如何：自定义服务说明和代理类的生成

项目
12/31/2007

下面的代码示例是一个 SDFE，它扩展了服务说明和代理生成过程，从而包括有关 YML SOAP 扩展的详细信息。

示例

Imports System
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.IO
Imports System.Text
Imports System.Web.Services.Configuration
Imports System.Web.Services.Description
Imports System.Xml.Serialization
Imports System.CodeDom

' The YMLAttribute allows a developer to specify that the YML SOAP
' extension run on a per-method basis.  The disabled property
' turns reversing the XML on and off. 
<AttributeUsage(AttributeTargets.Method, AllowMultiple:=False)> _
Public Class YMLAttribute
    Inherits SoapExtensionAttribute
    Dim _priority As Integer = 0
    Dim _disabled As Boolean = False

    Public Sub New()
        Me.New(False)
    End Sub
    Public Sub New(ByVal Disabled As Boolean)
        _disabled = Disabled
    End Sub
    Public Overrides ReadOnly Property ExtensionType() As Type
        Get
            Return GetType(YMLExtension)
        End Get
    End Property
    Public Overrides Property Priority() As Integer
        Get
            Return _priority
        End Get
        Set(ByVal Value As Integer)
            _priority = Value
        End Set
    End Property

    Public Property Disabled() As Boolean
        Get
            Return _disabled
        End Get
        Set(ByVal Value As Boolean)
            _disabled = Value
        End Set
    End Property
End Class

Public Class YMLExtension
    Inherits SoapExtension
    Dim _disabled As Boolean = False
    Dim oldStream As Stream
    Dim newStream As Stream

    Public Overloads Overrides Function GetInitializer(ByVal methodInfo _
                   As LogicalMethodInfo, _
                   ByVal attribute As SoapExtensionAttribute) As Object
        Dim attr As YMLAttribute = attribute
        If (Not attr Is Nothing) Then
            Return attr.Disabled
        End If
        Return False
    End Function

    Public Overloads Overrides Function GetInitializer(ByVal _
      WebServiceType As Type) As Object
        Return False
    End Function

    Public Overrides Sub Initialize(ByVal initializer As Object)
        If (TypeOf initializer Is Boolean) Then
            _disabled = CBool(initializer)
        End If
    End Sub

    Public Overrides Function ChainStream(ByVal streamref As Stream) _
      As Stream
        If (_disabled) Then
            Return CType(Me, SoapExtension).ChainStream(streamref)
        End If
        oldStream = streamref
        newStream = New MemoryStream()
        Return newStream
    End Function

    Public Overrides Sub ProcessMessage(ByVal message As SoapMessage)
        If (_disabled) Then Return
        Select Case (message.Stage)
            Case SoapMessageStage.BeforeSerialize
                Encode(message)
            Case SoapMessageStage.AfterSerialize
                newStream.Position = 0
                Reverse(newStream, oldStream)
            Case SoapMessageStage.BeforeDeserialize
                Decode(message)
            Case SoapMessageStage.AfterDeserialize
        End Select
    End Sub

    Sub Encode(ByRef message As SoapMessage)
        message.ContentType = "text/yml"
    End Sub

    Sub Decode(ByVal message As SoapMessage)
        If (message.ContentType <> "text/yml") Then
            Throw New Exception("invalid content type:" + _
                                 message.ContentType)
        End If
        Reverse(oldStream, newStream)
        newStream.Position = 0
        message.ContentType = "text/xml"
    End Sub

    Sub Reverse(ByVal source As Stream, ByVal dest As Stream)
        Dim reader As TextReader = New StreamReader(source)
        Dim writer As TextWriter = New StreamWriter(dest)
        Dim line As String
        line = reader.ReadLine()
        While (Not line Is Nothing)
            writer.WriteLine(StrReverse(line))
            line = reader.ReadLine()
        End While
        writer.Flush()
    End Sub
End Class

