NetCore使用DotNetCore.CAP框架

CAP 是一个EventBus，同时也是一个在微服务或者SOA系统中解决分布式事务问题的一个框架。它有助于创建可扩展，可靠并且易于更改的微服务系统。

这个项目中使用到SqlServer(数据库方面大同小异)、MongoDb、Kafka、RabbitMq以及Consul

1：引入相关Nuget就行

DotNetCore.CAP
DotNetCore.CAP.Kafka
DotNetCore.CAP.RabbitMQ
DotNetCore.CAP.SqlServer
DotNetCore.CAP.MongoDB
DotNetCore.CAP.Dashboard

2：在program中使用（我的项目是基于net6的）

builder.Services.AddDbContext<AppDbContext>(opt =>
{
    opt.UseSqlServer(builder.Configuration.GetSection("CAP:SqlServer").Value);
});
//Options, If you are using MongoDB
builder.Services.AddSingleton<IMongoClient>(new MongoClient(builder.Configuration.GetSection("CAP:MongoDB").Value));

builder.Services.AddCap(x =>
{
    // If you are using EF, you need to add the configuration：
    //x.UseEntityFramework<AppDbContext>(); //Options, Notice: You don't need to config x.UseSqlServer(""") again! CAP can autodiscovery.

    // If you are using ADO.NET, choose to add configuration you needed：
    x.UseSqlServer(builder.Configuration.GetSection("CAP:SqlServer").Value);
    //x.UseMySql("Your ConnectionStrings");
    //x.UsePostgreSql("Your ConnectionStrings");

    // If you are using MongoDB, you need to add the configuration：
    //x.UseMongoDB(opt => {
    //    opt.DatabaseConnection = builder.Configuration.GetSection("CAP:MongoDB").Value;
    //});  //注意，仅支持MongoDB 4.0+集群

    // CAP support RabbitMQ,Kafka,AzureService as the MQ, choose to add configuration you needed：
    x.UseRabbitMQ(opt =>
    {
        opt.HostName = "192.168.1.7";
        opt.Port = 5672;
        opt.UserName = "admin";
        opt.Password = "admin";
        opt.VirtualHost = "/";
    });
    x.UseKafka(opt =>
    {
        opt.Servers = "192.168.1.12:9092";
    });
    //x.UseRabbitMQ(builder.Configuration.GetSection("CAP:RabbitMQ").Value);
    x.UseDashboard();
    DiscoveryOptions discoveryOptions = new DiscoveryOptions();
    discoveryOptions.CurrentNodePort = 5173;
    builder.Configuration.Bind(discoveryOptions);
    // Register to Consul
    x.UseDiscovery(d =>
    {
        d.DiscoveryServerHostName = "localhost";
        d.DiscoveryServerPort = 8500;
        d.CurrentNodeHostName = "localhost";
        d.CurrentNodePort = 5222;
        d.NodeId = "1";
        d.NodeName = "fanlin";
        d.Scheme = "http";
        d.MatchPath = "/api/HealthCheck";
    });
    x.FailedRetryInterval = 10;//失败重试的间隔时间
    x.FailedRetryCount = 10;//失败重试的次数
    x.FailedThresholdCallback = info =>
    {
        Console.WriteLine("Publish Message Error::" + info.Message);
    };
    //x.UseKafka("ConnectionString");
    //x.UseAzureServiceBus("ConnectionString");
    //x.UseAmazonSQS();
});

3：新建PublishController，主要用于发布，代码很简单。代码如下

/// <summary>
    /// CAP的消费是自动消费的
    /// </summary>
    [Route("api/[controller]")]
    [ApiController]
    public class PublishController : ControllerBase
    {
        private static string _publishName = "FanlinCAPDemo.Servces.Test";
        private readonly ICapPublisher _capBus;
        private readonly IConfiguration _configuration;
        private readonly AppDbContext _appDbContext;

        public PublishController(ICapPublisher capPublisher, IConfiguration configuration, AppDbContext appDbContext)
        {
            _capBus = capPublisher;
            _configuration = configuration;
            _appDbContext = appDbContext;
        }
        [HttpGet]
        [Route("no/transaction")]//根目录
        public async Task<IActionResult> WithoutTransaction()
        {
            Console.WriteLine("普通----无事务");
            var user = _appDbContext.Users.Find("1");
            await _capBus.PublishAsync(_publishName, user);//应该把数据写到publish表
            return Ok();
        }
        [HttpGet]
        [Route("adonet/transaction")]
        public IActionResult AdonetWithTransaction()
        {
            Console.WriteLine("普通事务---连接字符串----事务");
            var user = _appDbContext.Users.Find("1");
            using (var connection = new SqlConnection(_configuration.GetSection("CAP:SqlServer").Value))
            {
                using (var transaction = connection.BeginTransaction(_capBus, true))
                {
                    //your business logic code

