最近工作需要，在调研BMP产品（开源和商用），重点了解了activiti和它的商业产品Alfresco Process Services，这是java的体系，成熟，完善(三方开源库是java多年开源积累下的最宝贵的财富)，出身.neter的我自然就想看看.net世界里有没有类似的产品。于是就找到两篇关于elsa的文章，一篇是善友兄的《》，另一篇国庆兄的《》，于是还专门致电国庆兄了解elsa这个开源框架的状况，国庆兄很细致的给我作了分享和演示（为开源精神，分享精神点赞），感谢。

于是我也小试一把elsa，同时也把自己的小心得分享出来.

demo的思路很简单，就是从一个api中请求信息，显示出来，这里用到两个activity：一个SendHttpRequest，一个Writeline。

定义webapi服务：

namespace APIDemo.Controllers{    [ApiController]    [Route("[controller]")]    public class HomeController : ControllerBase    {        private readonly ILogger
    
      _logger;        public HomeController(ILogger
     
       logger)        {            _logger = logger;        }        [HttpGet]        public Person GetPerson()        {            _logger.LogInformation("请求person");            return new Person() { ID = 100, Name = "张三丰收", Age = 22, Sex = true };        }    }    public class Person    {        public int ID { get; set; }        public string Name { get; set; }        public int Age { get; set; }        public bool Sex { get; set; }    }}
     
    

定义elsa工作流：

using Elsa.Activities.Console.Activities;using Elsa.Activities.Http.Activities;using Elsa.Activities.Http.Parsers;using Elsa.Activities.Http.Services;using Elsa.Expressions;using Elsa.Scripting.JavaScript;using Elsa.Services;using Elsa.Services.Models;using Microsoft.Extensions.DependencyInjection;using System;using System.Threading.Tasks;namespace Elsa01{    class Program    {        async static Task Main(string[] args)        {            Console.WriteLine("回车开始");            Console.ReadLine();            var services = new ServiceCollection()              .AddElsa()              //注入Response返回格式              .AddScoped
    
     ()              //注入httpclient工厂              .AddHttpClient()              .AddActivity
     
      ()              .AddActivity
      
       ()              .BuildServiceProvider();            var invoker = services.GetService
       
        ();            await invoker.StartAsync
        
         ();            Console.WriteLine("回车结束");            Console.ReadLine();        }    }    /// 
         
 /// 定义工作流两个activity,一个是请求webapi，一个是显示请求结果 /// 
    public class PersonHandleWorkflow : IWorkflow    {        public void Build(IWorkflowBuilder builder)        {            builder                .StartWith
         
          (RequestAPI, "http5001") .Then
          
           (ShowMessage);        } void ShowMessage(WriteLine write) { //用javascript脚本来处理返回信息 write.TextExpression = new JavaScriptExpression
           
            ("'ID:'+lastResult('http5001').Content[\"id\"]+' Name:'+lastResult('http5001').Content[\"name\"]+' Age:'+lastResult('http5001').Content[\"age\"]"); } void RequestAPI(SendHttpRequest http) { //定义http发送参数 http.ContentType = "application/json"; http.Method = "get"; http.Url = new WorkflowExpression
            
             (LiteralEvaluator.SyntaxName, "https://localhost:5001/home"); } }}