TFS 2010: Why is it not possible to deserialize a Dictionary<string, object> with XamlWriter.Save when I can use XamlReader for deserializing

Question

public static string GetXml(Dictionary<string, object> parameters)
{
    return XamlWriter.Save(parameters);
}

The above statement returns a NotSupportedException.

The strange thing is that I can use the XamlReader to serialize a dictionary.

public static Dictionary<string, object> GetParameters(IBuildDetail buildDetail, string buildDefinition)
{
    var tfsProject = buildDetail.BuildDefinition.TeamProject;
    var buildServer = buildDetail.BuildServer;
    var buildDef = buildServer.GetBuildDefinition(tfsProject, buildDefinition);
    using (var stringReader = new StringReader(buildDef.ProcessParameters))
    {
        using (var xmlTextReader = new XmlTextReader(stringReader))
        {
            return (Dictionary<string, object>) XamlReader.Load(xmlTextReader);
        }
    }
}

The XML:

<?xml version="1.0" ?>
<Dictionary x:TypeArguments="x:String, x:Object" xmlns="clr-namespace:System.Collections.Generic;assembly=mscorlib" xmlns:mtbwa="clr-namespace:Microsoft.TeamFoundation.Build.Workflow.Activities;assembly=Microsoft.TeamFoundation.Build.Workflow" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

  <mtbwa:BuildSettings ProjectsToBuild="$/XXX/Product/Company.XXX.Common/Company.XXX.Common.Basic/Company.XXX.Common.Basic.csproj" x:Key="BuildSettings">

    <mtbwa:BuildSettings.PlatformConfigurations>

      <mtbwa:PlatformConfigurationList Capacity="4">

        <mtbwa:PlatformConfiguration Configuration="DEMO" Platform="AnyCPU"/>

        <mtbwa:PlatformConfiguration Configuration="Release" Platform="AnyCPU"/>

      </mtbwa:PlatformConfigurationList>

    </mtbwa:BuildSettings.PlatformConfigurations>

  </mtbwa:BuildSettings>

  <mtbwa:TestSpecList Capacity="0" x:Key="TestSpecs"/>

  <x:String x:Key="BuildNumberFormat">
    $(BuildDefinitionName) 6.0.0$(Rev:.r)
  </x:String>

  <mtbwa:CodeAnalysisOption x:Key="RunCodeAnalysis">
    Never
  </mtbwa:CodeAnalysisOption>

  <mtbwa:AgentSettings MaxWaitTime="00:15:00" TagComparison="MatchExactly" Tags="" x:Key="AgentSettings"/>

  <x:Boolean x:Key="AssociateChangesetsAndWorkItems">
    False
  </x:Boolean>

  <x:Boolean x:Key="CreateWorkItem">
    False
  </x:Boolean>

  <x:Boolean x:Key="PerformTestImpactAnalysis">
    False
  </x:Boolean>

  <x:Boolean x:Key="CreateLabel">
    False
  </x:Boolean>

  <x:Boolean x:Key="DisableTests">
    True
  </x:Boolean>

  <x:Boolean x:Key="DoCheckinAssemblyInfoFiles">
    True
  </x:Boolean>

  <x:String x:Key="AssemblyVersionPattern">
    6.0.0.0
  </x:String>

  <x:String x:Key="AssemblyFileVersionPattern">
    6.0.0.B
  </x:String>

  <x:Boolean x:Key="UseObfuscation">
    True
  </x:Boolean>

  <x:String x:Key="ObfuscatorFilePath">
    C:\Program Files (x86)\LogicNP Software\Crypto Obfuscator For .Net 2011 R3\co.exe
  </x:String>

  <x:String x:Key="ObfuscatorProjectFile">
    $/XXX/Product/BuildProcess/Company.XXX.ZZZ.obproj
  </x:String>

  <x:String x:Key="ProjectPath">
    $/XXX/Product/Company.XXX.Common
  </x:String>

</Dictionary>

Answer 1

I used JetBrains dotPeek to find out how Microsoft is serializing and deserializing a Dictionary<string, object> for TFS 2010 Workflow.

For Deserializing they use: Microsoft.TeamFoundation.Build.Workflow.WorkflowHelpers.DeserializeProcessParameters(string parameterValues)

For Serializing they use: WorkflowHelpers.SerializeProcessParameters(IDictionary<string, object> parameterValues)

Assembly: Microsoft.TeamFoundation.Build.Workflow.dll

My original problem was that I tried to add IBuildRequest.ProcessParameters values before queueing a build.

private static void SetProcessParametersForSubBuild(IBuildRequest buildRequest, Dictionary<string, object> processParametersForSubBuild, IBuildDefinition buildDefinition)
{
    var subBuildProcessParameters = WorkflowHelpers.DeserializeProcessParameters(buildDefinition.ProcessParameters);

    if (processParametersForSubBuild.Any())
    {
        foreach (var processParameter in processParametersForSubBuild)
        {
            if (subBuildProcessParameters.ContainsKey(processParameter.Key))
            {
                subBuildProcessParameters[processParameter.Key] = processParameter.Value;
            }
            else
            {
                subBuildProcessParameters.Add(processParameter.Key, processParameter.Value);
            }
        }
        buildRequest.ProcessParameters = WorkflowHelpers.SerializeProcessParameters(subBuildProcessParameters);
    }
}

Queue Build:

var queuedBuild = buildServer.QueueBuild(buildRequest);

Answer 2

is it a must to use XamlReader/XamlWriter? If not - take a look at DataContractSerializer:

public static class SerializationExtensions
{
    public static string Serialize<T>(this T obj)
    {
        var serializer = new DataContractSerializer(obj.GetType());
        using (var writer = new StringWriter())
        using (var stm = new XmlTextWriter(writer))
        {
            serializer.WriteObject(stm, obj);
            return writer.ToString();
        }
    }
    public static T Deserialize<T>(this string serialized)
    {
        var serializer = new DataContractSerializer(typeof(T));
        using (var reader = new StringReader(serialized))
        using (var stm = new XmlTextReader(reader))
        {
            return (T)serializer.ReadObject(stm);
        }
    }
}

(credits to https://stackoverflow.com/a/5941122/1246870)