WF中的序列化与反序列化

WF中的工作流有两种方式，一种是代码的模式，还是一种就是.xoml的模式，这两者之间是可以进行相互转换的，这就是WF中提供的序列化
和反序列化支持。WF框架中以下几个比较重要的类：

• WorkflowMarkupSerializer 类是序列化基础结构中使用的序列化基类型。此类型为序列化提供一些实现序列化规则的基本服务。该类
  的Serialize方法可以从内存中的工作流模型创建Markup文件，Deserialize是它的相反操作。
• ActivityMarkupSerializer 类从 WorkflowMarkupSerializer 类继承。此类型用于序列化所有基本活动。基本活动是复合活动之外的活动。
• CompositeActivityMarkupSerializer 类从 ActivityMarkupSerializer 类继承，它为复合活动提供序列化。CompositeActivityMarkupSerializer
  增加更多方法以处理子活动，子活动可以使用它们自己的序列化提供程序来序列化。

1.下面的例子我们首先用代码的方式创建一个工作流，代码如下：

private static Activity CreateWorkflow()
{
    CaryBaseWorkflow workflow = new CaryBaseWorkflow();
    workflow.Name = "CaryWorkflow";
            
    IfElseActivity ifElse = new IfElseActivity("ifElseActivity1");
    IfElseBranchActivity branch = new IfElseBranchActivity("ifElseBranchActivity1");

    //2.add a rule condition to the branch
    RuleConditionReference ruleCondition = new RuleConditionReference();
    ruleCondition.ConditionName = "Condition";
    branch.Condition = ruleCondition;
            
    //0.1.Code Condition
    //CodeCondition condition = new CodeCondition();            
    //ActivityBind bind = new ActivityBind("CaryWorkflow", "Condition");
    //condition.SetBinding(CodeCondition.ConditionEvent, bind);
    //branch.Condition = condition;
            
    CaryPrintActivity caryPrintActivity = new CaryPrintActivity();
    caryPrintActivity.Name = "caryPrintActivity1";
    caryPrintActivity.Message = "您输入的数字大于0";
    branch.Activities.Add(caryPrintActivity);            
    ifElse.Activities.Add(branch);
            
    branch = new IfElseBranchActivity("ifElseBranchActivity2");            
    caryPrintActivity = new CaryPrintActivity();
    caryPrintActivity.Name = "caryPrintActivity2";
    caryPrintActivity.Message = "您输入的数字小于等于0";
    branch.Activities.Add(caryPrintActivity);            
    ifElse.Activities.Add(branch);
            
    workflow.Activities.Add(ifElse);
    return workflow;
}

CaryBaseWorkflow 类和自定义活动CaryPrintActivity 请查看无代码的工作流创作模式一文中.

2.然后将内存中的工作流序列化到文件中,代码如下：

private static void SerializeWorkflow(Activity workflow, String fileName)
{
    try
    {
        using (XmlWriter xmlWriter = XmlWriter.Create(fileName))
        {
            WorkflowMarkupSerializer markupSerializer= new WorkflowMarkupSerializer();
            markupSerializer.Serialize(xmlWriter, workflow);
        }
     }
     catch (Exception e)
     {
            Console.WriteLine("Exception during serialization: {0}",e.Message);
     }
 }

3.然后我们可以使用如下代码来测试，代码如下：

static void Main(string[] args)
{
    Activity workflow = CreateWorkflow();            
    SerializeWorkflow(workflow, "SerializedWorkflow.xoml");
    using (WorkflowRuntime runtime = new WorkflowRuntime())
    {
        AutoResetEvent waitHandle = new AutoResetEvent(false);
        runtime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) 
        { waitHandle.Set(); };
        Console.WriteLine("开始执行工作流");
        Dictionary<String, Object> paras = new Dictionary<string, object>();
        paras.Add("Number", 6);
        try
        {       
            //0.SerialezeWorkflow Demo
            XmlReader reader = XmlReader.Create("SerializedWorkflow.xoml");
            WorkflowInstance instance = runtime.CreateWorkflow(reader, null, paras);
            instance.Start();

        }
        catch (WorkflowValidationFailedException e)
        {
            foreach (ValidationError error in e.Errors)
            {
                Console.WriteLine(error.ErrorText);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
        waitHandle.WaitOne();          
        Console.WriteLine("工作流执行完成\n\r");                
    }
}

