本地服务之调用外部方法
下面首先说说如何开发一个本地服务：1.使用C#的接口定义服务契约，在接口中定义你方法和事件。并使用装饰该接口，用于说明这是一个本地服务的接口。
2.开发一个实现了该接口的类，用于实现你的逻辑。
3.创建一个工作流实例，并将该本地服务添加到工作流引擎中去。
我们开发一个简单的本地服务的例子，根据AccountID来修改Balance的值，并使用三种方式来调用：
1.定义一个Account类，代码如下(Account.cs)
using System; namespace CaryWorkflows { public class Account { private Int32 _id; private String _name = String.Empty; private Double _balance; public Int32 Id { get { return _id; } set { _id = value; } } public String Name { get { return _name; } set { _name = value; } } public Double Balance { get { return _balance; } set { _balance = value; } } } }
2.定义一个接口，需要ExternalDataExchange属性，代码如下(IAccountServices.cs)：
using System;using System.Workflow.Activities;namespace CaryWorkflows { public interface IAccountServices { Account AdjustBalance(Int32 id, Double adjustment); }}
3.实现该接口，代码如下():
using System;using System.Collections.Generic;namespace CaryWorkflows { public class AccountService : IAccountServices { private Dictionary<Int32, Account> _accounts= new Dictionary<int, Account>(); public AccountService() { Account account = new Account(); account.Id = 101; account.Name = "Neil Armstrong"; account.Balance = 100.00; _accounts.Add(account.Id, account); } public Account AdjustBalance(Int32 id, Double adjustment) { Account account = null; if (_accounts.ContainsKey(id)) { account = _accounts; account.Balance += adjustment; } return account; } }}
using System;using System.ComponentModel;using System.ComponentModel.Design;using System.Collections;using System.Drawing;using System.Linq;using System.Workflow.ComponentModel.Compiler;using System.Workflow.ComponentModel.Serialization;using System.Workflow.ComponentModel;using System.Workflow.ComponentModel.Design;using System.Workflow.Runtime;using System.Workflow.Activities;using System.Workflow.Activities.Rules;namespace WorkflowConsoleApplication5{ public sealed partial class Workflow1 : SequentialWorkflowActivity { private Int32 _id; private Double _adjustment; private Account _account; private IAccountServices _accountServices; public Int32 Id { get { return _id; } set { _id = value; } } public Double Adjustment { get { return _adjustment; } set { _adjustment = value; } } public Account Account { get { return _account; } set { _account = value; } }然后我们向工作流中拖入一个CodeActivity，Activity有一个方法OnActivityExecutionContextLoad(),我们通过该的IServiceProvider的GetService方法来获取本地服务，代码如下： protected override void OnActivityExecutionContextLoad(IServiceProvider provider) { base.OnActivityExecutionContextLoad(provider); _accountServices = provider.GetService(typeof(IAccountServices)) as IAccountServices; if (_accountServices == null) { throw new InvalidOperationException("Unable to retrieve IAccountServices from runtime"); } } public Workflow1() { InitializeComponent(); } private void codeActivity1_ExecuteCode(object sender, EventArgs e) { Account = _accountServices.AdjustBalance(Id, Adjustment); System.Console.WriteLine(Id+" "+Adjustment); } }}
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading;using System.Workflow.Runtime;using System.Workflow.Runtime.Hosting;using System.Workflow.Activities;namespace WorkflowConsoleApplication5{ class Program { static void Main(string[] args) { using(WorkflowRuntime workflowRuntime = new WorkflowRuntime()) { AutoResetEvent waitHandle = new AutoResetEvent(false); ExternalDataExchangeService dataservice = new ExternalDataExchangeService(); workflowRuntime.AddService(dataservice); AccountService accountService = new AccountService(); dataservice.AddService(accountService); Dictionary<String, Object> dic = new Dictionary<string, object>(); dic.Add("Id",2); dic.Add("Adjustment",23.25); workflowRuntime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) {waitHandle.Set();}; workflowRuntime.WorkflowTerminated += delegate(object sender, WorkflowTerminatedEventArgs e) { Console.WriteLine(e.Exception.Message); waitHandle.Set(); }; WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(WorkflowConsoleApplication5.Workflow1),dic); instance.Start(); waitHandle.WaitOne(); } } }}
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