一个适合于.NET Core的超轻量级工作流引擎:Workflow-Core

一、关于Workflow-Core

  近期工作上有一个工作流的开发需求,自己基于面向对象和职责链模式捣鼓了一套小框架,后来在github上发现一个轻量级的工作流引擎轮子:Workflow-Core,看完其wiki之后决定放弃之前自己造的轮子,使用这个开源项目来改造,也就有了这一篇博文。

  

  Workflow-Core是一个基于.NET Standard的轻量级工作流引擎,其GitHub地址为:https://github.com/danielgerlag/workflow-core,目前有超过1200+个star。它提供了FluentAPI、多任务、持久化以及并行处理的功能,适合于小型工作流、责任链的需求开发。

  由于Workflow-Core支持工作流长期运行,因此Workflow-Core支持以下多种数据源格式的持久化,可以通过安装不同的Provider包来实现对应的持久化:

  • (默认提供,用于测试和开发)内存
  • MongoDB
  • MS SQL Server
  • MySql
  • Sqlite
  • Redis
  • PostgreSQL

  立刻上手把,Nuget上安装一把,目前最新版本2.0.0:

PM> Install-Package WorkflowCore

二、Workflow-Core的基本使用

2.1 Hello World

  这里创建了一个.NET Core控制台应用程序,快速演示第一个Workflow-Core的Hello World,展示如何开始一个Workflow:

  (1)定义一个实现IWorkflow接口的Workflow:

    public class HelloWorldWorkflow : IWorkflow
    {
        public string Id => "HelloWorld";

        public int Version => 1;

        public void Build(IWorkflowBuilder<object> builder)
        {
            builder
                .StartWith<HelloWorld>()
                .Then<ActiveWorld>()
                .Then<GoodbyeWorld>();
        }
    }

  这里定义了一个HelloWorldWorkflow,其版本号为1,它有3个步骤:HelloWorld、ActiveWorld和GoodbyeWorld,会依次执行。

  (2)定义三个继承自StepBody类的步骤类:

    public class HelloWorld : StepBody
    {
        public override ExecutionResult Run(IStepExecutionContext context)
        {
            Console.WriteLine("Hello World!");
            return ExecutionResult.Next();
        }
    }

    public class ActiveWorld : StepBody
    {
        public override ExecutionResult Run(IStepExecutionContext context)
        {
            Console.WriteLine("I am activing in the World!");
            return ExecutionResult.Next();
        }
    }

    public class GoodbyeWorld : StepBody
    {
        public override ExecutionResult Run(IStepExecutionContext context)
        {
            Console.WriteLine("Goodbye World!");
            return ExecutionResult.Next();
        }
    }

  (3)ServiceCollection中注入Workflow-Core相关组件

    private static IServiceProvider ConfigureServices()
    {
        IServiceCollection services = new ServiceCollection();
        services.AddLogging(); // WorkflowCore需要用到logging service
        services.AddWorkflow();

        var serviceProvider = services.BuildServiceProvider();

        return serviceProvider;
    }

  (4)在Program.cs的Main方法中获取到注入的host并执行工作流

        public static void Main(string[] args)
        {
            var serviceProvider = ConfigureServices();
            var host = serviceProvider.GetService<IWorkflowHost>();
            host.RegisterWorkflow<HelloWorldWorkflow>();
            host.Start();

            // Demo1:Hello World
            host.StartWorkflow("HelloWorld");

            Console.ReadKey();
            host.Stop();
        }    

  这里传入的是Workflow的Id,Workflow-Core会根据Id去自动匹配最新版本的对应Workflow,运行结果如下:

  

2.2 If语句

  在工作流处理中,往往会有很多的条件判断,那么在Workflow-Core中也提供了直接的If功能,如下面这个IfStatementWorkflow所示:

    public class IfStatementWorkflow : IWorkflow<MyData>
    {
        public string Id => "if-sample";

        public int Version => 1;

        public void Build(IWorkflowBuilder<MyData> builder)
        {
            builder
                .StartWith<SayHello>()
                .If(data => data.Counter < 3).Do(then => then
                        .StartWith<PrintMessage>()
                            .Input(step => step.Message, data => "Outcome is less than 3")
                )
               .If(data => data.Counter < 5).Do(then => then
                        .StartWith<PrintMessage>()
                            .Input(step => step.Message, data => "Outcome is less than 5")
                )
                .Then<SayGoodbye>();
        }
    }

  这个传递进来的MyData的定义如下:

    public class MyData
    {
        public int Counter { get; set; }
    }

  当传递进来的MyData的Counter属性<3 或 <5时会有不同的分支进行逻辑的处理。

2.3 MySQL持久化支持

  想要将工作流配置持久化到MySQL,只需以下两步:

  (1)通过Nuget安装MySQL Provider包:

PM> Install-Package WorkflowCore.Persistence.MySQL

  (2)注入到ServiceCollection

services.AddWorkflow(x => x.UseMySQL(@"Server=127.0.0.1;Database=workflow;User=root;Password=password;", true, true));

  一旦启动,你就会发现Workflow-Core自动帮你创建了很多表用于持久化工作流配置和实例。

  

2.4 计划任务和循环任务

  Workflow-Core还集成了计划任务和循环任务的功能:

  (1)计划任务:比如在工作流步骤中设置一个延迟5分钟执行的计划任务

builder
    .StartWith(context => Console.WriteLine("Hello"))
    .Schedule(data => TimeSpan.FromSeconds(5)).Do(schedule => schedule
        .StartWith(context => Console.WriteLine("Doing scheduled tasks"))
    )
    .Then(context => Console.WriteLine("Doing normal tasks"));