上面测试代码中我们首先使用代码的方式创建工作流，然后在将该工作流序列化到SerializedWorkflow.xoml中，最后我们使用该工作流。

4.上面的例子中我们直接将SerializedWorkflow.xoml加载到Runtime中，这样只有当工作流实例执行的时候才能发现该工作流是否通过验证。
我们还可以将该工作流编译到DLL中，这样就可以在编译时对该工作流进行类型检查。
4.1.编译工作流时我们就创建了一个新的类型，所以在上面的CreateWorkflow中添加如下代码设置X:Class属性。

workflow.Activities.Add(ifElse);
//1.Compile Demo
workflow.SetValue(WorkflowMarkupSerializer.XClassProperty, "CaryWF.CompileWorkflowClass");
return workflow;

4.2.下面是编译工作流的方法：

private static void CompileWorkflow(String fileName, String assemblyName)
{
     WorkflowCompiler compiler = new WorkflowCompiler();
     WorkflowCompilerParameters parameters = new WorkflowCompilerParameters();
     parameters.OutputAssembly = assemblyName;
     parameters.ReferencedAssemblies.Add("CaryWFLib.dll");

     //2.add the .rules file for this workflow as a resource
     //Rule的格式要固定这样的
      parameters.EmbeddedResources.Add("CaryWF.CompileWorkflowClass.rules");

     WorkflowCompilerResults results = compiler.Compile(parameters, fileName);
     if (results.Errors.Count > 0)
     {
         foreach (System.CodeDom.Compiler.CompilerError error in results.Errors)
         {
            Console.WriteLine("编译错误:行{0}: {1}",error.Line, error.ErrorText);
         }
     }
 }

4.3.注意上面将规则文件增加为程序集的嵌入资源的时候，该规则的命名方式必须包含命名空间和工作流类。

4.4.除了使用WorkflowCompiler类对工作流进行编译，我们还可以使用命令行的方式wfc.exe，格式如下：

 wfc.exe SerializedWorkflow.xoml /target:assembly 
 /debug:- /resource:CaryWF.CompileWorkflowClass.rules 
 /reference:CaryWFLib.dll /out:CaryCompile.dll

5.再次测试，代码如下：

static void Main(string[] args)
{
    Activity workflow = CreateWorkflow();            
    SerializeWorkflow(workflow, "SerializedWorkflow.xoml");
    //1.Compile Demo
    CompileWorkflow("SerializedWorkflow.xoml", "CaryCompile.dll");            
    using (WorkflowRuntime runtime = new WorkflowRuntime())
    {
        AutoResetEvent waitHandle = new AutoResetEvent(false);
        runtime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) 
        { waitHandle.Set(); };
        Console.WriteLine("开始执行工作流");
        Dictionary<String, Object> paras = new Dictionary<string, object>();
        paras.Add("Number", 6);
        try
        {              
            Type workflowType = Type.GetType("CaryWF.CompileWorkflowClass,CaryCompile");
            WorkflowInstance instance = runtime.CreateWorkflow(workflowType, paras);
            instance.Start();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
        waitHandle.WaitOne();          
        Console.WriteLine("工作流执行完成\n\r");                
    }
}

由于工作流进行了编译,所以catch中的就不需要捕获验证失败的特定异常了。

6.上面我们将内存中的工作流序列化到xoml文件中，我们也可以反序列化。

private static Activity DeserializeFromMarkup(String fileName)
{
    Activity workflow = null;
    try
    {                
        ServiceContainer container = new ServiceContainer();
        TypeProvider provider = new TypeProvider(container);             
        provider.AddAssembly(typeof(CaryWFLib.CaryBaseWorkflow).Assembly);
        container.AddService(typeof(ITypeProvider), provider);
        
        DesignerSerializationManager dsm= new DesignerSerializationManager(container);

        using (dsm.CreateSession())
        {
            using (XmlReader xmlReader = XmlReader.Create(fileName))
            {
                //deserialize the workflow from the XmlReader
                WorkflowMarkupSerializer markupSerializer = new WorkflowMarkupSerializer();
                workflow = markupSerializer.Deserialize(dsm, xmlReader) as Activity;

                if (dsm.Errors.Count > 0)
                {
                    foreach (WorkflowMarkupSerializationException error in dsm.Errors)
                    {
                        Console.WriteLine("Deserialization error: {0}", error);
                    }
                }
            }
        }
    }
    catch (Exception e)
    {
        Console.WriteLine("Exception during deserialization: {0}",e.Message);
    }
    return workflow;
}

就简单介绍这些。