This topic has not yet been rated - Rate this topic

MessageEncoder Class

The encoder is the component that is used to write messages to a stream and to read messages from a stream.

System.Object
  System.ServiceModel.Channels.MessageEncoder

Namespace:  System.ServiceModel.Channels
Assembly:  System.ServiceModel (in System.ServiceModel.dll)
public abstract class MessageEncoder

The MessageEncoder type exposes the following members.

  NameDescription
Protected methodSupported by Portable Class LibraryMessageEncoderInitializes a new instance of the MessageEncoder class.
Top
  NameDescription
Public propertySupported by Portable Class LibraryContentTypeWhen overridden in a derived class, gets the MIME content type used by the encoder.
Public propertySupported by Portable Class LibraryMediaTypeWhen overridden in a derived class, gets the media type value that is used by the encoder.
Public propertySupported by Portable Class LibraryMessageVersionWhen overridden in a derived class, gets the message version value that is used by the encoder.
Top
  NameDescription
Public methodSupported by Portable Class LibraryEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by Portable Class LibraryFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by Portable Class LibraryGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by Portable Class LibraryGetProperty<T>Returns a typed object requested, if present, from the appropriate layer in the channel stack.
Public methodSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodSupported by Portable Class LibraryIsContentTypeSupportedReturns a value that indicates whether a specified message-level content-type value is supported by the message encoder.
Protected methodSupported by Portable Class LibraryMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by Portable Class LibraryReadMessage(ArraySegment<Byte>, BufferManager)When overridden in a derived class, reads a message from a specified buffer.
Public methodSupported by Portable Class LibraryReadMessage(Stream, Int32)When overridden in a derived class, reads a message from a specified stream.
Public methodSupported by Portable Class LibraryReadMessage(ArraySegment<Byte>, BufferManager, String)When overridden in a derived class, reads a message from a specified stream.
Public methodSupported by Portable Class LibraryReadMessage(Stream, Int32, String)When overridden in a derived class, reads a message from a specified stream.
Public methodSupported by Portable Class LibraryToStringReturns the content type that is used by the message encoder. (Overrides Object.ToString().)
Public methodSupported by Portable Class LibraryWriteMessage(Message, Stream)When overridden in a derived class, writes a message to a specified stream.
Public methodSupported by Portable Class LibraryWriteMessage(Message, Int32, BufferManager)Writes a message less than a specified size to a byte array buffer.
Public methodSupported by Portable Class LibraryWriteMessage(Message, Int32, BufferManager, Int32)When overridden in a derived class, writes a message of less than a specified size to a byte array buffer at the specified offset.
Top

MessageEncoder is a base class that provides implementations that support a Multipurpose Internet Mail Extensions (MIME) content type and message version, and defines the interface for the serialization and deserialization of messages according to that content type. Use it as a base class for writing your own custom encoder.

Use this class if you want to implement a custom message encoder. To implement your own custom message encoder, you must provide custom implementations of the following abstract base classes:

Override the Encoder to return an instance of your custom MessageEncoder. Then wire up your custom MessageEncoderFactory to the binding element stack used to configure the service or client by overriding the CreateMessageEncoderFactory method to return an instance of this factory.

The task of converting between the in-memory representation of a message and an XML Information Set (Infoset) representation that can be written to a stream is encapsulated within the MessageEncoder class, which most commonly serves as a factory for XML readers and XML writers that support specific types of XML encodings.

The key methods on MessageEncoder are WriteMessage() and ReadMessage(). WriteMessage() takes a Message object and writes it into a Stream object. ReadMessage() takes a Stream object and a maximum header size and returns a Message object.

The following code shows an example of a class that is derived from MessageEncoder.


public class CustomTextMessageEncoder : MessageEncoder
{
    private CustomTextMessageEncoderFactory factory;
    private XmlWriterSettings writerSettings;
    private string contentType;

    public CustomTextMessageEncoder(CustomTextMessageEncoderFactory factory)
    {
        this.factory = factory;

        this.writerSettings = new XmlWriterSettings();
        this.writerSettings.Encoding = Encoding.GetEncoding(factory.CharSet);
        this.contentType = string.Format("{0}; charset={1}", 
            this.factory.MediaType, this.writerSettings.Encoding.HeaderName);
    }

    public override string ContentType
    {
        get
        {
            return this.contentType;
        }
    }

    public override string MediaType
    {
        get 
        {
            return factory.MediaType;
        }
    }

    public override MessageVersion MessageVersion
    {
        get 
        {
            return this.factory.MessageVersion;
        }
    }

    public override bool IsContentTypeSupported(string contentType) 
    { 
        if (base.IsContentTypeSupported(contentType)) 
        { 
            return true; 
        } 
        if (contentType.Length == this.MediaType.Length) 
        { 
            return contentType.Equals(this.MediaType, StringComparison.OrdinalIgnoreCase); 
        } 
        else 
        { 
            if (contentType.StartsWith(this.MediaType, StringComparison.OrdinalIgnoreCase) 
                && (contentType[this.MediaType.Length] == ';')) 
            { 
                return true; 
            } 
        } 
        return false; 
    }

    public override Message ReadMessage(ArraySegment<byte> buffer, BufferManager bufferManager, string contentType)
    {   
        byte[] msgContents = new byte[buffer.Count];
        Array.Copy(buffer.Array, buffer.Offset, msgContents, 0, msgContents.Length);
        bufferManager.ReturnBuffer(buffer.Array);

        MemoryStream stream = new MemoryStream(msgContents);
        return ReadMessage(stream, int.MaxValue);
    }

    public override Message ReadMessage(Stream stream, int maxSizeOfHeaders, string contentType)
    {
        XmlReader reader = XmlReader.Create(stream);
        return Message.CreateMessage(reader, maxSizeOfHeaders, this.MessageVersion);
    }

    public override ArraySegment<byte> WriteMessage(Message message, int maxMessageSize, BufferManager bufferManager, int messageOffset)
    {
        MemoryStream stream = new MemoryStream();
        XmlWriter writer = XmlWriter.Create(stream, this.writerSettings);
        message.WriteMessage(writer);
        writer.Close();

        byte[] messageBytes = stream.GetBuffer();
        int messageLength = (int)stream.Position;
        stream.Close();

        int totalLength = messageLength + messageOffset;
        byte[] totalBytes = bufferManager.TakeBuffer(totalLength);
        Array.Copy(messageBytes, 0, totalBytes, messageOffset, messageLength);

        ArraySegment<byte> byteArray = new ArraySegment<byte>(totalBytes, messageOffset, messageLength);
        return byteArray;
    }

    public override void WriteMessage(Message message, Stream stream)
    {
        XmlWriter writer = XmlWriter.Create(stream, this.writerSettings);
        message.WriteMessage(writer);
        writer.Close();
    }


.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Did you find this helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

ADD
Show:
© 2014 Microsoft. All rights reserved.