I am trying to host a WF4 (RC) Service dynamically. I have a test solution with two projects. The first is a declarative workflow service library with one root Flowchart activity in it, and a simple custom code activity. The workflow service library does not depend on any other custom assemblies or references. The second is my host app, which in my test solution is just a console application.
In my host app, I am attempting to the use ActivityXamlServices to load the Xaml for the workflow service into an activity, and then use the WorkflowServiceHost to fire up a workflow instance using that activity.
As soon as I try to new up the WorkflowServiceHost object, I get this exception...
Cannot create unknown type '{clr-namespace:DeclarativeServiceLibrary1}CodeActivity1'.
If I remove CodeActivity1 from my Flowchart designer, everything runs fine. If I add a direct reference to the workflow service project from my host project and then create a WorkflowServiceHost using an instance of my Flowchart activity instead of the activity created from the Xaml, it also works fine.
It seems to not like using my CodeActivity for some reason when loaded dynamically.
Anyone have any ideas as to why I can't dynamically create my workflow service?
My code is as follows...
DeclarativeServiceLibrary1.Activity1.xaml...
<Activity mc:Ignorable="sap" x:Class="DeclarativeServiceLibrary1.Activity1" 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:DeclarativeServiceLibrary1" 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:p="http://schemas.microsoft.com/netfx/2009/xaml/servicemodel" 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: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:\dev\test\MyWorkflow\DeclarativeServiceLibrary1\Activity1.xaml" sap:VirtualizedContainerService.HintSize="614,636">
<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">300,77.5 300,107.5 300,165</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">172.5,165</av:Point>
<av:Size x:Key="ShapeSize">255,90</av:Size>
<av:PointCollection x:Key="ConnectorLocation">300,255 300,285 300,299.5</av:PointCollection>
</scg3:Dictionary>
</sap:WorkflowViewStateService.ViewState>
<p:Receive CanCreateInstance="True" sap:VirtualizedContainerService.HintSize="255,90" OperationName="MyOperation" ServiceContractName="MyContractName" />
<FlowStep.Next>
<FlowStep x:Name="__ReferenceID1">
<sap:WorkflowViewStateService.ViewState>
<scg3:Dictionary x:TypeArguments="x:String, x:Object">
<av:Point x:Key="ShapeLocation">194.5,299.5</av:Point>
<av:Size x:Key="ShapeSize">211,61</av:Size>
<av:PointCollection x:Key="ConnectorLocation">300,360.5 300,390.5 300,399</av:PointCollection>
</scg3:Dictionary>
</sap:WorkflowViewStateService.ViewState>
<WriteLine sap:VirtualizedContainerService.HintSize="211,61" Text="Workflow started" />
<FlowStep.Next>
<FlowStep x:Name="__ReferenceID3">
<sap:WorkflowViewStateService.ViewState>
<scg3:Dictionary x:TypeArguments="x:String, x:Object">
<av:Point x:Key="ShapeLocation">200,399</av:Point>
<av:Size x:Key="ShapeSize">200,22</av:Size>
<av:PointCollection x:Key="ConnectorLocation">300,421 300,451 300,479.5</av:PointCollection>
</scg3:Dictionary>
</sap:WorkflowViewStateService.ViewState>
<local:CodeActivity1 sap:VirtualizedContainerService.HintSize="200,22" />
<FlowStep.Next>
<FlowStep x:Name="__ReferenceID2">
<sap:WorkflowViewStateService.ViewState>
<scg3:Dictionary x:TypeArguments="x:String, x:Object">
<av:Point x:Key="ShapeLocation">194.5,479.5</av:Point>
<av:Size x:Key="ShapeSize">211,61</av:Size>
</scg3:Dictionary>
</sap:WorkflowViewStateService.ViewState>
<WriteLine sap:VirtualizedContainerService.HintSize="211,61" Text="The code activity worked!" />
</FlowStep>
</FlowStep.Next>
</FlowStep>
</FlowStep.Next>
</FlowStep>
</FlowStep.Next>
</FlowStep>
</Flowchart.StartNode>
<x:Reference>__ReferenceID0</x:Reference>
<x:Reference>__ReferenceID1</x:Reference>
<x:Reference>__ReferenceID2</x:Reference>
<x:Reference>__ReferenceID3</x:Reference>
</Flowchart>
</Activity>
DeclarativeServiceLibrary1.CodeActivity1.cs ...
