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.流程事件

模型类

public class MyDataClass
{
    public string Value1 { get; set; }
}

2.1 定义步骤

1、步骤一

public class CustomMessage : StepBody
    {
        
        public string Message { get; set; }

        public override ExecutionResult Run(IStepExecutionContext context)
        {
            Console.WriteLine(Message);
            return ExecutionResult.Next();
        }
    }

2.2 定义工作流

public class EventSampleWorkflow : IWorkflow<MyDataClass>
{
    public string Id => "EventSampleWorkflow";
        
    public int Version => 1;
        
    public void Build(IWorkflowBuilder<MyDataClass> builder)
    {
        builder
            .StartWith(context => ExecutionResult.Next())
            .WaitFor("MyEvent", (data, context) => context.Workflow.Id, data => DateTime.Now)
                .Output(data => data.Value1, step => step.EventData)
            .Then<CustomMessage>()
                .Input(step => step.Message, data => "The data from the event is " + data.Value1)
            .Then(context => Console.WriteLine("workflow complete"));
    }
}

2.3 启动工作流

using Microsoft.Extensions.DependencyInjection;
using WorkflowCore.Interface;
using WorkflowCore.Sample04;

IServiceProvider serviceProvider = ConfigureServices();

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

var initialData = new MyDataClass();
var workflowId = host.StartWorkflow("EventSampleWorkflow", 1, initialData).Result;

Console.WriteLine("Enter value to publish");
string value = Console.ReadLine();
host.PublishEvent("MyEvent", workflowId, value);

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.AddWorkflow(x => x.UseSqlServer(@"Server=.;Database=WorkflowCore;Trusted_Connection=True;", true, true));
    //services.AddWorkflow(x => x.UsePostgreSQL(@"Server=127.0.0.1;Port=5432;Database=workflow;User Id=postgres;", true, true));
    //services.AddWorkflow(x => x.UseSqlite(@"Data Source=database.db;", true));            

    //services.AddWorkflow(x =>
    //{
    //    x.UseAzureSynchronization(@"UseDevelopmentStorage=true");
    //    x.UseMongoDB(@"mongodb://localhost:27017", "workflow9999");
    //});

    //services.AddWorkflow(x =>
    //{
    //    x.UseSqlServer(@"Server=.\SQLEXPRESS;Database=WorkflowCore;Trusted_Connection=True;", true, true);
    //    x.UseSqlServerLocking(@"Server=.\SQLEXPRESS;Database=WorkflowCore;Trusted_Connection=True;");
    //});

    //services.AddWorkflow(cfg =>
    //{
    //    var ddbConfig = new AmazonDynamoDBConfig() { RegionEndpoint = RegionEndpoint.USWest2 };

    //    cfg.UseAwsDynamoPersistence(new EnvironmentVariablesAWSCredentials(), ddbConfig, "sample4");
    //    cfg.UseAwsDynamoLocking(new EnvironmentVariablesAWSCredentials(), ddbConfig, "workflow-core-locks");
    //    cfg.UseAwsSimpleQueueService(new EnvironmentVariablesAWSCredentials(), new AmazonSQSConfig() { RegionEndpoint = RegionEndpoint.USWest2 });                
    //});

    //services.AddWorkflow(cfg =>
    //{
    //    cfg.UseRedisPersistence("localhost:6379", "sample4");
    //    cfg.UseRedisLocking("localhost:6379");
    //    cfg.UseRedisQueues("localhost:6379", "sample4");
    //    cfg.UseRedisEventHub("localhost:6379", "channel1");
    //});

    //services.AddWorkflow(x =>
    //{
    // x.UseMongoDB(@"mongodb://192.168.0.12:27017", "workflow");
    //x.UseRabbitMQ(new ConnectionFactory() { HostName = "localhost" });
    //x.UseRedlock(redis);
    //});


    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