                    _capBus.Publish(_publishName, user);
                }
            }

            return Ok();
        }
        [HttpGet]
        [Route("ef/transaction")]
        public IActionResult EntityFrameworkWithTransaction()
        {
            Console.WriteLine("上下文---事务");
            var user = _appDbContext.Users.Find("1");
            //带header
            IDictionary<string, string?> dicHeader = new Dictionary<string, string?>();
            dicHeader.Add("Husband", "Fanlin");
            dicHeader.Add("Wife", "Baoting");
            dicHeader.Add("SumAge", "34");
            using (var trans = _appDbContext.Database.BeginTransaction(_capBus, autoCommit: true))
            {
                //your business logic code

                _capBus.Publish(_publishName, user, dicHeader);
            }

            return Ok();
        }
    }

4：新建ConsumerController 用于消费，代码很简单，需要注意，订阅需要标注特性CapSubscribe，其属性name就是发布者的_publishName，也可以顶一个多个group，在rabbitmq里面会自动新建相应的队列！代码如下

[Route("api/[controller]")]
    [ApiController]
    public class ConsumerController : ControllerBase
    {
        private readonly AppDbContext _context;
        private readonly IMongoClient _client;
        private readonly ICapPublisher _capBus;
        public ConsumerController(AppDbContext appDbContext, IMongoClient mongoClient, ICapPublisher iCapPublisher)
        {
            _context = appDbContext;
            _capBus = iCapPublisher;
            _client = mongoClient;
            var collection = _client.GetDatabase("MyCap").GetCollection<Users>("MyCap.User");
            collection.InsertOne(new Users()
            {
                UserID = "3",
                UserName = "范小包",
                UserPy = "fxb",
                UserPwd = "1234",
                department = "1",
                userRemark = "jkl",
                UserWb = "abc",
                headImageFile = "none"
            });
        }

        [NonAction]
        [CapSubscribe("FanlinCAPDemo.Servces.Test")]
        public void CheckReceivedMessage(Users users, [FromCap] CapHeader header)
        {
            Console.WriteLine($"{DateTime.Now} NoGroup Info:{users}，Header:{header.Count}");
        }
        [NonAction]
        [CapSubscribe("FanlinCAPDemo.Servces.Test", Group = "Group1")]
        public void CheckReceivedMessageGroup(Users users)
        {
            Console.WriteLine($"{DateTime.Now} NoGroup Info:{users}");
            //这里不支持事务 使用事务会报错 
            //using (var session = _client.StartTransaction(_capBus, autoCommit: false))
            //{
                var collection = _client.GetDatabase("test").GetCollection<BsonDocument>("test.collection");
                collection.InsertOne( new BsonDocument { { "hello", "world" } });

                _capBus.Publish("sample.rabbitmq.mongodb", DateTime.Now);

                //session.CommitTransaction();
            //}
        }
    }

5：调用接口，查看kafka和rabbitmq以及相关数据库的变化

a:RabbitMQ:

这里自动新建了两个队列，如果有定义group已group属性为准，如果没有，名称是自定义的

 b:Kafka

CAP自动创建了3个topic

 c:SqlServer

数据库会自动生成名为cap的数据库，里面有两张表，其中publish是发布的数据，receive是接收到的数据

 

 d:再来看Mongodb，这里是MongoDB的数据库，如果要使用事务，事务里面的数据库必须先存在

 e：如果你需要使用consul，只需要启动consul.exe即可，CAP框架会自动将服务注册,访问你的服务http://ip:port/cap,然后就可以通过界面看到相关数据了

 

 

 

以上就是CAP矿建的简单使用，这是大神杨晓东的作品，有关文档可参考

https://github.com/dotnetcore/CAP

https://cap.dotnetcore.xyz/user-guide/zh/getting-started/introduction/