基于微软并行计算的工作流解决方案 (1) Parallel Activity
在微软WF4中有一个Parallel活动，它可以模拟并行执行，但可惜的是Parallel活动并不是一个真正意义上的并行计算方案，实际上Parallel利用了一个线程去分时间段执行下面的各个分支。
今天，我们要做的就是基于Parallel活动和微软.net framework 4中的并行任务Task，构造一个实际的并行工作流。并将它扩展为通用的并行工作流解决方案。
我们首先构造一个虚拟的订单处理流程，它包含主要三个活动
(1) 订单初始化
(2) 将订单有关信息拷贝到零件数据库(Part DB)
(3) 将订单有关信息拷贝到车辆数据库(Vehicle DB)
(4) 结束订单
传统的做法是构造一个服务，顺序执行(1)->(2)->(3),但在实际业务过程中，一旦订单初始化后，2,3流程没有先后次序关系，可以并发执行。
来看业务流程图 CloseOrder Workflow (FlowChart):
首先我们定义一个简单的Order类
public
class
Order
{
public
Guid Id {
get
;
set
;}
public
string
Customer {
get
;
set
; }
public
string
PartNumber {
get
;
set
; }
public
int
Quantity {
get
;
set
; }
public
OrderStatus Status {
get
;
set
; }
}
public
enum
OrderStatus
{
Initilized,
InProcess,
Cancelled,
Failed,
Succeeded
}
然后分别模拟零件数据库同步活动和车辆数据库同步活动。
public
class
PartDBReplicationActivity : NativeActivity
{
public
InOutArgument
<
Order
>
OrderInActivity {
get
;
set
; }
protected
override
void
Execute(NativeActivityContext context)
{
//
Console.WriteLine("PartDBReplication Activity starts at:{0}",DateTime.Now.ToString());
Order order
=
context.GetValue(OrderInActivity);
order.Status
=
OrderStatus.InProcess;
//
Call Part service
Thread.Sleep(
5000
);
//
Console.WriteLine("PartDBReplication Activity ends at {0}.\r\n", DateTime.Now.ToString());
}
}
public
class
VehicleDBReplicationActivity : NativeActivity
{
public
InOutArgument
<
Order
>
OrderInActivity {
get
;
set
; }
protected
override
void
Execute(NativeActivityContext context)
{
//
Console.WriteLine("VehicleDBReplication Activity starts at:{0}", DateTime.Now.ToString());
Order order
=
context.GetValue(OrderInActivity);
order.Status
=
OrderStatus.InProcess;
//
Call Vehicle service
Thread.Sleep(
5000
);
//
Console.WriteLine("VehicleDBReplication Activity ends at {0}.\r\n", DateTime.Now.ToString());
}
}
两个活动分别要执行5秒钟（Thread.Sleep(5000)),但是由于并行，它们实际应该总共只要花5秒。
再来看订单初始化活动
public
class
OpenOrderActivity : NativeActivity
{
public
InOutArgument
<
Order
>
OrderInActivity {
get
;
set
; }
protected
override
void
Execute(NativeActivityContext context)
{
Order order
=
new
Order();
order.Id
=
Guid.NewGuid();
order.PartNumber
=
"
10506
"
;
order.Customer
=
"
CustomerA
"
;
order.Quantity
=
1
;
order.Status
=
OrderStatus.Initilized;
context.SetValue(OrderInActivity, order);
}
}
结束订单
public
class
CloseOrderActivity : NativeActivity
{
public
InOutArgument
<
Order
>
OrderInActivity {
get
;
set
; }
protected
override
void
Execute(NativeActivityContext context)
{
//
Console.WriteLine("CloseOrder Activity starts at:{0}", DateTime.Now.ToString());
Order order
=
context.GetValue(OrderInActivity);
order.Status
=
OrderStatus.Succeeded;
//
Console.WriteLine("CloseOrder Activity ends at {0}.", DateTime.Now.ToString());
//
Console.WriteLine("");
}
}
添加我们定制的活动到主工作流活动前请先编译项目，新的定制活动就会出现在Toolbox 的最上面。 我们运行一下整个流程
class
Program
{
static
void
Main(
string
[] args)
{
DateTime dtStart
=
DateTime.Now;
Console.WriteLine(
"
CloseOrder workflow starts at:{0}
"
, dtStart);
Console.WriteLine(
"
--------------------------------------------------------------
"
);
WorkflowInvoker.Invoke(
new
CloseOrderWorkflow());
//
WorkflowInvoker.Invoke(new CloseOrderParallelWorkflow());
Console.WriteLine(
"
--------------------------------------------------------------
"
);
DateTime dtEnd
=
DateTime.Now;
Console.WriteLine(
"
CloseOrder workflow ends at:{0}
"
, dtEnd.ToString());
Console.WriteLine(
"
Total time elapsed in seconds :{0}
"
,( dtEnd
-
dtStart).Seconds.ToString());
Console.Read();
}
}
看看运行结果，
奇怪，整个活动花了10秒，Parallel活动的分支不是真正意义上的并行，主要原因我们刚才说过工作流中的Parallel利用了一个线程模拟分支并行的，我们的Thread.Sleep阻塞了其他分支的运行，导致整个流程运行实际时间等于串行执行这四个活动。
下一节我们将要利用.net framework4里面的Parallel Task去实现真正意义的并行工作流。
P.S. CloseOrderWorkflow.xaml 源代码 (项目命名空间为ParallelTask)
<
Activity
mc:Ignorable
="sap"
x:Class
="ParallelTask.CloseOrderWorkflow"
sap:VirtualizedContainerService.HintSize
="654,676"
mva:VisualBasic.Settings
="Assembly references and imported namespaces for internal implementation"
xmlns
="http://schemas.microsoft.com/netfx/2009/xaml/activities"
xmlns:av
