NETCORE combined with cap event bus to realize distributed transaction -- Introduction (1)

One 、 introduction

1. CAP It's a EventBus, At the same time, it is also a micro service or SOA A framework for solving distributed transaction problems in system . It helps create extensible , A reliable and easy to change microservice system .

2. In Microsoft eShopOnContainer In the microservice example project , Recommended CAP Available as a production environment EventBus.

The event bus is a mechanism , It allows different components to communicate with each other without understanding each other . Components can send events to Eventbus, You don't need to know who answers or how many others answer . Components can also listen Eventbus Events on the , Without knowing who sent the event . such , Components can communicate with each other without interdependency . Again , It's easy to replace a component . As long as the new component knows what events are being sent and received , Other components will never know .

Compared with other Service Bus perhaps Event Bus, CAP Have their own characteristics , It does not require the user to implement or inherit any interface when sending or processing messages , It has very high flexibility . We have always believed that convention is more important than configuration , therefore CAP It's very simple to use , Very friendly for beginners , And it has lightweight .

Two 、 Environment building

1. install nuget

Install-Package DotNetCore.CAP

2. install RabbitMq
   Download from the official website
   （ Reprint ）RabbitMq Detailed explanation

3、 ... and 、 Configuration information

Publisher

1. Startup.cs

ConfigureServices Method 


services.AddCap(x =>
            {
    
                //  If your  SqlServer  The use of  EF  Data manipulation , You need to add the following configuration ：
                //  Be careful :  You don't have to configure it again  x.UseSqlServer(""")
                x.UseEntityFramework<PubDBContext>();
                // To configure RabbitMq Information 
                x.UseRabbitMQ(rb =>
                {
    
                //RabbitMq Address of the server 
                    rb.HostName = "localhost";
                    // Set the user name （ The default generation is guest user , The password is guest,
                    // This is where I am Mq Added in admin user , Password setting admin）
                    rb.UserName = "admin";
                    // Set the password 
                    rb.Password = "admin";
                    // Default port 
                    rb.Port = 5672;
                    // A virtual host can have several Exchange and Queue, The same virtual host cannot have the same name Exchange or Queue.
                    // Virtualize a host into multiple , Similar to routing 
                    rb.VirtualHost = "Angel2022";
                    // Switch name used 
                    rb.ExchangeName = "AngelCapExchange";
                    // Set the message expiration time 
                    rb.QueueMessageExpires = 24 * 3600 * 10;
                });
            }

// add to  PubDBContext efCoreApp
       public void Configure(IApplicationBuilder app, IWebHostEnvironment env, PubDBContext efCoreApp)
        {
    
        	efCoreApp.Database.EnsureCreated();
        }

2.PubDbContext

appsettings.json File configuration connection string

using Microsoft.EntityFrameworkCore;

namespace _01_Publisher
{
    
    public class PubDBContext : DbContext
    {
       
        public PubDBContext()
        {
    

        }
        public PubDBContext(DbContextOptions<PubDBContext> options) : base(options)
        {
    

        }
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
    
            base.OnConfiguring(optionsBuilder);

        }
    }
}

3.PubController

using DotNetCore.CAP;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;

namespace _01_Publisher.Controllers
{
    
    [Route("api/[controller]/[action]")]
    [ApiController]
    public class PubController : ControllerBase
    {
    
        private ICapPublisher _capBus;
        private PubDBContext _pubDBContext;

        public PubController(ICapPublisher capBus, PubDBContext pubDBContext)
        {
    
            this._capBus = capBus;
            this._pubDBContext = pubDBContext;
        }
        [HttpGet]
        public IActionResult SendMsg()
        {
    
        	// Introduced CAP, Publish subscribe ,Publish（ Subscribed routing keys （RoutingKey）, Published data （Query））
        	// Routing key settings , The party receiving the subscription , Receive subscriptions to via routing keys 
                _capBus.Publish("angel", contentObj: new Person {
     Id = 1, Name = "11" });
                return Content(" Send successfully ");
        }
    }
}

Subscriber

1.Startup.cs

    <PackageReference Include="DotNetCore.CAP.Dashboard" Version="3.1.2" />

public void ConfigureServices(IServiceCollection services)
        {
    
            services.AddControllersWithViews();
            // Injected database 
            services.AddDbContext<SubDBContext>(options => options.UseSqlServer(Configuration["ConnectionStrings:AngelDBContext"]));


            // register cap event 
            services.AddCap(x =>
            {
    
                x.UseEntityFramework<SubDBContext>();
                x.UseRabbitMQ(rb =>
                {
    
                    rb.HostName = "localhost";
                    rb.UserName = "admin";
                    rb.Password = "admin";
                    rb.Port = 5672;
                    rb.VirtualHost = "Angel2022";
                    rb.ExchangeName = "AngelCapExchange";
                    rb.QueueMessageExpires = 24 * 3600 * 10;  // Automatic deletion time of messages in the queue ( Default 10 God )
                });
				// Here is the introduction of the visualization panel 
                x.UseDashboard();// Use Cap Visualization panel 
            });
        }
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env, SubDBContext efCoreApp)
        {
    
            efCoreApp.Database.EnsureCreated();// The database does not exist and is automatically created 
        }

2.SubDBContext

using Microsoft.EntityFrameworkCore;

namespace _02_Subscriber
{
    
    public class SubDBContext : DbContext
    {
    
        public SubDBContext()
        {
    

        }
        public SubDBContext(DbContextOptions<SubDBContext> options) : base(options)
        {
    

        }
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
    
            base.OnConfiguring(optionsBuilder);

        }
    }
}

3.SubController

namespace _02_Subscriber.Controllers
{
    
    [Route("api/[controller]/[action]")]
    [ApiController]
    public class SubController : ControllerBase
    {
    
        private ILogger _log;
        public SubController(ILogger<SubController> log)
        {
    
            this._log = log;
        }

        [NonAction]
        // Find by marking , The routing key is angel The news of 
        [CapSubscribe("angel")]
        public void ReceiveMsg(Person str)
        {
    
            if(str!=null)
            {
    
                Console.WriteLine($" receive {
      str.Id}");
                _log.LogInformation($" I'm a subscriber , The content received is ：{
      str.Id},{
      str.Name}");
            }
        }
    }
}

Four 、 Run the project

1. Requesting a message API
2. see Cap panel

http://localhost:（ Running port ）/cap
```![ Insert picture description here ](https://img-blog.csdnimg.cn/0f752747ad3c417aba2328939dd7f227.png)