' The YMLReflector class is part of the YML SDFE; it is
' called during the service description generation process.
Public Class YMLReflector
    Inherits SoapExtensionReflector
    Public Overrides Sub ReflectMethod()
        Dim reflector As ProtocolReflector = ReflectionContext
        Dim attr As YMLAttribute = _
            reflector.Method.GetCustomAttribute(GetType(YMLAttribute))
        ' If the YMLAttribute has been applied to this Web service 
        ' method, adds the XML defined in the YMLOperationBinding class.
        If (Not attr Is Nothing) Then
            Dim yml As YMLOperationBinding = New YMLOperationBinding()
            yml.Reverse = Not attr.Disabled
            reflector.OperationBinding.Extensions.Add(yml)
        End If
    End Sub
End Class

' The YMLImporter class is part of the YML SDFE; it is called when
' a proxy class is generated for each Web service method the proxy
' class communicates with.  The class checks whether the service
' description contains the XML that this SDFE adds to a service
' description.  If it exists, then the YMLExtension is applied to the
' method in the proxy class.
Public Class YMLImporter
    Inherits SoapExtensionImporter
    Public Overrides Sub ImportMethod(ByVal metadata As _
                           CodeAttributeDeclarationCollection)
      Dim importer As SoapProtocolImporter = ImportContext
      ' Checks whether the XML specified in the YMLOperationBinding is 
      ' in the service description.
      Dim yml As YMLOperationBinding = _
        importer.OperationBinding.Extensions.Find(
        GetType(YMLOperationBinding))
      If (Not yml Is Nothing) Then
         ' Only applies the YMLAttribute to the method when the XML
         ' should be reversed.
         If (yml.Reverse) Then
            Dim attr As CodeAttributeDeclaration = New _
               CodeAttributeDeclaration(GetType(YMLAttribute).FullName)
            attr.Arguments.Add(New CodeAttributeArgument(New _
               CodePrimitiveExpression(True)))
            metadata.Add(attr)
         End If
       End If
    End Sub
End Class

' The YMLOperationBinding class is part of the YML SDFE; it is the
' class that is serialized into XML and placed in the service
' description.
<XmlFormatExtension("action", YMLOperationBinding.YMLNamespace, _
                     GetType(OperationBinding)), _
 XmlFormatExtensionPrefix("yml", YMLOperationBinding.YMLNamespace)> _
Public Class YMLOperationBinding
    Inherits ServiceDescriptionFormatExtension
    Private _reverse As Boolean
    Public Const YMLNamespace As String = "https://www.contoso.com/yml"

    <XmlElement("Reverse")> _
    Public Property Reverse() As Boolean
        Get
            Return _reverse
        End Get
        Set(ByVal Value As Boolean)
            _reverse = Value
        End Set
    End Property
End Class

using System;
using System.CodeDom;
using System.IO;
using System.Text;
using System.Web.Services.Configuration;
using System.Web.Services.Description;
using System.Web.Services.Protocols;
using System.Xml.Serialization;
 
// The YMLAttribute allows a developer to specify that the YML SOAP
// extension run on a per-method basis.  The disabled property
// turns reversing the XML on and off. 

[AttributeUsage(AttributeTargets.Method, AllowMultiple=false)]
public class YMLAttribute : SoapExtensionAttribute 
{
  int priority = 0;
  bool disabled = false;
       
  public YMLAttribute() : this(false) {}
  public YMLAttribute(bool disabled) 
  {
     this.disabled = disabled;
  }
      
  public override Type ExtensionType 
  {
    get { return typeof(YMLExtension); }
  }
  public override int Priority 
  {
    get { return priority; }
    set { priority = value; }
  }

  public bool Disabled 
  { 
    get { return disabled; }
    set { disabled = value; }
  }
}

public class YMLExtension : SoapExtension 
{
  bool disabled = false;
  Stream oldStream;
  Stream newStream;

  public override object GetInitializer(LogicalMethodInfo methodInfo,
                                        SoapExtensionAttribute attribute)
  {
    YMLAttribute attr = attribute as YMLAttribute;
    if (attr != null) return attr.Disabled;
       return false;
  }

  public override object GetInitializer(Type serviceType) 
  {
        return false;
  }

  public override void Initialize(object initializer) 
  {
     if (initializer is Boolean) disabled = (bool)initializer;
  }