="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:local
="clr-namespace:ParallelTask"
xmlns:mc
="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:mv
="clr-namespace:Microsoft.VisualBasic;assembly=System"
xmlns:mva
="clr-namespace:Microsoft.VisualBasic.Activities;assembly=System.Activities"
xmlns:s
="clr-namespace:System;assembly=mscorlib"
xmlns:s1
="clr-namespace:System;assembly=System"
xmlns:s2
="clr-namespace:System;assembly=System.Xml"
xmlns:s3
="clr-namespace:System;assembly=System.Core"
xmlns:sa
="clr-namespace:System.Activities;assembly=System.Activities"
xmlns:sad
="clr-namespace:System.Activities.Debugger;assembly=System.Activities"
xmlns:sap
="http://schemas.microsoft.com/netfx/2009/xaml/activities/presentation"
xmlns:scg
="clr-namespace:System.Collections.Generic;assembly=System"
xmlns:scg1
="clr-namespace:System.Collections.Generic;assembly=System.ServiceModel"
xmlns:scg2
="clr-namespace:System.Collections.Generic;assembly=System.Core"
xmlns:scg3
="clr-namespace:System.Collections.Generic;assembly=mscorlib"
xmlns:sd
="clr-namespace:System.Data;assembly=System.Data"
xmlns:sl
="clr-namespace:System.Linq;assembly=System.Core"
xmlns:st
="clr-namespace:System.Text;assembly=mscorlib"
xmlns:x
="http://schemas.microsoft.com/winfx/2006/xaml"
>
<
Flowchart
sad:XamlDebuggerXmlReader.FileName
="C:\Project\Labs\Parallel Execution\ParallelTask\ParallelTask\CloseOrderWorkflow.xaml"
sap:VirtualizedContainerService.HintSize
="614,636"
>
<
Flowchart.Variables
>
<
Variable
x:TypeArguments
="local:Order"
Name
="OrderInProcess"
/>
</
Flowchart.Variables
>
<
sap:WorkflowViewStateService.ViewState
>
<
scg3:Dictionary
x:TypeArguments
="x:String, x:Object"
>
<
x:Boolean
x:Key
="IsExpanded"
>
False
</
x:Boolean
>
<
av:Point
x:Key
="ShapeLocation"
>
270,2.5
</
av:Point
>
<
av:Size
x:Key
="ShapeSize"
>
60,75
</
av:Size
>
<
av:PointCollection
x:Key
="ConnectorLocation"
>
300,77.5 300,107.5 290,107.5 290,119
</
av:PointCollection
>
</
scg3:Dictionary
>
</
sap:WorkflowViewStateService.ViewState
>
<
Flowchart.StartNode
>
<
FlowStep
x:Name
="__ReferenceID0"
>
<
sap:WorkflowViewStateService.ViewState
>
<
scg3:Dictionary
x:TypeArguments
="x:String, x:Object"
>
<
av:Point
x:Key
="ShapeLocation"
>
190,119
</
av:Point
>
<
av:Size
x:Key
="ShapeSize"
>
200,22
</
av:Size
>
<
av:PointCollection
x:Key
="ConnectorLocation"
>
290,141 290,171 290,175.5
</
av:PointCollection
>
</
scg3:Dictionary
>
</
sap:WorkflowViewStateService.ViewState
>
<
local:OpenOrderActivity
sap:VirtualizedContainerService.HintSize
="200,22"
OrderInActivity
="[OrderInProcess]"
/>
<
FlowStep.Next
>
<
FlowStep
x:Name
="__ReferenceID2"
>
<
sap:WorkflowViewStateService.ViewState
>
<
scg3:Dictionary
x:TypeArguments
="x:String, x:Object"
>
<
av:Point
x:Key
="ShapeLocation"
>
190,175.5
</
av:Point
>
<
av:Size
x:Key
="ShapeSize"
>
200,49
</
av:Size
>
<
av:PointCollection
x:Key
="ConnectorLocation"
>
290,224.5 290,254.5 290,269
</
av:PointCollection
>
</
scg3:Dictionary
>
</
sap:WorkflowViewStateService.ViewState
>
<
Parallel
sap:VirtualizedContainerService.HintSize
="554,86"
>
<
local:PartDBReplicationActivity
sap:VirtualizedContainerService.HintSize
="200,40"
OrderInActivity
="[OrderInProcess]"
/>
<
local:VehicleDBReplicationActivity
sap:VirtualizedContainerService.HintSize
="200,40"
OrderInActivity
="[OrderInProcess]"
/>
</
Parallel
>
<
FlowStep.Next
>
<
FlowStep
x:Name
="__ReferenceID1"
>
<
sap:WorkflowViewStateService.ViewState
>
<
scg3:Dictionary
x:TypeArguments
="x:String, x:Object"
>
<
av:Point
x:Key
="ShapeLocation"
>
190,269
</
av:Point
>
<
av:Size
x:Key
="ShapeSize"
>
200,22
</
av:Size
>
</
scg3:Dictionary
>
</
sap:WorkflowViewStateService.ViewState
>
<
local:CloseOrderActivity
sap:VirtualizedContainerService.HintSize
="200,22"
OrderInActivity
="[OrderInProcess]"
/>
</
FlowStep
>
</
FlowStep.Next
>
</
FlowStep
>
</
FlowStep.Next
>
</
FlowStep
>
</
Flowchart.StartNode
>
<
x:Reference
>
__ReferenceID0
</
x:Reference
>
<
x:Reference
>
__ReferenceID1
</
x:Reference
>
<
x:Reference
>
__ReferenceID2
</
x:Reference
>
</
Flowchart
>
</
Activity
>