前言

1.什么是工作流

工作流是OA系统比较重要的功能之一，主要在于企业流程协同审批，有效进行流程管理。

流程管理起源于生产组织和办公自动化领域，是针对日常工作中具有固定程序的活动提出的一个概念。目的是通过将工作分解成定义良好的任务、角色，按照一定的规则和过程来执行这些任务并对它们进行监控，达到提高办事效率、降低生产成本、提高企业生产经营管理水平和企业竞争力的目标。

现代计算机技术实现了工作流，是支持企业经营过程高效执行并监控其执行过程的计算机软件系统。工作流软件类似电脑桌面操作系统，操作系统驱动电脑各部件协同运转，工作流软件则驱动业务过程自动有序进行。

Workflow-Core地址：https://github.com/danielgerlag/workflow-core

一、Workflow-Core轻量级工作流引擎

1.安装包

Install-Package WorkflowCore
Microsoft.Extensions.Logging
Microsoft.Extensions.Logging.Debug

2.简单使用

2.1 定义步骤

1、步骤一

using System;
using System.Linq;
using WorkflowCore.Interface;
using WorkflowCore.Models;

namespace WorkflowCore.Sample01.Steps
{
    public class HelloWorld : StepBody
    {
        public override ExecutionResult Run(IStepExecutionContext context)
        {
            Console.WriteLine("Hello world");
            return ExecutionResult.Next();
        }
    }
}

2、步骤二

using Microsoft.Extensions.Logging;
using WorkflowCore.Interface;
using WorkflowCore.Models;

namespace WorkflowCore.Sample01.Steps
{
    public class GoodbyeWorld : StepBody
    {

        private ILogger _logger;

        public GoodbyeWorld(ILoggerFactory loggerFactory)
        {
            _logger = loggerFactory.CreateLogger<GoodbyeWorld>();
        }

        public override ExecutionResult Run(IStepExecutionContext context)
        {
            Console.WriteLine("Goodbye world");
            _logger.LogInformation("Hi there!");
            return ExecutionResult.Next();
        }
    }
}

2.2 定义工作流

using WorkflowCore.Interface;
using WorkflowCore.Models;
using WorkflowCore.Sample01.Steps;

namespace WorkflowCore.Sample01
{
    public class HelloWorldWorkflow : IWorkflow
    {
        public void Build(IWorkflowBuilder<object> builder)
        {
            builder                
                .UseDefaultErrorBehavior(WorkflowErrorHandling.Suspend)
                .StartWith<HelloWorld>()                
                .Then<GoodbyeWorld>();
        }

        public string Id => "HelloWorld";
            
        public int Version => 1;
                 
    }
}

2.3 启动工作流

using Microsoft.Extensions.DependencyInjection;
using WorkflowCore.Interface;
using WorkflowCore.Sample01;
using WorkflowCore.Sample01.Steps;

IServiceProvider serviceProvider = ConfigureServices();

//start the workflow host
var host = serviceProvider.GetService<IWorkflowHost>();
host.RegisterWorkflow<HelloWorldWorkflow>();
host.Start();

host.StartWorkflow("HelloWorld");

Console.ReadLine();
host.Stop();

static IServiceProvider ConfigureServices()
{
    //setup dependency injection
    IServiceCollection services = new ServiceCollection();
    services.AddLogging();
    services.AddWorkflow();
    //services.AddWorkflow(x => x.UseMongoDB(@"mongodb://localhost:27017", "workflow"));
    services.AddTransient<GoodbyeWorld>();

    var serviceProvider = services.BuildServiceProvider();

    return serviceProvider;
}

2.4 运行

二、Workflow-Core的流程配置

1.代码配置

public class MyWorkflow : IWorkflow
{
    public void Build(IWorkflowBuilder<MyData> builder)
    {    
        builder
           .StartWith<Task1>()
           .Then<Task2>()
           .Then<Task3>();
    }
}

2.JSON配置

{
  "Id": "HelloWorld",
  "Version": 1,
  "Steps": [
    {
      "Id": "Hello",
      "StepType": "MyApp.HelloWorld, MyApp",
      "NextStepId": "Bye"
    },        
    {
      "Id": "Bye",
      "StepType": "MyApp.GoodbyeWorld, MyApp"
    }
  ]
}

3.YAML配置

Id: HelloWorld
Version: 1
Steps:
- Id: Hello
  StepType: MyApp.HelloWorld, MyApp
  NextStepId: Bye
- Id: Bye
  StepType: MyApp.GoodbyeWorld, MyApp