {
                    await context.Response.WriteAsync("Hello World!");
                });
            });
        }
    }

Read this example to know more.