  (2)循环任务:比如在工作流步骤中设置一个延迟5分钟进行的循环任务,知道Counter > 5才结束

builder
    .StartWith(context => Console.WriteLine("Hello"))
    .Recur(data => TimeSpan.FromSeconds(5), data => data.Counter > 5).Do(recur => recur
        .StartWith(context => Console.WriteLine("Doing recurring task"))
    )
    .Then(context => Console.WriteLine("Carry on"));

2.5 Saga支持

  了解分布式事务方案的童鞋应该都知道Saga,在Workflow-Core中也有支持,这是一个十分有用的功能:

  (1)比如:在创建一个客户信息之后,将其推送到Salesforce和ERP,如果推送过程中发生了错误,那么就通过重试进行补偿,并且重试有时间间隔。

      builder
            .StartWith<CreateCustomer>()
            .Then<PushToSalesforce>()
                .OnError(WorkflowErrorHandling.Retry, TimeSpan.FromMinutes(10))
            .Then<PushToERP>()
                .OnError(WorkflowErrorHandling.Retry, TimeSpan.FromMinutes(10));

  (2)又比如:当Task2发生异常时,Workflow-Core会帮助执行UndoTask2 和 UndoTask1 帮你回滚数据以恢复状态。

builder
    .StartWith<LogStart>()
    .Saga(saga => saga
        .StartWith<Task1>()
            .CompensateWith<UndoTask1>()
        .Then<Task2>()
            .CompensateWith<UndoTask2>()
        .Then<Task3>()
            .CompensateWith<UndoTask3>()
    )
    .OnError(Models.WorkflowErrorHandling.Retry, TimeSpan.FromMinutes(10))
    .Then<LogEnd>();

  更多Saga示例,请参考:https://github.com/danielgerlag/workflow-core/tree/master/src/samples/WorkflowCore.Sample17

三、在ASP.NET Core中使用Workflow-Core

3.1 注入与初始化

  (1)注入:使用AddWorkflow()扩展方法

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddWorkflow();
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        }

  (2)初始化:

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
            .......      
            app.UseWorkflow();
    }

  扩展方法如下:

    public static class ConfigureExtensions
    {
        public static IApplicationBuilder UseWorkflow(this IApplicationBuilder app)
        {
            var host = app.ApplicationServices.GetService<IWorkflowHost>();
            host.RegisterWorkflow<EdcWorkflow>();
            host.RegisterWorkflow<EdcDataWorkflow, EdcData>();
            host.Start();

            var appLifetime = app.ApplicationServices.GetService<IApplicationLifetime>();
            appLifetime.ApplicationStopping.Register(() =>
            {
                host.Stop();
            });

            return app;
        }
    }

  这里需要注意的就是:将你要用到的所有Workflow都事先进行Register注册。

3.2 通过DI获取使用  

  在你想要用到的地方,无论是Controller还是Service,通过依赖注入获取到Host,并使用它:

    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        private IWorkflowController _workflowService;

        public ValuesController(IWorkflowController workflowService)
        {
            _workflowService = workflowService;
        }

        // GET api/values
        [HttpGet]
        public async Task<IEnumerable<string>> Get()
        {
            await _workflowService.StartWorkflow("EdcWorkflow");
            return new string[] { "EdcWorkflow v1" };
        }

        // GET api/values/5
        [HttpGet("{id}")]
        public async Task<string> Get(int id)
        {
            await _workflowService.StartWorkflow("EdcDataWorkflow", new EdcData() { Id = id });
            return "EdcDataWorkflow v1";
        }
    }

  这两个Workflow的定义如下:

    public class EdcWorkflow : IWorkflow
    {
        public string Id => "EdcWorkflow";

        public int Version => 1;

        public void Build(IWorkflowBuilder<object> builder)
        {
            builder
                .StartWith<HelloWorld>()
                .Then<GoodbyeWorld>();
        }
    }

    public class EdcDataWorkflow : IWorkflow<EdcData>
    {
        public string Id => "EdcDataWorkflow";

        public int Version => 1;

        public void Build(IWorkflowBuilder<EdcData> builder)
        {
            builder
                .StartWith<HelloWorld>()
                .If(data => data.Id < 3).Do(then => then
                        .StartWith<PrintMessage>()
                            .Input(step => step.Message, data => "Passed Id is less than 3")
                )
               .If(data => data.Id < 5).Do(then => then
                        .StartWith<PrintMessage>()
                            .Input(step => step.Message, data => "Passed Id is less than 5")
                )
                .Then<GoodbyeWorld>();
        }
    }

  示例结果很简单:

  (1)api/values

  

  (2)api/values/1

  

四、小结

  Workflow-Core是一个适合.NET Core的优秀的轻量级工作流引擎,对于小型工作流和责任链类型的需求开发很适合,可以节约大量时间避免重复造轮子,将时间主要花在业务逻辑上面。当然,这里演示的示例只是众多功能特性中的一小部分,我只是选取了我用到的部分而已,大家有兴趣的话可以去GitHub上先给个star再仔细研究其wiki文档,应用到自己的项目中去。

  示例代码:https://github.com/EdisonChou/EDC.WorkflowCore.Sample

 

posted @ 2019-07-16 12:42 EdisonZhou 阅读(...) 评论(...) 编辑 收藏