SoapExtension Class

The base class for SOAP extensions for XML Web services created using ASP.NET.

System::Object
  System.Web.Services.Protocols::SoapExtension

Namespace:  System.Web.Services.Protocols
Assembly:  System.Web.Services (in System.Web.Services.dll)

public ref class SoapExtension abstract

The SoapExtension type exposes the following members.

  NameDescription
Protected methodSoapExtensionInitializes a new instance of the SoapExtension class.
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  NameDescription
Public methodChainStreamWhen overridden in a derived class, allows a SOAP extension access to the memory buffer containing the SOAP request or response.
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetInitializer(Type)When overridden in a derived class, allows a SOAP extension to initialize data specific to a class implementing an XML Web service at a one time performance cost.
Public methodGetInitializer(LogicalMethodInfo, SoapExtensionAttribute)When overridden in a derived class, allows a SOAP extension to initialize data specific to an XML Web service method using an attribute applied to the XML Web service method at a one time performance cost.
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodInitializeWhen overridden in a derived class, allows a SOAP extension to initialize itself using the data cached in the GetInitializer method.
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodProcessMessageWhen overridden in a derived class, allows a SOAP extension to receive a SoapMessage to process at each SoapMessageStage.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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ASP.NET allows a SOAP-related infrastructure to be built by means of an extensibility mechanism. The ASP.NET SOAP extension architecture revolves around an extension that can inspect or modify a message at specific stages in message processing on either the client or the server.

ASP.NET SOAP extensions derive from the SoapExtension class. The GetInitializer and Initialize methods provide alternative mechanisms for initializing the SOAP extension to enhance performance. ProcessMessage is the heart of most SOAP extensions, as the method is called at each stage defined in SoapMessageStage, allowing the SOAP extension to perform the desired behavior of that specific SOAP extension. For SOAP extensions that need to modify the SOAP request or SOAP response, ChainStream provides an opportunity to receive the proposed data to be sent across the wire.

The following TraceExtension SOAP extension outputs the SOAP request and SOAP response to a specified file when applied to an XML Web service method. If the following SOAP extension is installed to run with an XML Web service, the ASPNET user account must have permission to write to the directory in which the log file is written.

#using <System.dll>
#using <System.Web.Services.dll>

using namespace System;
using namespace System::Web::Services;
using namespace System::Web::Services::Protocols;
using namespace System::IO;
using namespace System::Net;

ref class TraceExtension;

// Create a SoapExtensionAttribute for the SOAP Extension that can be 
// applied to an XML Web service method.
[AttributeUsage(AttributeTargets::Method)]
public ref class TraceExtensionAttribute: public SoapExtensionAttribute
{
private:
   String^ filename;
   int priority;

public:
   TraceExtensionAttribute()
      : filename( "c:\\log.txt" )
   {}

   property Type^ ExtensionType 
   {
      virtual Type^ get() override
      {
         return TraceExtension::typeid;
      }
   }

   property int Priority 
   {
      virtual int get() override
      {
         return priority;
      }
      virtual void set( int value ) override
      {
         priority = value;
      }
   }

   property String^ Filename 
   {
      String^ get()
      {
         return filename;
      }
      void set( String^ value )
      {
         filename = value;
      }
   }
};

// Define a SOAP Extension that traces the SOAP request and SOAP 
// response for the XML Web service method the SOAP extension is 
// applied to. 
public ref class TraceExtension: public SoapExtension
{
private:
   Stream^ oldStream;
   Stream^ newStream;
   String^ filename;

public:
   // Save the Stream representing the SOAP request or SOAP response into 
   // a local memory buffer. 
   virtual Stream^ ChainStream( Stream^ stream ) override
   {
      oldStream = stream;
      newStream = gcnew MemoryStream;
      return newStream;
   }

   // When the SOAP extension is accessed for the first time, the XML Web 
   // service method it is applied to is accessed to store the file 
   // name passed in, using the corresponding SoapExtensionAttribute.  
   virtual Object^ GetInitializer( LogicalMethodInfo^ /*methodInfo*/, SoapExtensionAttribute^ attribute ) override
   {
      return (dynamic_cast<TraceExtensionAttribute^>(attribute))->Filename;
   }

   // The SOAP extension was configured to run using a configuration file 
   // instead of an attribute applied to a specific XML Web service 
   // method. 
   virtual Object^ GetInitializer( Type^ WebServiceType ) override
   {
      // Return a file name to log the trace information to, based on the 
      // type. 
      return String::Format( "C:\\{0}.log", WebServiceType->FullName );
   }

   // Receive the file name stored by GetInitializer and store it in a 
   // member variable for this specific instance. 
   virtual void Initialize( Object^ initializer ) override
   {
      filename = dynamic_cast<String^>(initializer);
   }

   //  If the SoapMessageStage is such that the SoapRequest or 
   //  SoapResponse is still in the SOAP format to be sent or received, 
   //  save it out to a file. 
   virtual void ProcessMessage( SoapMessage^ message ) override
   {
      switch ( message->Stage )
      {
         case SoapMessageStage::BeforeSerialize:
            break;
         case SoapMessageStage::AfterSerialize:
            WriteOutput( message );
            break;
         case SoapMessageStage::BeforeDeserialize:
            WriteInput( message );
            break;
         case SoapMessageStage::AfterDeserialize:
            break;
      }
   }

   void WriteOutput( SoapMessage^ message )
   {
      newStream->Position = 0;
      FileStream^ fs = gcnew FileStream( filename, FileMode::Append,
         FileAccess::Write );
      StreamWriter^ w = gcnew StreamWriter( fs );

      String^ soapString = ( (SoapServerMessage^)( message ) ) ?
         (String^)"SoapResponse" : "SoapRequest";
      w->WriteLine( "-----{0} at {1}", soapString, DateTime::Now );
      w->Flush();
      Copy( newStream, fs );
      w->Close();
      newStream->Position = 0;
      Copy( newStream, oldStream );
   }

   void WriteInput( SoapMessage^ message )
   {
      Copy( oldStream, newStream );
      FileStream^ fs = gcnew FileStream( filename,FileMode::Append,FileAccess::Write );
      StreamWriter^ w = gcnew StreamWriter( fs );
      String^ soapString = (dynamic_cast<SoapServerMessage^>(message)) ? (String^)"SoapRequest" : "SoapResponse";
      w->WriteLine( "-----{0} at {1}", soapString, DateTime::Now );
      w->Flush();
      newStream->Position = 0;
      Copy( newStream, fs );
      w->Close();
      newStream->Position = 0;
   }

   void Copy( Stream^ from, Stream^ to )
   {
      TextReader^ reader = gcnew StreamReader( from );
      TextWriter^ writer = gcnew StreamWriter( to );
      writer->WriteLine( reader->ReadToEnd() );
      writer->Flush();
   }
};

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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