  public override Stream ChainStream(Stream stream) 
  {
     if (disabled) return base.ChainStream(stream);
     oldStream = stream;
     newStream = new MemoryStream();
     return newStream;
  }

  public override void ProcessMessage(SoapMessage message) 
  {
    if (disabled) return;
    switch (message.Stage) 
    {
      case SoapMessageStage.BeforeSerialize:
        Encode(message);
        break;
      case SoapMessageStage.AfterSerialize:
        newStream.Position = 0;
        Reverse(newStream, oldStream);
        break;
      case SoapMessageStage.BeforeDeserialize:
        Decode(message);
        break;
      case SoapMessageStage.AfterDeserialize:
        break;
    }
  }        
  void Encode(SoapMessage message) 
  {
     message.ContentType = "text/yml";
  }

  void Decode(SoapMessage message) 
  {
   if (message.ContentType != "text/yml") 
     throw new Exception("invalid content type:" + message.ContentType);
   Reverse(oldStream, newStream);
   newStream.Position = 0;
   message.ContentType = "text/xml";
  }

  void Reverse(Stream from, Stream to) 
  {
    TextReader reader = new StreamReader(from);
    TextWriter writer = new StreamWriter(to);
    string line;
    while ((line = reader.ReadLine()) != null) 
    {
      StringBuilder builder = new StringBuilder();
      for (int i = line.Length - 1; i >= 0; i--) 
      {
        builder.Append(line[i]);
      }
      writer.WriteLine(builder.ToString());
    }
    writer.Flush();
  }
}

// The YMLReflector class is part of the YML SDFE; it is
// called during the service description generation process.
public class YMLReflector : SoapExtensionReflector 
{
  public override void ReflectMethod() 
  {
    ProtocolReflector reflector = ReflectionContext;
    YMLAttribute attr = (YMLAttribute)reflector.Method.GetCustomAttribute(
                        typeof(YMLAttribute));
    // If the YMLAttribute has been applied to this Web service
    // method, adds the XML defined in the YMLOperationBinding class.
    if (attr != null) 
    {
      YMLOperationBinding yml = new YMLOperationBinding();
      yml.Reverse = !(attr.Disabled);
      reflector.OperationBinding.Extensions.Add(yml);
    }
  }
}
  
// The YMLImporter class is part of the YML SDFE; it is called when
// a proxy class is generated for each Web service method the proxy
// class communicates with.  The class checks whether the service
// description contains the XML that this SDFE adds to a service
// description.  If it exists, then the YMLExtension is applied to the
// method in the proxy class.
public class YMLImporter : SoapExtensionImporter 
{
  public override void ImportMethod(CodeAttributeDeclarationCollection
                                    metadata)
 {
    SoapProtocolImporter importer = ImportContext;
   // Checks whether the XML specified in the YMLOperationBinding is in
   // the service description.
   YMLOperationBinding yml = (YMLOperationBinding)
       importer.OperationBinding.Extensions.Find(
       typeof(YMLOperationBinding));
   if (yml != null)
   {
     // Only applies the YMLAttribute to the method when the XML should
     // be reversed.
     if (yml.Reverse)
     {
       CodeAttributeDeclaration attr = new CodeAttributeDeclaration(
            typeof(YMLAttribute).FullName);
       attr.Arguments.Add(new CodeAttributeArgument(new
         CodePrimitiveExpression(true)));
       metadata.Add(attr);
     }
   }
 }
}

// The YMLOperationBinding class is part of the YML SDFE; it is the
// class that is serialized into XML and placed in the service
// description.
[XmlFormatExtension("action", YMLOperationBinding.YMLNamespace,
                    typeof(OperationBinding))]
[XmlFormatExtensionPrefix("yml", YMLOperationBinding.YMLNamespace)]
public class YMLOperationBinding : ServiceDescriptionFormatExtension 
{
   private Boolean reverse;
   public const string YMLNamespace = "https://www.contoso.com/yml";

   [XmlElement("Reverse")]
   public Boolean Reverse 
   {
     get { return reverse; }
     set { reverse = value; }
   }
}

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如何：自定义服务说明和代理类的生成

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