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Activities;
namespace DeclarativeServiceLibrary1
{
public sealed class CodeActivity1 : CodeActivity
{
// Define an activity input argument of type string
//public InArgument<string> Text { get; set; }
// If your activity returns a value, derive from CodeActivity<TResult>
// and return the value from the Execute method.
protected override void Execute(CodeActivityContext context)
{
// Obtain the runtime value of the Text input argument
//string text = context.GetValue(this.Text);
}
}
}
DeclarativeServiceLibrary1.Web.Config ...
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.0" />
</system.web>
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior>
<!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
<serviceMetadata httpGetEnabled="true"/>
<!-- To receive exception details in faults for debugging purposes, set the value below to true. Set to false before deployment to avoid disclosing exception information -->
<serviceDebug includeExceptionDetailInFaults="false"/>
</behavior>
</serviceBehaviors>
</behaviors>
<serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
</system.serviceModel>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true"/>
</system.webServer>
</configuration>
ConsoleApplication1.Program.cs ...
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Activities;
using System.Activities.XamlIntegration;
using System.ServiceModel;
using System.ServiceModel.Activities;
using System.ServiceModel.Description;
using System.Xaml;
using System.Reflection;
using System.IO;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string baseAddress = @"http://localhost:8081/MyContractName";
string curDir = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
string wfDefPath = Path.Combine(curDir, "Activity1.xaml");
Activity workflowActivity = (Activity)ActivityXamlServices.Load(wfDefPath);
WorkflowService service = new WorkflowService { Body = workflowActivity };
Uri serviceUri = new Uri(baseAddress, UriKind.Absolute);
WorkflowServiceHost host = new WorkflowServiceHost(service, new Uri[] { serviceUri });
host.Open();
//Display that we are listening on the console window
Console.WriteLine("Workflow '{0}' is listening at '{1}'", host.Activity.DisplayName, baseAddress);
Console.ReadLine();
}
}
}
I have a post-build event in the delarative workflow service library that copies the Assembly and Xaml file into the bin\debug\ folder of the host console app.
Short answer - Xaml load can't infer the local (default) assembly, so you need to specify it on XamlReaderSettings.LocalAssembly.
Open source code of the activity. Change "xmlns:local="clr-namespace:DeclarativeServiceLibrary1" to xmlns:local="clr-namespace:DeclarativeServiceLibrary1;assembly=DeclarativeServiceLibrary1".
You're deserializing the xaml file directly, but it is referencing a type (CodeActivity1) that is compiled as a CLR type into the DeclarativeServiceLibrary1 assembly. The most obvious answer is that the DeclarativeServiceLibrary1 assembly is not available to the console app at runtime. Make sure that this assembly is copied into the folder where you are running the console app (\bin\debug) and see if that makes a difference.
The bottom line is that even though you are reading the xaml file directly, it still needs access to any types that it references.
By looking at your code I can tell that you should have loaded a WorkflowService instead of a simple activity. There are basically two options to try here:
Option 1: Load the activity and host it inside a generated workflow service.
You can do this by loading the activity as normal and use the following snippet to make it into a workflow service instance:
WorkflowService service = new WorkflowService();
service.Body = loadedActivity;
After that you can host it inside the workflow service host.
Option 2: Load the workflow service directly
The second option is not much different from what you have now. But instead of using the ActivityXamlServices class you will need to use the XamlServices class to load the workflow service. After that it's a matter of firing up the workflow service host with the settings you used in your sample.
来源：https://stackoverflow.com/questions/2330762/wf4-rc-cannot-create-unknown-type-when-loading-wf-service-from-loose-xaml-with