坚持学习WF(7):流程控制(Flow Control)

usingSystem;
usingSystem.ComponentModel;
usingSystem.Workflow.ComponentModel;
usingSystem.Workflow.Activities;
usingSystem.Collections.Generic;

namespaceCaryWorkflows
{
publicsealedpartialclassReplicatorWorkflow:SequentialWorkflowActivity
{
publicstaticDependencyPropertyInputListProperty
=System.Workflow.ComponentModel.DependencyProperty.Register(
"InputList",typeof(List<String>),typeof(ReplicatorWorkflow));
[Description("Alistofstringstoprocess")]
[Category("FlowControl")]
[Browsable(true)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
publicList<String>InputList
{
get
{
return((List<String>)(base.GetValue(ReplicatorWorkflow.InputListProperty)));
}
set
{
base.SetValue(ReplicatorWorkflow.InputListProperty,value);
}
}

publicReplicatorWorkflow()
{
InitializeComponent();
}
privatevoidcodeActivity1_ExecuteCode(objectsender,EventArgse)
{
Objectdata=String.Empty;
if(senderisActivity)
{
if(((Activity)sender).ParentisReplicatorActivity)
{
ReplicatorActivityrep=((Activity)sender).ParentasReplicatorActivity;
data=rep.InitialChildData[rep.CurrentIndex];
}
}
Console.WriteLine("CodeActivityinstancedata:{0}",data);
}
}
}

1.Replicator活动的ExecutionType属性必须设置为Sequential或Parallel，ExecutionType属性指示复制的子活动
实例是以并行方式还是顺序方式执行。如果是以并行方式执行，则将在ReplicatorActivity活动执行时创建所有实例；如
果是以顺序方式执行，则将依次执行子活动的每个实例，即：前一个实例完成后在执行下一个实例。
2.必须填充InitialchildData集合属性，以便为子活动的每个复制实例提供数据。它会跟据InitialChildData集合中成
员的个数创建容器内Activity个实例个数，这个例子中我们使用依赖属性InputList来填充该集合。
3.如果设置UntilCondition属性，当UntilCondition条件满足刊，Replicator会取消或中断正在运行的所有实例，结
束该结点.

宿主程序就不写了，执行的结果为CodeActivity会被多次执行，这取决你InitialchildData的数量。如下：
CodeActivityinstancedata：one
CodeActivityinstancedata：two
CodeActivityinstancedata：three

这里ExecutionType属性设置为Sequential，如果设置为Parallel，则就不正常了，会显示最后一个list的内容，如下：
CodeActivityinstancedata：three
CodeActivityinstancedata：three
CodeActivityinstancedata：three
原因是使用Sequential时子活动一次创建一个实例，执行完了一个在执行另一个，CurrentIndex的数值是逐渐增加的。如
果设置为Parallel，子活动是并行的。第一个活动刚执行的时候CurrentIndex的值就已经增加到最后一个了。

下面我们在来实现一个并行的Workflow，即将Replicator活动的ExecutionType属性设置为Parallel。工作流设计如下图：



这个例子中我们自定义一个活动ConsoleMessageActivity，它有一个Message属性可以接收工作流给每个实例传入的参数。
代码如下(ConsoleMessageActivity.cs)：
usingSystem;
usingSystem.ComponentModel;
usingSystem.Workflow.ComponentModel;

namespaceCaryWorkflows
{
publicpartialclassConsoleMessageActivity:Activity
{
publicstaticDependencyPropertyMessageProperty
=System.Workflow.ComponentModel.DependencyProperty.Register(
"Message",typeof(string),typeof(ConsoleMessageActivity));
[Description("AStringmessagetowritetotheConsole")]
[Category("FlowControl")]
[Browsable(true)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
publicstringMessage
{
get
{
return((string)(base.GetValue(
ConsoleMessageActivity.MessageProperty)));
}
set
{
base.SetValue(ConsoleMessageActivity.MessageProperty,value);
}
}

publicConsoleMessageActivity()
{
InitializeComponent();
}
protectedoverrideActivityExecutionStatusExecute(
ActivityExecutionContextexecutionContext)
{
if(Message!=null)
{
Console.WriteLine(Message);
}
returnbase.Execute(executionContext);
}
}
}

整个工作流的代码如下(ReplicatorParallelWorkflow.cs):

usingSystem;
usingSystem.ComponentModel;
usingSystem.Workflow.ComponentModel;
usingSystem.Workflow.Activities;
usingSystem.Collections.Generic;

namespaceCaryWorkflows
{
publicsealedpartialclassReplicatorParallelWorkflow:
SequentialWorkflowActivity
{
publicstaticDependencyPropertyInputListProperty
=System.Workflow.ComponentModel.DependencyProperty.Register(
"InputList",typeof(List<String>),
typeof(ReplicatorParallelWorkflow));
[Description("Alistofstringstoprocess")]
[Category("FlowControl")]
[Browsable(true)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
publicList<String>InputList
{
get
{
return((List<String>)(base.GetValue(ReplicatorParallelWorkflow.InputListProperty)));
}
set
{
base.SetValue(ReplicatorParallelWorkflow.InputListProperty,value);
}
}
publicReplicatorParallelWorkflow()
{
InitializeComponent();
}
privatevoidreplicatorActivity1_ChildInitialized(objectsender,ReplicatorChildEventArgse)
{
//ConsoleMessageActivitycma=((SequenceActivity)e.Activity).Activities[0]asConsoleMessageActivity;

ConsoleMessageActivitycma=e.Activity.GetActivityByName("consoleMessageActivity1")
asConsoleMessageActivity;
if(cma!=null)
{
cma.Message=e.InstanceDataasString;
}
}

}
}

1.InputList：用于给工作流传入参数。
2.ChildInitialized事件：当子活动创建的时候执行，可以将工作流的InputList集合的值正确的传给
ConsoleMessageActivity活动中的Message属性。
下面我们看看如果找到并引用ConsoleMessageActivity活动:
首先使用ReplicatorChildEventArgs参数的Activity属性找到根活动，在这个工作流中就是Sequence活动，然后在通过
GetActivityByName方法找到ConsoleMessageActivity。